{- Data/Singletons/TH/Single.hs

(c) Richard Eisenberg 2013
rae@cs.brynmawr.edu

This file contains functions to refine constructs to work with singleton
types. It is an internal module to the singletons-th package.
-}
{-# LANGUAGE TemplateHaskellQuotes, TupleSections, ParallelListComp #-}

module Data.Singletons.TH.Single where

import Prelude hiding ( exp )
import Language.Haskell.TH hiding ( cxt )
import Language.Haskell.TH.Syntax (NameSpace(..), Quasi(..))
import Data.Singletons.TH.Deriving.Bounded
import Data.Singletons.TH.Deriving.Enum
import Data.Singletons.TH.Deriving.Eq
import Data.Singletons.TH.Deriving.Infer
import Data.Singletons.TH.Deriving.Ord
import Data.Singletons.TH.Deriving.Show
import Data.Singletons.TH.Deriving.Util
import Data.Singletons.TH.Names
import Data.Singletons.TH.Options
import Data.Singletons.TH.Partition
import Data.Singletons.TH.Promote
import Data.Singletons.TH.Promote.Defun
import Data.Singletons.TH.Promote.Monad ( promoteM )
import Data.Singletons.TH.Promote.Type
import Data.Singletons.TH.Single.Data
import Data.Singletons.TH.Single.Decide
import Data.Singletons.TH.Single.Defun
import Data.Singletons.TH.Single.Fixity
import Data.Singletons.TH.Single.Monad
import Data.Singletons.TH.Single.Type
import Data.Singletons.TH.Syntax
import Data.Singletons.TH.Util
import Language.Haskell.TH.Desugar
import qualified Language.Haskell.TH.Desugar.OMap.Strict as OMap
import Language.Haskell.TH.Desugar.OMap.Strict (OMap)
import qualified Language.Haskell.TH.Desugar.OSet as OSet
import Language.Haskell.TH.Desugar.OSet (OSet)
import qualified Data.Map.Strict as Map
import Data.Map.Strict ( Map )
import Data.Maybe
import qualified Data.Set as Set
import Control.Monad
import Control.Monad.Trans.Class
import Data.List (unzip6, zipWith4)
import qualified GHC.LanguageExtensions.Type as LangExt

{-
How singletons-th works
~~~~~~~~~~~~~~~~~~~~~~~

Singling, on the surface, doesn't seem all that complicated. Promote the type,
and singletonize all the terms. That's essentially what was done singletons < 1.0.
But, now we want to deal with higher-order singletons. So, things are a little
more complicated.

The way to understand all of this is that *every* variable maps to something
of type (Sing t), for an appropriately-kinded t. This includes functions, which
use the "SLambda" instance of Sing. To apply singleton functions, we use the
applySing function.

That, in and of itself, wouldn't be too hard, but it's really annoying from
the user standpoint. After dutifully singling `map`, a user doesn't want to
have to use two `applySing`s to actually use it. So, any let-bound identifier
is eta-expanded so that the singled type has the same number of arrows as
the original type. (If there is no original type signature, then it has as
many arrows as the original had patterns.) Then, we store a use of one of the
singFunX functions in the SgM environment so that every use of a let-bound
identifier has a proper type (Sing t).

It would be consistent to avoid this eta-expansion for local lets (as opposed
to top-level lets), but that seemed like more bother than it was worth. It
may also be possible to be cleverer about nested eta-expansions and contractions,
but that also seemed not to be worth it. Though I haven't tested it, my hope
is that the eta-expansions and contractions have no runtime effect, especially
because SLambda is a *newtype* instance, not a *data* instance.

Note that to maintain the desired invariant, we must also be careful to eta-
contract constructors. This is the point of buildDataLets.
-}

-- | Generate singled definitions for each of the provided type-level
-- declaration 'Name's. For example, the singletons-th package itself uses
--
-- > $(genSingletons [''Bool, ''Maybe, ''Either, ''[]])
--
-- to generate singletons for Prelude types.
genSingletons :: OptionsMonad q => [Name] -> q [Dec]
genSingletons :: forall (q :: * -> *). OptionsMonad q => [Name] -> q [Dec]
genSingletons [Name]
names = do
  Options
opts <- q Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  -- See Note [Disable genQuotedDecs in genPromotions and genSingletons]
  -- in D.S.TH.Promote
  Options -> OptionsM q [Dec] -> q [Dec]
forall (m :: * -> *) a. Options -> OptionsM m a -> m a
withOptions Options
opts{genQuotedDecs :: Bool
genQuotedDecs = Bool
False} (OptionsM q [Dec] -> q [Dec]) -> OptionsM q [Dec] -> q [Dec]
forall a b. (a -> b) -> a -> b
$ do
    [Name] -> OptionsM q ()
forall (q :: * -> *). Quasi q => [Name] -> q ()
checkForRep [Name]
names
    [DDec]
ddecs <- (Name -> OptionsM q [DDec]) -> [Name] -> OptionsM q [DDec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM (DInfo -> OptionsM q [DDec]
forall (q :: * -> *). OptionsMonad q => DInfo -> q [DDec]
singInfo (DInfo -> OptionsM q [DDec])
-> (Name -> OptionsM q DInfo) -> Name -> OptionsM q [DDec]
forall (m :: * -> *) b c a.
Monad m =>
(b -> m c) -> (a -> m b) -> a -> m c
<=< Info -> OptionsM q DInfo
forall (q :: * -> *). DsMonad q => Info -> q DInfo
dsInfo (Info -> OptionsM q DInfo)
-> (Name -> OptionsM q Info) -> Name -> OptionsM q DInfo
forall (m :: * -> *) b c a.
Monad m =>
(b -> m c) -> (a -> m b) -> a -> m c
<=< Name -> OptionsM q Info
forall (q :: * -> *). DsMonad q => Name -> q Info
reifyWithLocals) [Name]
names
    [Dec] -> OptionsM q [Dec]
forall (m :: * -> *) a. Monad m => a -> m a
return ([Dec] -> OptionsM q [Dec]) -> [Dec] -> OptionsM q [Dec]
forall a b. (a -> b) -> a -> b
$ [DDec] -> [Dec]
decsToTH [DDec]
ddecs

-- | Make promoted and singled versions of all declarations given, retaining
-- the original declarations. See the
-- @<https://github.com/goldfirere/singletons/blob/master/README.md README>@
-- for further explanation.
singletons :: OptionsMonad q => q [Dec] -> q [Dec]
singletons :: forall (q :: * -> *). OptionsMonad q => q [Dec] -> q [Dec]
singletons q [Dec]
qdecs = do
  Options
opts <- q Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  Options -> OptionsM q [Dec] -> q [Dec]
forall (m :: * -> *) a. Options -> OptionsM m a -> m a
withOptions Options
opts{genQuotedDecs :: Bool
genQuotedDecs = Bool
True} (OptionsM q [Dec] -> q [Dec]) -> OptionsM q [Dec] -> q [Dec]
forall a b. (a -> b) -> a -> b
$ OptionsM q [Dec] -> OptionsM q [Dec]
forall (q :: * -> *). OptionsMonad q => q [Dec] -> q [Dec]
singletons' (OptionsM q [Dec] -> OptionsM q [Dec])
-> OptionsM q [Dec] -> OptionsM q [Dec]
forall a b. (a -> b) -> a -> b
$ q [Dec] -> OptionsM q [Dec]
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift q [Dec]
qdecs

-- | Make promoted and singled versions of all declarations given, discarding
-- the original declarations. Note that a singleton based on a datatype needs
-- the original datatype, so this will fail if it sees any datatype declarations.
-- Classes, instances, and functions are all fine.
singletonsOnly :: OptionsMonad q => q [Dec] -> q [Dec]
singletonsOnly :: forall (q :: * -> *). OptionsMonad q => q [Dec] -> q [Dec]
singletonsOnly q [Dec]
qdecs = do
  Options
opts <- q Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  Options -> OptionsM q [Dec] -> q [Dec]
forall (m :: * -> *) a. Options -> OptionsM m a -> m a
withOptions Options
opts{genQuotedDecs :: Bool
genQuotedDecs = Bool
False} (OptionsM q [Dec] -> q [Dec]) -> OptionsM q [Dec] -> q [Dec]
forall a b. (a -> b) -> a -> b
$ OptionsM q [Dec] -> OptionsM q [Dec]
forall (q :: * -> *). OptionsMonad q => q [Dec] -> q [Dec]
singletons' (OptionsM q [Dec] -> OptionsM q [Dec])
-> OptionsM q [Dec] -> OptionsM q [Dec]
forall a b. (a -> b) -> a -> b
$ q [Dec] -> OptionsM q [Dec]
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift q [Dec]
qdecs

-- The workhorse for 'singletons' and 'singletonsOnly'. The difference between
-- the two functions is whether 'genQuotedDecs' is set to 'True' or 'False'.
singletons' :: OptionsMonad q => q [Dec] -> q [Dec]
singletons' :: forall (q :: * -> *). OptionsMonad q => q [Dec] -> q [Dec]
singletons' q [Dec]
qdecs = do
  Options
opts     <- q Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  [Dec]
decs     <- q [Dec]
qdecs
  [DDec]
ddecs    <- [Dec] -> DsM q [DDec] -> q [DDec]
forall (q :: * -> *) a. DsMonad q => [Dec] -> DsM q a -> q a
withLocalDeclarations [Dec]
decs (DsM q [DDec] -> q [DDec]) -> DsM q [DDec] -> q [DDec]
forall a b. (a -> b) -> a -> b
$ [Dec] -> DsM q [DDec]
forall (q :: * -> *). DsMonad q => [Dec] -> q [DDec]
dsDecs [Dec]
decs
  [DDec]
singDecs <- [Dec] -> [DDec] -> q [DDec]
forall (q :: * -> *). OptionsMonad q => [Dec] -> [DDec] -> q [DDec]
singTopLevelDecs [Dec]
decs [DDec]
ddecs
  let origDecs :: [Dec]
origDecs | Options -> Bool
genQuotedDecs Options
opts = [Dec]
decs
               | Bool
otherwise          = []
  [Dec] -> q [Dec]
forall (m :: * -> *) a. Monad m => a -> m a
return ([Dec] -> q [Dec]) -> [Dec] -> q [Dec]
forall a b. (a -> b) -> a -> b
$ [Dec]
origDecs [Dec] -> [Dec] -> [Dec]
forall a. [a] -> [a] -> [a]
++ [DDec] -> [Dec]
decsToTH [DDec]
singDecs

-- | Create instances of 'SEq' for the given types
singEqInstances :: OptionsMonad q => [Name] -> q [Dec]
singEqInstances :: forall (q :: * -> *). OptionsMonad q => [Name] -> q [Dec]
singEqInstances = (Name -> q [Dec]) -> [Name] -> q [Dec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM Name -> q [Dec]
forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singEqInstance

-- | Create instance of 'SEq' for the given type
singEqInstance :: OptionsMonad q => Name -> q [Dec]
singEqInstance :: forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singEqInstance = DerivDesc q -> String -> Name -> q [Dec]
forall (q :: * -> *).
OptionsMonad q =>
DerivDesc q -> String -> Name -> q [Dec]
singInstance DerivDesc q
forall (q :: * -> *). DsMonad q => DerivDesc q
mkEqInstance String
"Eq"

-- | Create instances of 'SDecide', 'TestEquality', and 'TestCoercion' for each
-- type in the list.
singDecideInstances :: OptionsMonad q => [Name] -> q [Dec]
singDecideInstances :: forall (q :: * -> *). OptionsMonad q => [Name] -> q [Dec]
singDecideInstances = (Name -> q [Dec]) -> [Name] -> q [Dec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM Name -> q [Dec]
forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singDecideInstance

-- | Create instances of 'SDecide', 'TestEquality', and 'TestCoercion' for the
-- given type.
singDecideInstance :: OptionsMonad q => Name -> q [Dec]
singDecideInstance :: forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singDecideInstance Name
name = do
  ([TyVarBndrUnit]
tvbs, [Con]
cons) <- String -> Name -> q ([TyVarBndrUnit], [Con])
forall (q :: * -> *).
DsMonad q =>
String -> Name -> q ([TyVarBndrUnit], [Con])
getDataD (String
"I cannot make an instance of SDecide for it.") Name
name
  [DTyVarBndrUnit]
dtvbs <- (TyVarBndrUnit -> q DTyVarBndrUnit)
-> [TyVarBndrUnit] -> q [DTyVarBndrUnit]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM TyVarBndrUnit -> q DTyVarBndrUnit
forall (q :: * -> *).
DsMonad q =>
TyVarBndrUnit -> q DTyVarBndrUnit
dsTvbUnit [TyVarBndrUnit]
tvbs
  let data_ty :: DType
data_ty = DType -> [DTyVarBndrUnit] -> DType
forall flag. DType -> [DTyVarBndr flag] -> DType
foldTypeTvbs (Name -> DType
DConT Name
name) [DTyVarBndrUnit]
dtvbs
  [DCon]
dcons <- (Con -> q [DCon]) -> [Con] -> q [DCon]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM ([DTyVarBndrUnit] -> DType -> Con -> q [DCon]
forall (q :: * -> *).
DsMonad q =>
[DTyVarBndrUnit] -> DType -> Con -> q [DCon]
dsCon [DTyVarBndrUnit]
dtvbs DType
data_ty) [Con]
cons
  let tyvars :: [DType]
tyvars = (DTyVarBndrUnit -> DType) -> [DTyVarBndrUnit] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map (Name -> DType
DVarT (Name -> DType)
-> (DTyVarBndrUnit -> Name) -> DTyVarBndrUnit -> DType
forall b c a. (b -> c) -> (a -> b) -> a -> c
. DTyVarBndrUnit -> Name
forall flag. DTyVarBndr flag -> Name
extractTvbName) [DTyVarBndrUnit]
dtvbs
      kind :: DType
kind = DType -> [DType] -> DType
foldType (Name -> DType
DConT Name
name) [DType]
tyvars
  ([DCon]
scons, [DDec]
_) <- [Dec] -> SgM [DCon] -> q ([DCon], [DDec])
forall (q :: * -> *) a.
OptionsMonad q =>
[Dec] -> SgM a -> q (a, [DDec])
singM [] (SgM [DCon] -> q ([DCon], [DDec]))
-> SgM [DCon] -> q ([DCon], [DDec])
forall a b. (a -> b) -> a -> b
$ (DCon -> SgM DCon) -> [DCon] -> SgM [DCon]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Name -> DCon -> SgM DCon
singCtor Name
name) [DCon]
dcons
  DDec
sDecideInstance <- Maybe [DType] -> DType -> [DCon] -> [DCon] -> q DDec
forall (q :: * -> *).
DsMonad q =>
Maybe [DType] -> DType -> [DCon] -> [DCon] -> q DDec
mkDecideInstance Maybe [DType]
forall a. Maybe a
Nothing DType
kind [DCon]
dcons [DCon]
scons
  [DDec]
testInstances <- (TestInstance -> q DDec) -> [TestInstance] -> q [DDec]
forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
(a -> f b) -> t a -> f (t b)
traverse (Maybe [DType] -> DType -> Name -> [DCon] -> TestInstance -> q DDec
forall (q :: * -> *).
OptionsMonad q =>
Maybe [DType] -> DType -> Name -> [DCon] -> TestInstance -> q DDec
mkTestInstance Maybe [DType]
forall a. Maybe a
Nothing DType
kind Name
name [DCon]
dcons)
                            [TestInstance
TestEquality, TestInstance
TestCoercion]
  [Dec] -> q [Dec]
forall (m :: * -> *) a. Monad m => a -> m a
return ([Dec] -> q [Dec]) -> [Dec] -> q [Dec]
forall a b. (a -> b) -> a -> b
$ [DDec] -> [Dec]
decsToTH (DDec
sDecideInstanceDDec -> [DDec] -> [DDec]
forall a. a -> [a] -> [a]
:[DDec]
testInstances)

-- | Create instances of 'SOrd' for the given types
singOrdInstances :: OptionsMonad q => [Name] -> q [Dec]
singOrdInstances :: forall (q :: * -> *). OptionsMonad q => [Name] -> q [Dec]
singOrdInstances = (Name -> q [Dec]) -> [Name] -> q [Dec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM Name -> q [Dec]
forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singOrdInstance

-- | Create instance of 'SOrd' for the given type
singOrdInstance :: OptionsMonad q => Name -> q [Dec]
singOrdInstance :: forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singOrdInstance = DerivDesc q -> String -> Name -> q [Dec]
forall (q :: * -> *).
OptionsMonad q =>
DerivDesc q -> String -> Name -> q [Dec]
singInstance DerivDesc q
forall (q :: * -> *). DsMonad q => DerivDesc q
mkOrdInstance String
"Ord"

-- | Create instances of 'SBounded' for the given types
singBoundedInstances :: OptionsMonad q => [Name] -> q [Dec]
singBoundedInstances :: forall (q :: * -> *). OptionsMonad q => [Name] -> q [Dec]
singBoundedInstances = (Name -> q [Dec]) -> [Name] -> q [Dec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM Name -> q [Dec]
forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singBoundedInstance

-- | Create instance of 'SBounded' for the given type
singBoundedInstance :: OptionsMonad q => Name -> q [Dec]
singBoundedInstance :: forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singBoundedInstance = DerivDesc q -> String -> Name -> q [Dec]
forall (q :: * -> *).
OptionsMonad q =>
DerivDesc q -> String -> Name -> q [Dec]
singInstance DerivDesc q
forall (q :: * -> *). DsMonad q => DerivDesc q
mkBoundedInstance String
"Bounded"

-- | Create instances of 'SEnum' for the given types
singEnumInstances :: OptionsMonad q => [Name] -> q [Dec]
singEnumInstances :: forall (q :: * -> *). OptionsMonad q => [Name] -> q [Dec]
singEnumInstances = (Name -> q [Dec]) -> [Name] -> q [Dec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM Name -> q [Dec]
forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singEnumInstance

-- | Create instance of 'SEnum' for the given type
singEnumInstance :: OptionsMonad q => Name -> q [Dec]
singEnumInstance :: forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singEnumInstance = DerivDesc q -> String -> Name -> q [Dec]
forall (q :: * -> *).
OptionsMonad q =>
DerivDesc q -> String -> Name -> q [Dec]
singInstance DerivDesc q
forall (q :: * -> *). DsMonad q => DerivDesc q
mkEnumInstance String
"Enum"

-- | Create instance of 'SShow' for the given type
--
-- (Not to be confused with 'showShowInstance'.)
singShowInstance :: OptionsMonad q => Name -> q [Dec]
singShowInstance :: forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singShowInstance = DerivDesc q -> String -> Name -> q [Dec]
forall (q :: * -> *).
OptionsMonad q =>
DerivDesc q -> String -> Name -> q [Dec]
singInstance DerivDesc q
forall (q :: * -> *). OptionsMonad q => DerivDesc q
mkShowInstance String
"Show"

-- | Create instances of 'SShow' for the given types
--
-- (Not to be confused with 'showSingInstances'.)
singShowInstances :: OptionsMonad q => [Name] -> q [Dec]
singShowInstances :: forall (q :: * -> *). OptionsMonad q => [Name] -> q [Dec]
singShowInstances = (Name -> q [Dec]) -> [Name] -> q [Dec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM Name -> q [Dec]
forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
singShowInstance

-- | Create instance of 'Show' for the given singleton type
--
-- (Not to be confused with 'singShowInstance'.)
showSingInstance :: OptionsMonad q => Name -> q [Dec]
showSingInstance :: forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
showSingInstance Name
name = do
  ([TyVarBndrUnit]
tvbs, [Con]
cons) <- String -> Name -> q ([TyVarBndrUnit], [Con])
forall (q :: * -> *).
DsMonad q =>
String -> Name -> q ([TyVarBndrUnit], [Con])
getDataD (String
"I cannot make an instance of Show for it.") Name
name
  [DTyVarBndrUnit]
dtvbs <- (TyVarBndrUnit -> q DTyVarBndrUnit)
-> [TyVarBndrUnit] -> q [DTyVarBndrUnit]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM TyVarBndrUnit -> q DTyVarBndrUnit
forall (q :: * -> *).
DsMonad q =>
TyVarBndrUnit -> q DTyVarBndrUnit
dsTvbUnit [TyVarBndrUnit]
tvbs
  let data_ty :: DType
data_ty = DType -> [DTyVarBndrUnit] -> DType
forall flag. DType -> [DTyVarBndr flag] -> DType
foldTypeTvbs (Name -> DType
DConT Name
name) [DTyVarBndrUnit]
dtvbs
  [DCon]
dcons <- (Con -> q [DCon]) -> [Con] -> q [DCon]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM ([DTyVarBndrUnit] -> DType -> Con -> q [DCon]
forall (q :: * -> *).
DsMonad q =>
[DTyVarBndrUnit] -> DType -> Con -> q [DCon]
dsCon [DTyVarBndrUnit]
dtvbs DType
data_ty) [Con]
cons
  let tyvars :: [DType]
tyvars    = (DTyVarBndrUnit -> DType) -> [DTyVarBndrUnit] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map (Name -> DType
DVarT (Name -> DType)
-> (DTyVarBndrUnit -> Name) -> DTyVarBndrUnit -> DType
forall b c a. (b -> c) -> (a -> b) -> a -> c
. DTyVarBndrUnit -> Name
forall flag. DTyVarBndr flag -> Name
extractTvbName) [DTyVarBndrUnit]
dtvbs
      kind :: DType
kind      = DType -> [DType] -> DType
foldType (Name -> DType
DConT Name
name) [DType]
tyvars
      data_decl :: DataDecl
data_decl = Name -> [DTyVarBndrUnit] -> [DCon] -> DataDecl
DataDecl Name
name [DTyVarBndrUnit]
dtvbs [DCon]
dcons
      deriv_show_decl :: DerivedDecl cls
deriv_show_decl = DerivedDecl :: forall (cls :: * -> Constraint).
Maybe [DType] -> DType -> Name -> DataDecl -> DerivedDecl cls
DerivedDecl { ded_mb_cxt :: Maybe [DType]
ded_mb_cxt     = Maybe [DType]
forall a. Maybe a
Nothing
                                    , ded_type :: DType
ded_type       = DType
kind
                                    , ded_type_tycon :: Name
ded_type_tycon = Name
name
                                    , ded_decl :: DataDecl
ded_decl       = DataDecl
data_decl }
  ([DDec]
show_insts, [DDec]
_) <- [Dec] -> SgM [DDec] -> q ([DDec], [DDec])
forall (q :: * -> *) a.
OptionsMonad q =>
[Dec] -> SgM a -> q (a, [DDec])
singM [] (SgM [DDec] -> q ([DDec], [DDec]))
-> SgM [DDec] -> q ([DDec], [DDec])
forall a b. (a -> b) -> a -> b
$ DerivedShowDecl -> SgM [DDec]
singDerivedShowDecs DerivedShowDecl
forall {cls :: * -> Constraint}. DerivedDecl cls
deriv_show_decl
  [Dec] -> q [Dec]
forall (f :: * -> *) a. Applicative f => a -> f a
pure ([Dec] -> q [Dec]) -> [Dec] -> q [Dec]
forall a b. (a -> b) -> a -> b
$ [DDec] -> [Dec]
decsToTH [DDec]
show_insts

-- | Create instances of 'Show' for the given singleton types
--
-- (Not to be confused with 'singShowInstances'.)
showSingInstances :: OptionsMonad q => [Name] -> q [Dec]
showSingInstances :: forall (q :: * -> *). OptionsMonad q => [Name] -> q [Dec]
showSingInstances = (Name -> q [Dec]) -> [Name] -> q [Dec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM Name -> q [Dec]
forall (q :: * -> *). OptionsMonad q => Name -> q [Dec]
showSingInstance

-- | Create an instance for @'SingI' TyCon{N}@, where @N@ is the positive
-- number provided as an argument.
--
-- Note that the generated code requires the use of the @QuantifiedConstraints@
-- language extension.
singITyConInstances :: DsMonad q => [Int] -> q [Dec]
singITyConInstances :: forall (q :: * -> *). DsMonad q => [Int] -> q [Dec]
singITyConInstances = (Int -> q Dec) -> [Int] -> q [Dec]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Int -> q Dec
forall (q :: * -> *). DsMonad q => Int -> q Dec
singITyConInstance

-- | Create an instance for @'SingI' TyCon{N}@, where @N@ is the positive
-- number provided as an argument.
--
-- Note that the generated code requires the use of the @QuantifiedConstraints@
-- language extension.
singITyConInstance :: DsMonad q => Int -> q Dec
singITyConInstance :: forall (q :: * -> *). DsMonad q => Int -> q Dec
singITyConInstance Int
n
  | Int
n Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
<= Int
0
  = String -> q Dec
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String -> q Dec) -> String -> q Dec
forall a b. (a -> b) -> a -> b
$ String
"Argument must be a positive number (given " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Int -> String
forall a. Show a => a -> String
show Int
n String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
")"
  | Bool
otherwise
  = do [Name]
as <- Int -> q Name -> q [Name]
forall (m :: * -> *) a. Applicative m => Int -> m a -> m [a]
replicateM Int
n (String -> q Name
forall (m :: * -> *). Quasi m => String -> m Name
qNewName String
"a")
       [Name]
ks <- Int -> q Name -> q [Name]
forall (m :: * -> *) a. Applicative m => Int -> m a -> m [a]
replicateM Int
n (String -> q Name
forall (m :: * -> *). Quasi m => String -> m Name
qNewName String
"k")
       Name
k_last <- String -> q Name
forall (m :: * -> *). Quasi m => String -> m Name
qNewName String
"k_last"
       Name
f      <- String -> q Name
forall (m :: * -> *). Quasi m => String -> m Name
qNewName String
"f"
       Name
x      <- String -> q Name
forall (m :: * -> *). Quasi m => String -> m Name
qNewName String
"x"
       let k_penult :: Name
k_penult = [Name] -> Name
forall a. [a] -> a
last [Name]
ks
           k_fun :: DType
k_fun = [DTyVarBndrSpec] -> [DType] -> [DType] -> DType -> DType
ravelVanillaDType [] [] ((Name -> DType) -> [Name] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map Name -> DType
DVarT [Name]
ks) (Name -> DType
DVarT Name
k_last)
           f_ty :: DType
f_ty  = Name -> DType
DVarT Name
f
           a_tys :: [DType]
a_tys = (Name -> DType) -> [Name] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map Name -> DType
DVarT [Name]
as
           mk_fun :: DType -> DType -> DType -> DType
mk_fun DType
arrow DType
t1 DType
t2 = DType
arrow DType -> DType -> DType
`DAppT` DType
t1 DType -> DType -> DType
`DAppT` DType
t2
           matchable_apply_fun :: DType
matchable_apply_fun   = DType -> DType -> DType -> DType
mk_fun DType
DArrowT                (Name -> DType
DVarT Name
k_penult) (Name -> DType
DVarT Name
k_last)
           unmatchable_apply_fun :: DType
unmatchable_apply_fun = DType -> DType -> DType -> DType
mk_fun (Name -> DType
DConT Name
tyFunArrowName) (Name -> DType
DVarT Name
k_penult) (Name -> DType
DVarT Name
k_last)
           ctxt :: [DType]
ctxt = [ DForallTelescope -> DType -> DType
DForallT ([DTyVarBndrSpec] -> DForallTelescope
DForallInvis ((Name -> DTyVarBndrSpec) -> [Name] -> [DTyVarBndrSpec]
forall a b. (a -> b) -> [a] -> [b]
map (Name -> Specificity -> DTyVarBndrSpec
forall flag. Name -> flag -> DTyVarBndr flag
`DPlainTV` Specificity
SpecifiedSpec) [Name]
as)) (DType -> DType) -> DType -> DType
forall a b. (a -> b) -> a -> b
$
                    [DType] -> DType -> DType
DConstrainedT ((DType -> DType) -> [DType] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map (DType -> DType -> DType
DAppT (Name -> DType
DConT Name
singIName)) [DType]
a_tys)
                                  (Name -> DType
DConT Name
singIName DType -> DType -> DType
`DAppT` DType -> [DType] -> DType
foldType DType
f_ty [DType]
a_tys)
                  , Name -> DType
DConT Name
equalityName
                      DType -> DType -> DType
`DAppT` (Name -> DType
DConT Name
applyTyConName DType -> DType -> DType
`DSigT`
                                DType -> DType -> DType -> DType
mk_fun DType
DArrowT DType
matchable_apply_fun DType
unmatchable_apply_fun)
                      DType -> DType -> DType
`DAppT` Name -> DType
DConT Name
applyTyConAux1Name
                  ]
       Dec -> q Dec
forall (f :: * -> *) a. Applicative f => a -> f a
pure (Dec -> q Dec) -> Dec -> q Dec
forall a b. (a -> b) -> a -> b
$ DDec -> Dec
decToTH
            (DDec -> Dec) -> DDec -> Dec
forall a b. (a -> b) -> a -> b
$ Maybe Overlap
-> Maybe [DTyVarBndrUnit] -> [DType] -> DType -> [DDec] -> DDec
DInstanceD
                Maybe Overlap
forall a. Maybe a
Nothing Maybe [DTyVarBndrUnit]
forall a. Maybe a
Nothing [DType]
ctxt
                (Name -> DType
DConT Name
singIName DType -> DType -> DType
`DAppT` (Name -> DType
DConT (Int -> Name
mkTyConName Int
n) DType -> DType -> DType
`DAppT` (DType
f_ty DType -> DType -> DType
`DSigT` DType
k_fun)))
                [DLetDec -> DDec
DLetDec (DLetDec -> DDec) -> DLetDec -> DDec
forall a b. (a -> b) -> a -> b
$ Name -> [DClause] -> DLetDec
DFunD Name
singMethName
                           [[DPat] -> DExp -> DClause
DClause [] (DExp -> DClause) -> DExp -> DClause
forall a b. (a -> b) -> a -> b
$
                            Int -> DType -> DExp -> DExp
wrapSingFun Int
1 DType
DWildCardT (DExp -> DExp) -> DExp -> DExp
forall a b. (a -> b) -> a -> b
$
                            [Name] -> DExp -> DExp
DLamE [Name
x] (DExp -> DExp) -> DExp -> DExp
forall a b. (a -> b) -> a -> b
$
                            Name -> DExp
DVarE Name
withSingIName DExp -> DExp -> DExp
`DAppE` Name -> DExp
DVarE Name
x
                                                DExp -> DExp -> DExp
`DAppE` Name -> DExp
DVarE Name
singMethName]]

singInstance :: OptionsMonad q => DerivDesc q -> String -> Name -> q [Dec]
singInstance :: forall (q :: * -> *).
OptionsMonad q =>
DerivDesc q -> String -> Name -> q [Dec]
singInstance DerivDesc q
mk_inst String
inst_name Name
name = do
  ([TyVarBndrUnit]
tvbs, [Con]
cons) <- String -> Name -> q ([TyVarBndrUnit], [Con])
forall (q :: * -> *).
DsMonad q =>
String -> Name -> q ([TyVarBndrUnit], [Con])
getDataD (String
"I cannot make an instance of " String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
inst_name
                            String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
" for it.") Name
name
  [DTyVarBndrUnit]
dtvbs <- (TyVarBndrUnit -> q DTyVarBndrUnit)
-> [TyVarBndrUnit] -> q [DTyVarBndrUnit]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM TyVarBndrUnit -> q DTyVarBndrUnit
forall (q :: * -> *).
DsMonad q =>
TyVarBndrUnit -> q DTyVarBndrUnit
dsTvbUnit [TyVarBndrUnit]
tvbs
  let data_ty :: DType
data_ty = DType -> [DTyVarBndrUnit] -> DType
forall flag. DType -> [DTyVarBndr flag] -> DType
foldTypeTvbs (Name -> DType
DConT Name
name) [DTyVarBndrUnit]
dtvbs
  [DCon]
dcons <- (Con -> q [DCon]) -> [Con] -> q [DCon]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM ([DTyVarBndrUnit] -> DType -> Con -> q [DCon]
forall (q :: * -> *).
DsMonad q =>
[DTyVarBndrUnit] -> DType -> Con -> q [DCon]
dsCon [DTyVarBndrUnit]
dtvbs DType
data_ty) [Con]
cons
  let data_decl :: DataDecl
data_decl = Name -> [DTyVarBndrUnit] -> [DCon] -> DataDecl
DataDecl Name
name [DTyVarBndrUnit]
dtvbs [DCon]
dcons
  UInstDecl
raw_inst <- DerivDesc q
mk_inst Maybe [DType]
forall a. Maybe a
Nothing DType
data_ty DataDecl
data_decl
  (AInstDecl
a_inst, [DDec]
decs) <- [Dec] -> PrM AInstDecl -> q (AInstDecl, [DDec])
forall (q :: * -> *) a.
OptionsMonad q =>
[Dec] -> PrM a -> q (a, [DDec])
promoteM [] (PrM AInstDecl -> q (AInstDecl, [DDec]))
-> PrM AInstDecl -> q (AInstDecl, [DDec])
forall a b. (a -> b) -> a -> b
$
                    OMap Name DType
-> Map Name [DTyVarBndrUnit] -> UInstDecl -> PrM AInstDecl
promoteInstanceDec OMap Name DType
forall k v. OMap k v
OMap.empty Map Name [DTyVarBndrUnit]
forall k a. Map k a
Map.empty UInstDecl
raw_inst
  [DDec]
decs' <- [Dec] -> SgM [DDec] -> q [DDec]
forall (q :: * -> *).
OptionsMonad q =>
[Dec] -> SgM [DDec] -> q [DDec]
singDecsM [] (SgM [DDec] -> q [DDec]) -> SgM [DDec] -> q [DDec]
forall a b. (a -> b) -> a -> b
$ (DDec -> [DDec] -> [DDec]
forall a. a -> [a] -> [a]
:[]) (DDec -> [DDec]) -> SgM DDec -> SgM [DDec]
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> AInstDecl -> SgM DDec
singInstD AInstDecl
a_inst
  [Dec] -> q [Dec]
forall (m :: * -> *) a. Monad m => a -> m a
return ([Dec] -> q [Dec]) -> [Dec] -> q [Dec]
forall a b. (a -> b) -> a -> b
$ [DDec] -> [Dec]
decsToTH ([DDec]
decs [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
decs')

singInfo :: OptionsMonad q => DInfo -> q [DDec]
singInfo :: forall (q :: * -> *). OptionsMonad q => DInfo -> q [DDec]
singInfo (DTyConI DDec
dec Maybe [DDec]
_) =
  [Dec] -> [DDec] -> q [DDec]
forall (q :: * -> *). OptionsMonad q => [Dec] -> [DDec] -> q [DDec]
singTopLevelDecs [] [DDec
dec]
singInfo (DPrimTyConI Name
_name Int
_numArgs Bool
_unlifted) =
  String -> q [DDec]
forall (m :: * -> *) a. MonadFail m => String -> m a
fail String
"Singling of primitive type constructors not supported"
singInfo (DVarI Name
_name DType
_ty Maybe Name
_mdec) =
  String -> q [DDec]
forall (m :: * -> *) a. MonadFail m => String -> m a
fail String
"Singling of value info not supported"
singInfo (DTyVarI Name
_name DType
_ty) =
  String -> q [DDec]
forall (m :: * -> *) a. MonadFail m => String -> m a
fail String
"Singling of type variable info not supported"
singInfo (DPatSynI {}) =
  String -> q [DDec]
forall (m :: * -> *) a. MonadFail m => String -> m a
fail String
"Singling of pattern synonym info not supported"

singTopLevelDecs :: OptionsMonad q => [Dec] -> [DDec] -> q [DDec]
singTopLevelDecs :: forall (q :: * -> *). OptionsMonad q => [Dec] -> [DDec] -> q [DDec]
singTopLevelDecs [Dec]
locals [DDec]
raw_decls = [Dec] -> DsM q [DDec] -> q [DDec]
forall (q :: * -> *) a. DsMonad q => [Dec] -> DsM q a -> q a
withLocalDeclarations [Dec]
locals (DsM q [DDec] -> q [DDec]) -> DsM q [DDec] -> q [DDec]
forall a b. (a -> b) -> a -> b
$ do
  [DDec]
decls <- [DDec] -> DsM q [DDec]
forall (q :: * -> *) a. (DsMonad q, Data a) => a -> q a
expand [DDec]
raw_decls     -- expand type synonyms
  PDecs { pd_let_decs :: PartitionedDecs -> [DLetDec]
pd_let_decs                = [DLetDec]
letDecls
        , pd_class_decs :: PartitionedDecs -> [UClassDecl]
pd_class_decs              = [UClassDecl]
classes
        , pd_instance_decs :: PartitionedDecs -> [UInstDecl]
pd_instance_decs           = [UInstDecl]
insts
        , pd_data_decs :: PartitionedDecs -> [DataDecl]
pd_data_decs               = [DataDecl]
datas
        , pd_ty_syn_decs :: PartitionedDecs -> [TySynDecl]
pd_ty_syn_decs             = [TySynDecl]
ty_syns
        , pd_open_type_family_decs :: PartitionedDecs -> [OpenTypeFamilyDecl]
pd_open_type_family_decs   = [OpenTypeFamilyDecl]
o_tyfams
        , pd_closed_type_family_decs :: PartitionedDecs -> [ClosedTypeFamilyDecl]
pd_closed_type_family_decs = [ClosedTypeFamilyDecl]
c_tyfams
        , pd_derived_eq_decs :: PartitionedDecs -> [DerivedEqDecl]
pd_derived_eq_decs         = [DerivedEqDecl]
derivedEqDecs
        , pd_derived_show_decs :: PartitionedDecs -> [DerivedShowDecl]
pd_derived_show_decs       = [DerivedShowDecl]
derivedShowDecs } <- [DDec] -> DsM q PartitionedDecs
forall (m :: * -> *). OptionsMonad m => [DDec] -> m PartitionedDecs
partitionDecs [DDec]
decls

  ((ALetDecEnv
letDecEnv, [AClassDecl]
classes', [AInstDecl]
insts'), [DDec]
promDecls) <- [Dec]
-> PrM (ALetDecEnv, [AClassDecl], [AInstDecl])
-> DsM q ((ALetDecEnv, [AClassDecl], [AInstDecl]), [DDec])
forall (q :: * -> *) a.
OptionsMonad q =>
[Dec] -> PrM a -> q (a, [DDec])
promoteM [Dec]
locals (PrM (ALetDecEnv, [AClassDecl], [AInstDecl])
 -> DsM q ((ALetDecEnv, [AClassDecl], [AInstDecl]), [DDec]))
-> PrM (ALetDecEnv, [AClassDecl], [AInstDecl])
-> DsM q ((ALetDecEnv, [AClassDecl], [AInstDecl]), [DDec])
forall a b. (a -> b) -> a -> b
$ do
    [TySynDecl]
-> [ClosedTypeFamilyDecl] -> [OpenTypeFamilyDecl] -> PrM ()
defunTopLevelTypeDecls [TySynDecl]
ty_syns [ClosedTypeFamilyDecl]
c_tyfams [OpenTypeFamilyDecl]
o_tyfams
    [DLetDec]
recSelLetDecls <- [DataDecl] -> PrM [DLetDec]
promoteDataDecs [DataDecl]
datas
    ([LetBind]
_, ALetDecEnv
letDecEnv) <- Maybe Integer -> [DLetDec] -> PrM ([LetBind], ALetDecEnv)
promoteLetDecs Maybe Integer
forall a. Maybe a
Nothing ([DLetDec] -> PrM ([LetBind], ALetDecEnv))
-> [DLetDec] -> PrM ([LetBind], ALetDecEnv)
forall a b. (a -> b) -> a -> b
$ [DLetDec]
recSelLetDecls [DLetDec] -> [DLetDec] -> [DLetDec]
forall a. [a] -> [a] -> [a]
++ [DLetDec]
letDecls
    [AClassDecl]
classes' <- (UClassDecl -> PrM AClassDecl) -> [UClassDecl] -> PrM [AClassDecl]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM UClassDecl -> PrM AClassDecl
promoteClassDec [UClassDecl]
classes
    let meth_sigs :: OMap Name DType
meth_sigs    = (UClassDecl -> OMap Name DType) -> [UClassDecl] -> OMap Name DType
forall (t :: * -> *) m a.
(Foldable t, Monoid m) =>
(a -> m) -> t a -> m
foldMap (LetDecEnv Unannotated -> OMap Name DType
forall (ann :: AnnotationFlag). LetDecEnv ann -> OMap Name DType
lde_types (LetDecEnv Unannotated -> OMap Name DType)
-> (UClassDecl -> LetDecEnv Unannotated)
-> UClassDecl
-> OMap Name DType
forall b c a. (b -> c) -> (a -> b) -> a -> c
. UClassDecl -> LetDecEnv Unannotated
forall (ann :: AnnotationFlag). ClassDecl ann -> LetDecEnv ann
cd_lde) [UClassDecl]
classes
        cls_tvbs_map :: Map Name [DTyVarBndrUnit]
cls_tvbs_map = [(Name, [DTyVarBndrUnit])] -> Map Name [DTyVarBndrUnit]
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList ([(Name, [DTyVarBndrUnit])] -> Map Name [DTyVarBndrUnit])
-> [(Name, [DTyVarBndrUnit])] -> Map Name [DTyVarBndrUnit]
forall a b. (a -> b) -> a -> b
$ (UClassDecl -> (Name, [DTyVarBndrUnit]))
-> [UClassDecl] -> [(Name, [DTyVarBndrUnit])]
forall a b. (a -> b) -> [a] -> [b]
map (\UClassDecl
cd -> (UClassDecl -> Name
forall (ann :: AnnotationFlag). ClassDecl ann -> Name
cd_name UClassDecl
cd, UClassDecl -> [DTyVarBndrUnit]
forall (ann :: AnnotationFlag). ClassDecl ann -> [DTyVarBndrUnit]
cd_tvbs UClassDecl
cd)) [UClassDecl]
classes
    [AInstDecl]
insts' <- (UInstDecl -> PrM AInstDecl) -> [UInstDecl] -> PrM [AInstDecl]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (OMap Name DType
-> Map Name [DTyVarBndrUnit] -> UInstDecl -> PrM AInstDecl
promoteInstanceDec OMap Name DType
meth_sigs Map Name [DTyVarBndrUnit]
cls_tvbs_map) [UInstDecl]
insts
    (ALetDecEnv, [AClassDecl], [AInstDecl])
-> PrM (ALetDecEnv, [AClassDecl], [AInstDecl])
forall (m :: * -> *) a. Monad m => a -> m a
return (ALetDecEnv
letDecEnv, [AClassDecl]
classes', [AInstDecl]
insts')

  [Dec] -> SgM [DDec] -> DsM q [DDec]
forall (q :: * -> *).
OptionsMonad q =>
[Dec] -> SgM [DDec] -> q [DDec]
singDecsM [Dec]
locals (SgM [DDec] -> DsM q [DDec]) -> SgM [DDec] -> DsM q [DDec]
forall a b. (a -> b) -> a -> b
$ do
    [(Name, DExp)]
dataLetBinds <- (DataDecl -> SgM [(Name, DExp)])
-> [DataDecl] -> SgM [(Name, DExp)]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM DataDecl -> SgM [(Name, DExp)]
forall (q :: * -> *).
OptionsMonad q =>
DataDecl -> q [(Name, DExp)]
buildDataLets [DataDecl]
datas
    [(Name, DExp)]
methLetBinds <- (UClassDecl -> SgM [(Name, DExp)])
-> [UClassDecl] -> SgM [(Name, DExp)]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM UClassDecl -> SgM [(Name, DExp)]
forall (q :: * -> *).
OptionsMonad q =>
UClassDecl -> q [(Name, DExp)]
buildMethLets [UClassDecl]
classes
    let letBinds :: [(Name, DExp)]
letBinds = [(Name, DExp)]
dataLetBinds [(Name, DExp)] -> [(Name, DExp)] -> [(Name, DExp)]
forall a. [a] -> [a] -> [a]
++ [(Name, DExp)]
methLetBinds
    ([DLetDec]
newLetDecls, [DDec]
singIDefunDecls, [DDec]
newDecls)
                            <- [(Name, DExp)]
-> SgM ([DLetDec], [DDec], [DDec])
-> SgM ([DLetDec], [DDec], [DDec])
forall a. [(Name, DExp)] -> SgM a -> SgM a
bindLets [(Name, DExp)]
letBinds (SgM ([DLetDec], [DDec], [DDec])
 -> SgM ([DLetDec], [DDec], [DDec]))
-> SgM ([DLetDec], [DDec], [DDec])
-> SgM ([DLetDec], [DDec], [DDec])
forall a b. (a -> b) -> a -> b
$
                               ALetDecEnv -> SgM [DDec] -> SgM ([DLetDec], [DDec], [DDec])
forall a. ALetDecEnv -> SgM a -> SgM ([DLetDec], [DDec], a)
singLetDecEnv ALetDecEnv
letDecEnv (SgM [DDec] -> SgM ([DLetDec], [DDec], [DDec]))
-> SgM [DDec] -> SgM ([DLetDec], [DDec], [DDec])
forall a b. (a -> b) -> a -> b
$ do
                                 [DDec]
newDataDecls <- (DataDecl -> SgM [DDec]) -> [DataDecl] -> SgM [DDec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM DataDecl -> SgM [DDec]
singDataD [DataDecl]
datas
                                 [DDec]
newClassDecls <- (AClassDecl -> SgM DDec) -> [AClassDecl] -> SgM [DDec]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM AClassDecl -> SgM DDec
singClassD [AClassDecl]
classes'
                                 [DDec]
newInstDecls <- (AInstDecl -> SgM DDec) -> [AInstDecl] -> SgM [DDec]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM AInstDecl -> SgM DDec
singInstD [AInstDecl]
insts'
                                 [DDec]
newDerivedEqDecs <- (DerivedEqDecl -> SgM [DDec]) -> [DerivedEqDecl] -> SgM [DDec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM DerivedEqDecl -> SgM [DDec]
singDerivedEqDecs [DerivedEqDecl]
derivedEqDecs
                                 [DDec]
newDerivedShowDecs <- (DerivedShowDecl -> SgM [DDec]) -> [DerivedShowDecl] -> SgM [DDec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM DerivedShowDecl -> SgM [DDec]
singDerivedShowDecs [DerivedShowDecl]
derivedShowDecs
                                 [DDec] -> SgM [DDec]
forall (m :: * -> *) a. Monad m => a -> m a
return ([DDec] -> SgM [DDec]) -> [DDec] -> SgM [DDec]
forall a b. (a -> b) -> a -> b
$ [DDec]
newDataDecls [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
newClassDecls
                                                       [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
newInstDecls
                                                       [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
newDerivedEqDecs
                                                       [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
newDerivedShowDecs
    [DDec] -> SgM [DDec]
forall (m :: * -> *) a. Monad m => a -> m a
return ([DDec] -> SgM [DDec]) -> [DDec] -> SgM [DDec]
forall a b. (a -> b) -> a -> b
$ [DDec]
promDecls [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ ((DLetDec -> DDec) -> [DLetDec] -> [DDec]
forall a b. (a -> b) -> [a] -> [b]
map DLetDec -> DDec
DLetDec [DLetDec]
newLetDecls) [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
singIDefunDecls [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
newDecls

-- see comment at top of file
buildDataLets :: OptionsMonad q => DataDecl -> q [(Name, DExp)]
buildDataLets :: forall (q :: * -> *).
OptionsMonad q =>
DataDecl -> q [(Name, DExp)]
buildDataLets (DataDecl Name
_name [DTyVarBndrUnit]
_tvbs [DCon]
cons) = do
  Options
opts <- q Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  [(Name, DExp)] -> q [(Name, DExp)]
forall (f :: * -> *) a. Applicative f => a -> f a
pure ([(Name, DExp)] -> q [(Name, DExp)])
-> [(Name, DExp)] -> q [(Name, DExp)]
forall a b. (a -> b) -> a -> b
$ (DCon -> [(Name, DExp)]) -> [DCon] -> [(Name, DExp)]
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap (Options -> DCon -> [(Name, DExp)]
con_num_args Options
opts) [DCon]
cons
  where
    con_num_args :: Options -> DCon -> [(Name, DExp)]
    con_num_args :: Options -> DCon -> [(Name, DExp)]
con_num_args Options
opts (DCon [DTyVarBndrSpec]
_tvbs [DType]
_cxt Name
name DConFields
fields DType
_rty) =
      (Name
name, Int -> DType -> DExp -> DExp
wrapSingFun ([DType] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (DConFields -> [DType]
tysOfConFields DConFields
fields))
                         (Name -> DType
DConT (Name -> DType) -> Name -> DType
forall a b. (a -> b) -> a -> b
$ Options -> Name -> Name
defunctionalizedName0 Options
opts Name
name)
                         (Name -> DExp
DConE (Name -> DExp) -> Name -> DExp
forall a b. (a -> b) -> a -> b
$ Options -> Name -> Name
singledDataConName Options
opts Name
name))
      (Name, DExp) -> [(Name, DExp)] -> [(Name, DExp)]
forall a. a -> [a] -> [a]
: Options -> DConFields -> [(Name, DExp)]
rec_selectors Options
opts DConFields
fields

    rec_selectors :: Options -> DConFields -> [(Name, DExp)]
    rec_selectors :: Options -> DConFields -> [(Name, DExp)]
rec_selectors Options
_    (DNormalC {}) = []
    rec_selectors Options
opts (DRecC [DVarBangType]
fields) =
      let names :: [Name]
names = (DVarBangType -> Name) -> [DVarBangType] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map DVarBangType -> Name
forall a b c. (a, b, c) -> a
fstOf3 [DVarBangType]
fields in
      [ (Name
name, Int -> DType -> DExp -> DExp
wrapSingFun Int
1 (Name -> DType
DConT (Name -> DType) -> Name -> DType
forall a b. (a -> b) -> a -> b
$ Options -> Name -> Name
defunctionalizedName0 Options
opts Name
name)
                             (Name -> DExp
DVarE (Name -> DExp) -> Name -> DExp
forall a b. (a -> b) -> a -> b
$ Options -> Name -> Name
singledValueName Options
opts Name
name))
      | Name
name <- [Name]
names ]

-- see comment at top of file
buildMethLets :: OptionsMonad q => UClassDecl -> q [(Name, DExp)]
buildMethLets :: forall (q :: * -> *).
OptionsMonad q =>
UClassDecl -> q [(Name, DExp)]
buildMethLets (ClassDecl { cd_lde :: forall (ann :: AnnotationFlag). ClassDecl ann -> LetDecEnv ann
cd_lde = LetDecEnv { lde_types :: forall (ann :: AnnotationFlag). LetDecEnv ann -> OMap Name DType
lde_types = OMap Name DType
meth_sigs } }) = do
  Options
opts <- q Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  [(Name, DExp)] -> q [(Name, DExp)]
forall (f :: * -> *) a. Applicative f => a -> f a
pure ([(Name, DExp)] -> q [(Name, DExp)])
-> [(Name, DExp)] -> q [(Name, DExp)]
forall a b. (a -> b) -> a -> b
$ (LetBind -> (Name, DExp)) -> [LetBind] -> [(Name, DExp)]
forall a b. (a -> b) -> [a] -> [b]
map (Options -> LetBind -> (Name, DExp)
mk_bind Options
opts) (OMap Name DType -> [LetBind]
forall k v. OMap k v -> [(k, v)]
OMap.assocs OMap Name DType
meth_sigs)
  where
    mk_bind :: Options -> LetBind -> (Name, DExp)
mk_bind Options
opts (Name
meth_name, DType
meth_ty) =
      ( Name
meth_name
      , Int -> DType -> DExp -> DExp
wrapSingFun (DType -> Int
countArgs DType
meth_ty) (Name -> DType
DConT (Name -> DType) -> Name -> DType
forall a b. (a -> b) -> a -> b
$ Options -> Name -> Name
defunctionalizedName0 Options
opts Name
meth_name)
                                        (Name -> DExp
DVarE (Name -> DExp) -> Name -> DExp
forall a b. (a -> b) -> a -> b
$ Options -> Name -> Name
singledValueName Options
opts Name
meth_name) )

singClassD :: AClassDecl -> SgM DDec
singClassD :: AClassDecl -> SgM DDec
singClassD (ClassDecl { cd_cxt :: forall (ann :: AnnotationFlag). ClassDecl ann -> [DType]
cd_cxt  = [DType]
cls_cxt
                      , cd_name :: forall (ann :: AnnotationFlag). ClassDecl ann -> Name
cd_name = Name
cls_name
                      , cd_tvbs :: forall (ann :: AnnotationFlag). ClassDecl ann -> [DTyVarBndrUnit]
cd_tvbs = [DTyVarBndrUnit]
cls_tvbs
                      , cd_fds :: forall (ann :: AnnotationFlag). ClassDecl ann -> [FunDep]
cd_fds  = [FunDep]
cls_fundeps
                      , cd_lde :: forall (ann :: AnnotationFlag). ClassDecl ann -> LetDecEnv ann
cd_lde  = LetDecEnv { lde_defns :: forall (ann :: AnnotationFlag).
LetDecEnv ann -> OMap Name (LetDecRHS ann)
lde_defns     = OMap Name (LetDecRHS Annotated)
default_defns
                                            , lde_types :: forall (ann :: AnnotationFlag). LetDecEnv ann -> OMap Name DType
lde_types     = OMap Name DType
meth_sigs
                                            , lde_infix :: forall (ann :: AnnotationFlag). LetDecEnv ann -> OMap Name Fixity
lde_infix     = OMap Name Fixity
fixities
                                            , lde_proms :: forall (ann :: AnnotationFlag).
LetDecEnv ann -> IfAnn ann (OMap Name DType) ()
lde_proms     = IfAnn Annotated (OMap Name DType) ()
promoted_defaults
                                            , lde_bound_kvs :: forall (ann :: AnnotationFlag).
LetDecEnv ann -> IfAnn ann (OMap Name (OSet Name)) ()
lde_bound_kvs = IfAnn Annotated (OMap Name (OSet Name)) ()
meth_bound_kvs } }) =
  [DType] -> SgM DDec -> SgM DDec
forall a. [DType] -> SgM a -> SgM a
bindContext [DType -> [DTyVarBndrUnit] -> DType
forall flag. DType -> [DTyVarBndr flag] -> DType
foldTypeTvbs (Name -> DType
DConT Name
cls_name) [DTyVarBndrUnit]
cls_tvbs] (SgM DDec -> SgM DDec) -> SgM DDec -> SgM DDec
forall a b. (a -> b) -> a -> b
$ do
    Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
    Maybe DType
mb_cls_sak <- Name -> SgM (Maybe DType)
forall (q :: * -> *). DsMonad q => Name -> q (Maybe DType)
dsReifyType Name
cls_name
    let sing_cls_name :: Name
sing_cls_name   = Options -> Name -> Name
singledClassName Options
opts Name
cls_name
        mb_sing_cls_sak :: Maybe DDec
mb_sing_cls_sak = (DType -> DDec) -> Maybe DType -> Maybe DDec
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (Name -> DType -> DDec
DKiSigD Name
sing_cls_name) Maybe DType
mb_cls_sak
    [DDec]
cls_infix_decls <- [Name] -> SgM [DDec]
forall (q :: * -> *). OptionsMonad q => [Name] -> q [DDec]
singReifiedInfixDecls ([Name] -> SgM [DDec]) -> [Name] -> SgM [DDec]
forall a b. (a -> b) -> a -> b
$ Name
cls_nameName -> [Name] -> [Name]
forall a. a -> [a] -> [a]
:[Name]
meth_names
    ([DLetDec]
sing_sigs, [(Name, DExp)]
_, [(Name, [Name])]
tyvar_names, [(Name, [DType])]
cxts, [Maybe DType]
res_kis, [[DDec]]
singIDefunss)
      <- [(DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
  Maybe DType, [DDec])]
-> ([DLetDec], [(Name, DExp)], [(Name, [Name])], [(Name, [DType])],
    [Maybe DType], [[DDec]])
forall a b c d e f.
[(a, b, c, d, e, f)] -> ([a], [b], [c], [d], [e], [f])
unzip6 ([(DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
   Maybe DType, [DDec])]
 -> ([DLetDec], [(Name, DExp)], [(Name, [Name])], [(Name, [DType])],
     [Maybe DType], [[DDec]]))
-> SgM
     [(DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
       Maybe DType, [DDec])]
-> SgM
     ([DLetDec], [(Name, DExp)], [(Name, [Name])], [(Name, [DType])],
      [Maybe DType], [[DDec]])
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (Name
 -> DType
 -> SgM
      (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
       Maybe DType, [DDec]))
-> [Name]
-> [DType]
-> SgM
     [(DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
       Maybe DType, [DDec])]
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m [c]
zipWithM (OMap Name (LetDecRHS Annotated)
-> OMap Name DType
-> OMap Name (OSet Name)
-> Name
-> DType
-> SgM
     (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
      Maybe DType, [DDec])
singTySig OMap Name (LetDecRHS Annotated)
forall {a}. a
no_meth_defns OMap Name DType
meth_sigs OMap Name (OSet Name)
IfAnn Annotated (OMap Name (OSet Name)) ()
meth_bound_kvs)
                             [Name]
meth_names
                             ((Name -> DType) -> [Name] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map (Name -> DType
DConT (Name -> DType) -> (Name -> Name) -> Name -> DType
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Options -> Name -> Name
defunctionalizedName0 Options
opts) [Name]
meth_names)
    [DDec] -> SgM ()
forall (m :: * -> *). MonadWriter [DDec] m => [DDec] -> m ()
emitDecs ([DDec] -> SgM ()) -> [DDec] -> SgM ()
forall a b. (a -> b) -> a -> b
$ Maybe DDec -> [DDec]
forall a. Maybe a -> [a]
maybeToList Maybe DDec
mb_sing_cls_sak [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
cls_infix_decls [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [[DDec]] -> [DDec]
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [[DDec]]
singIDefunss
    let default_sigs :: [DDec]
default_sigs = [Maybe DDec] -> [DDec]
forall a. [Maybe a] -> [a]
catMaybes ([Maybe DDec] -> [DDec]) -> [Maybe DDec] -> [DDec]
forall a b. (a -> b) -> a -> b
$
                       (Name -> DLetDec -> (Name, [Name]) -> Maybe DType -> Maybe DDec)
-> [Name]
-> [DLetDec]
-> [(Name, [Name])]
-> [Maybe DType]
-> [Maybe DDec]
forall a b c d e.
(a -> b -> c -> d -> e) -> [a] -> [b] -> [c] -> [d] -> [e]
zipWith4 (Options
-> Name -> DLetDec -> (Name, [Name]) -> Maybe DType -> Maybe DDec
forall {a}.
Options
-> Name -> DLetDec -> (a, [Name]) -> Maybe DType -> Maybe DDec
mk_default_sig Options
opts) [Name]
meth_names [DLetDec]
sing_sigs
                                                      [(Name, [Name])]
tyvar_names [Maybe DType]
res_kis
        res_ki_map :: Map Name DType
res_ki_map   = [LetBind] -> Map Name DType
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList ([Name] -> [DType] -> [LetBind]
forall a b. [a] -> [b] -> [(a, b)]
zip [Name]
meth_names
                                         ((Maybe DType -> DType) -> [Maybe DType] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map (DType -> Maybe DType -> DType
forall a. a -> Maybe a -> a
fromMaybe DType
forall {a}. a
always_sig) [Maybe DType]
res_kis))
    [DLetDec]
sing_meths <- ((Name, LetDecRHS Annotated) -> SgM DLetDec)
-> [(Name, LetDecRHS Annotated)] -> SgM [DLetDec]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((Name -> LetDecRHS Annotated -> SgM DLetDec)
-> (Name, LetDecRHS Annotated) -> SgM DLetDec
forall a b c. (a -> b -> c) -> (a, b) -> c
uncurry (Map Name [Name]
-> Map Name [DType]
-> Map Name DType
-> Name
-> LetDecRHS Annotated
-> SgM DLetDec
singLetDecRHS ([(Name, [Name])] -> Map Name [Name]
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList [(Name, [Name])]
tyvar_names)
                                               ([(Name, [DType])] -> Map Name [DType]
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList [(Name, [DType])]
cxts)
                                               Map Name DType
res_ki_map))
                       (OMap Name (LetDecRHS Annotated) -> [(Name, LetDecRHS Annotated)]
forall k v. OMap k v -> [(k, v)]
OMap.assocs OMap Name (LetDecRHS Annotated)
default_defns)
    [DLetDec]
fixities' <- ((Name, Fixity) -> SgM (Maybe DLetDec))
-> [(Name, Fixity)] -> SgM [DLetDec]
forall (m :: * -> *) a b.
Monad m =>
(a -> m (Maybe b)) -> [a] -> m [b]
mapMaybeM ((Name -> Fixity -> SgM (Maybe DLetDec))
-> (Name, Fixity) -> SgM (Maybe DLetDec)
forall a b c. (a -> b -> c) -> (a, b) -> c
uncurry Name -> Fixity -> SgM (Maybe DLetDec)
forall (q :: * -> *).
OptionsMonad q =>
Name -> Fixity -> q (Maybe DLetDec)
singInfixDecl) ([(Name, Fixity)] -> SgM [DLetDec])
-> [(Name, Fixity)] -> SgM [DLetDec]
forall a b. (a -> b) -> a -> b
$ OMap Name Fixity -> [(Name, Fixity)]
forall k v. OMap k v -> [(k, v)]
OMap.assocs OMap Name Fixity
fixities
    [DType]
cls_cxt' <- (DType -> SgM DType) -> [DType] -> SgM [DType]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM DType -> SgM DType
singPred [DType]
cls_cxt
    DDec -> SgM DDec
forall (m :: * -> *) a. Monad m => a -> m a
return (DDec -> SgM DDec) -> DDec -> SgM DDec
forall a b. (a -> b) -> a -> b
$ [DType] -> Name -> [DTyVarBndrUnit] -> [FunDep] -> [DDec] -> DDec
DClassD [DType]
cls_cxt'
                     Name
sing_cls_name
                     [DTyVarBndrUnit]
cls_tvbs
                     [FunDep]
cls_fundeps   -- they are fine without modification
                     ((DLetDec -> DDec) -> [DLetDec] -> [DDec]
forall a b. (a -> b) -> [a] -> [b]
map DLetDec -> DDec
DLetDec ([DLetDec]
sing_sigs [DLetDec] -> [DLetDec] -> [DLetDec]
forall a. [a] -> [a] -> [a]
++ [DLetDec]
sing_meths [DLetDec] -> [DLetDec] -> [DLetDec]
forall a. [a] -> [a] -> [a]
++ [DLetDec]
fixities') [DDec] -> [DDec] -> [DDec]
forall a. [a] -> [a] -> [a]
++ [DDec]
default_sigs)
  where
    no_meth_defns :: a
no_meth_defns = String -> a
forall a. HasCallStack => String -> a
error String
"Internal error: can't find declared method type"
    always_sig :: a
always_sig    = String -> a
forall a. HasCallStack => String -> a
error String
"Internal error: no signature for default method"
    meth_names :: [Name]
meth_names    = (LetBind -> Name) -> [LetBind] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map LetBind -> Name
forall a b. (a, b) -> a
fst ([LetBind] -> [Name]) -> [LetBind] -> [Name]
forall a b. (a -> b) -> a -> b
$ OMap Name DType -> [LetBind]
forall k v. OMap k v -> [(k, v)]
OMap.assocs OMap Name DType
meth_sigs

    mk_default_sig :: Options
-> Name -> DLetDec -> (a, [Name]) -> Maybe DType -> Maybe DDec
mk_default_sig Options
opts Name
meth_name (DSigD Name
s_name DType
sty) (a, [Name])
bound_kvs (Just DType
res_ki) =
      Name -> DType -> DDec
DDefaultSigD Name
s_name (DType -> DDec) -> Maybe DType -> Maybe DDec
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Options -> Name -> DType -> (a, [Name]) -> DType -> Maybe DType
forall {a}.
Options -> Name -> DType -> (a, [Name]) -> DType -> Maybe DType
add_constraints Options
opts Name
meth_name DType
sty (a, [Name])
bound_kvs DType
res_ki
    mk_default_sig Options
_ Name
_ DLetDec
_ (a, [Name])
_ Maybe DType
_ = String -> Maybe DDec
forall a. HasCallStack => String -> a
error String
"Internal error: a singled signature isn't a signature."

    add_constraints :: Options -> Name -> DType -> (a, [Name]) -> DType -> Maybe DType
add_constraints Options
opts Name
meth_name DType
sty (a
_, [Name]
bound_kvs) DType
res_ki = do  -- Maybe monad
      ([DTyVarBndrSpec]
tvbs, [DType]
cxt, [DType]
args, DType
res) <- DType -> Maybe ([DTyVarBndrSpec], [DType], [DType], DType)
forall (m :: * -> *).
MonadFail m =>
DType -> m ([DTyVarBndrSpec], [DType], [DType], DType)
unravelVanillaDType DType
sty
      DType
prom_dflt <- Name -> OMap Name DType -> Maybe DType
forall k v. Ord k => k -> OMap k v -> Maybe v
OMap.lookup Name
meth_name OMap Name DType
IfAnn Annotated (OMap Name DType) ()
promoted_defaults

      -- Filter out explicitly bound kind variables. Otherwise, if you had
      -- the following class (#312):
      --
      --  class Foo a where
      --    bar :: a -> b -> b
      --    bar _ x = x
      --
      -- Then it would be singled to:
      --
      --  class SFoo a where
      --    sBar :: forall b (x :: a) (y :: b). Sing x -> Sing y -> Sing (sBar x y)
      --    default :: forall b (x :: a) (y :: b).
      --               (Bar b x y) ~ (BarDefault b x y) => ...
      --
      -- Which applies Bar/BarDefault to b, which shouldn't happen.
      let tvs :: [DType]
tvs = (DTyVarBndrSpec -> DType) -> [DTyVarBndrSpec] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map DTyVarBndrSpec -> DType
forall flag. DTyVarBndr flag -> DType
tvbToType ([DTyVarBndrSpec] -> [DType]) -> [DTyVarBndrSpec] -> [DType]
forall a b. (a -> b) -> a -> b
$
                (DTyVarBndrSpec -> Bool) -> [DTyVarBndrSpec] -> [DTyVarBndrSpec]
forall a. (a -> Bool) -> [a] -> [a]
filter (\DTyVarBndrSpec
tvb -> DTyVarBndrSpec -> Name
forall flag. DTyVarBndr flag -> Name
extractTvbName DTyVarBndrSpec
tvb Name -> Set Name -> Bool
forall a. Ord a => a -> Set a -> Bool
`Set.member` Set Name
bound_kv_set) [DTyVarBndrSpec]
tvbs
          prom_meth :: DType
prom_meth =  Name -> DType
DConT (Name -> DType) -> Name -> DType
forall a b. (a -> b) -> a -> b
$ Options -> Name -> Name
defunctionalizedName0 Options
opts Name
meth_name
          default_pred :: DType
default_pred = DType -> [DType] -> DType
foldType (Name -> DType
DConT Name
equalityName)
                                -- NB: Need the res_ki here to prevent ambiguous
                                -- kinds in result-inferred default methods.
                                -- See #175
                               [ DType -> [DType] -> DType
foldApply DType
prom_meth [DType]
tvs DType -> DType -> DType
`DSigT` DType
res_ki
                               , DType -> [DType] -> DType
foldApply DType
prom_dflt [DType]
tvs ]
      DType -> Maybe DType
forall (m :: * -> *) a. Monad m => a -> m a
return (DType -> Maybe DType) -> DType -> Maybe DType
forall a b. (a -> b) -> a -> b
$ [DTyVarBndrSpec] -> [DType] -> [DType] -> DType -> DType
ravelVanillaDType [DTyVarBndrSpec]
tvbs (DType
default_pred DType -> [DType] -> [DType]
forall a. a -> [a] -> [a]
: [DType]
cxt) [DType]
args DType
res
      where
        bound_kv_set :: Set Name
bound_kv_set = [Name] -> Set Name
forall a. Ord a => [a] -> Set a
Set.fromList [Name]
bound_kvs

singInstD :: AInstDecl -> SgM DDec
singInstD :: AInstDecl -> SgM DDec
singInstD (InstDecl { id_cxt :: forall (ann :: AnnotationFlag). InstDecl ann -> [DType]
id_cxt = [DType]
cxt, id_name :: forall (ann :: AnnotationFlag). InstDecl ann -> Name
id_name = Name
inst_name, id_arg_tys :: forall (ann :: AnnotationFlag). InstDecl ann -> [DType]
id_arg_tys = [DType]
inst_tys
                    , id_sigs :: forall (ann :: AnnotationFlag). InstDecl ann -> OMap Name DType
id_sigs = OMap Name DType
inst_sigs, id_meths :: forall (ann :: AnnotationFlag).
InstDecl ann -> [(Name, LetDecRHS ann)]
id_meths = [(Name, LetDecRHS Annotated)]
ann_meths }) = do
  Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  let s_inst_name :: Name
s_inst_name = Options -> Name -> Name
singledClassName Options
opts Name
inst_name
  [DType] -> SgM DDec -> SgM DDec
forall a. [DType] -> SgM a -> SgM a
bindContext [DType]
cxt (SgM DDec -> SgM DDec) -> SgM DDec -> SgM DDec
forall a b. (a -> b) -> a -> b
$ do
    [DType]
cxt' <- (DType -> SgM DType) -> [DType] -> SgM [DType]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM DType -> SgM DType
singPred [DType]
cxt
    [DType]
inst_kis <- (DType -> SgM DType) -> [DType] -> SgM [DType]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM DType -> SgM DType
forall (m :: * -> *). OptionsMonad m => DType -> m DType
promoteType [DType]
inst_tys
    [DDec]
meths <- ((Name, LetDecRHS Annotated) -> SgM [DDec])
-> [(Name, LetDecRHS Annotated)] -> SgM [DDec]
forall (monad :: * -> *) monoid (t :: * -> *) a.
(Monad monad, Monoid monoid, Traversable t) =>
(a -> monad monoid) -> t a -> monad monoid
concatMapM ((Name -> LetDecRHS Annotated -> SgM [DDec])
-> (Name, LetDecRHS Annotated) -> SgM [DDec]
forall a b c. (a -> b -> c) -> (a, b) -> c
uncurry Name -> LetDecRHS Annotated -> SgM [DDec]
sing_meth) [(Name, LetDecRHS Annotated)]
ann_meths
    DDec -> SgM DDec
forall (m :: * -> *) a. Monad m => a -> m a
return (Maybe Overlap
-> Maybe [DTyVarBndrUnit] -> [DType] -> DType -> [DDec] -> DDec
DInstanceD Maybe Overlap
forall a. Maybe a
Nothing
                       Maybe [DTyVarBndrUnit]
forall a. Maybe a
Nothing
                       [DType]
cxt'
                       ((DType -> DType -> DType) -> DType -> [DType] -> DType
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl DType -> DType -> DType
DAppT (Name -> DType
DConT Name
s_inst_name) [DType]
inst_kis)
                       [DDec]
meths)

  where
    sing_meth :: Name -> ALetDecRHS -> SgM [DDec]
    sing_meth :: Name -> LetDecRHS Annotated -> SgM [DDec]
sing_meth Name
name LetDecRHS Annotated
rhs = do
      Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
      Maybe DInfo
mb_s_info <- Name -> SgM (Maybe DInfo)
forall (q :: * -> *). DsMonad q => Name -> q (Maybe DInfo)
dsReify (Options -> Name -> Name
singledValueName Options
opts Name
name)
      [DType]
inst_kis <- (DType -> SgM DType) -> [DType] -> SgM [DType]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM DType -> SgM DType
forall (m :: * -> *). OptionsMonad m => DType -> m DType
promoteType [DType]
inst_tys
      let mk_subst :: [DTyVarBndr flag] -> Map Name DType
mk_subst [DTyVarBndr flag]
cls_tvbs = [LetBind] -> Map Name DType
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList ([LetBind] -> Map Name DType) -> [LetBind] -> Map Name DType
forall a b. (a -> b) -> a -> b
$ [Name] -> [DType] -> [LetBind]
forall a b. [a] -> [b] -> [(a, b)]
zip ((DTyVarBndr flag -> Name) -> [DTyVarBndr flag] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map DTyVarBndr flag -> Name
forall flag. DTyVarBndr flag -> Name
extractTvbName [DTyVarBndr flag]
vis_cls_tvbs) [DType]
inst_kis
            where
              -- This is a half-hearted attempt to address the underlying problem
              -- in #358, where we can sometimes have more class type variables
              -- (due to implicit kind arguments) than class arguments. This just
              -- ensures that the explicit type variables are properly mapped
              -- to the class arguments, leaving the implicit kind variables
              -- unmapped. That could potentially cause *other* problems, but
              -- those are perhaps best avoided by using InstanceSigs. At the
              -- very least, this workaround will make error messages slightly
              -- less confusing.
              vis_cls_tvbs :: [DTyVarBndr flag]
vis_cls_tvbs = Int -> [DTyVarBndr flag] -> [DTyVarBndr flag]
forall a. Int -> [a] -> [a]
drop ([DTyVarBndr flag] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [DTyVarBndr flag]
cls_tvbs Int -> Int -> Int
forall a. Num a => a -> a -> a
- [DType] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [DType]
inst_kis) [DTyVarBndr flag]
cls_tvbs

          sing_meth_ty :: OSet Name -> DType
                       -> SgM (DType, [Name], DCxt, DKind)
          sing_meth_ty :: OSet Name -> DType -> SgM (DType, [Name], [DType], DType)
sing_meth_ty OSet Name
bound_kvs DType
inner_ty = do
            -- Make sure to expand through type synonyms here! Not doing so
            -- resulted in #167.
            DType
raw_ty <- DType -> SgM DType
forall (q :: * -> *) a. (DsMonad q, Data a) => a -> q a
expand DType
inner_ty
            (DType
s_ty, Int
_num_args, [Name]
tyvar_names, [DType]
ctxt, [DType]
_arg_kis, DType
res_ki)
              <- OSet Name
-> DType
-> DType
-> SgM (DType, Int, [Name], [DType], [DType], DType)
singType OSet Name
bound_kvs (Name -> DType
DConT (Name -> DType) -> Name -> DType
forall a b. (a -> b) -> a -> b
$ Options -> Name -> Name
defunctionalizedName0 Options
opts Name
name) DType
raw_ty
            (DType, [Name], [DType], DType)
-> SgM (DType, [Name], [DType], DType)
forall (f :: * -> *) a. Applicative f => a -> f a
pure (DType
s_ty, [Name]
tyvar_names, [DType]
ctxt, DType
res_ki)

      (DType
s_ty, [Name]
tyvar_names, [DType]
ctxt, Maybe DType
m_res_ki) <- case Name -> OMap Name DType -> Maybe DType
forall k v. Ord k => k -> OMap k v -> Maybe v
OMap.lookup Name
name OMap Name DType
inst_sigs of
        Just DType
inst_sig -> do
          -- We have an InstanceSig, so just single that type. Take care to
          -- avoid binding the variables bound by the instance head as well.
          let inst_bound :: OSet Name
inst_bound = (DType -> OSet Name) -> [DType] -> OSet Name
forall (t :: * -> *) m a.
(Foldable t, Monoid m) =>
(a -> m) -> t a -> m
foldMap DType -> OSet Name
fvDType ([DType]
cxt [DType] -> [DType] -> [DType]
forall a. [a] -> [a] -> [a]
++ [DType]
inst_kis)
          (DType
s_ty, [Name]
tyvar_names, [DType]
ctxt, DType
res_ki) <- OSet Name -> DType -> SgM (DType, [Name], [DType], DType)
sing_meth_ty OSet Name
inst_bound DType
inst_sig
          (DType, [Name], [DType], Maybe DType)
-> SgM (DType, [Name], [DType], Maybe DType)
forall (f :: * -> *) a. Applicative f => a -> f a
pure (DType
s_ty, [Name]
tyvar_names, [DType]
ctxt, DType -> Maybe DType
forall a. a -> Maybe a
Just DType
res_ki)
        Maybe DType
Nothing -> case Maybe DInfo
mb_s_info of
          -- We don't have an InstanceSig, so we must compute the type to use
          -- in the singled instance ourselves through reification.
          Just (DVarI Name
_ (DForallT (DForallInvis [DTyVarBndrSpec]
cls_tvbs) (DConstrainedT [DType]
_cls_pred DType
s_ty)) Maybe Name
_) -> do
            ([DTyVarBndrSpec]
sing_tvbs, [DType]
ctxt, [DType]
_args, DType
res_ty) <- DType -> SgM ([DTyVarBndrSpec], [DType], [DType], DType)
forall (m :: * -> *).
MonadFail m =>
DType -> m ([DTyVarBndrSpec], [DType], [DType], DType)
unravelVanillaDType DType
s_ty
            let subst :: Map Name DType
subst = [DTyVarBndrSpec] -> Map Name DType
forall {flag}. [DTyVarBndr flag] -> Map Name DType
mk_subst [DTyVarBndrSpec]
cls_tvbs
                m_res_ki :: Maybe DType
m_res_ki = case DType
res_ty of
                  DType
_sing `DAppT` (DType
_prom_func `DSigT` DType
res_ki) -> DType -> Maybe DType
forall a. a -> Maybe a
Just (Map Name DType -> DType -> DType
substKind Map Name DType
subst DType
res_ki)
                  DType
_                                         -> Maybe DType
forall a. Maybe a
Nothing

            (DType, [Name], [DType], Maybe DType)
-> SgM (DType, [Name], [DType], Maybe DType)
forall (f :: * -> *) a. Applicative f => a -> f a
pure ( Map Name DType -> DType -> DType
substType Map Name DType
subst DType
s_ty
                 , (DTyVarBndrSpec -> Name) -> [DTyVarBndrSpec] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map DTyVarBndrSpec -> Name
forall flag. DTyVarBndr flag -> Name
extractTvbName [DTyVarBndrSpec]
sing_tvbs
                 , (DType -> DType) -> [DType] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map (Map Name DType -> DType -> DType
substType Map Name DType
subst) [DType]
ctxt
                 , Maybe DType
m_res_ki )
          Maybe DInfo
_ -> do
            Maybe DInfo
mb_info <- Name -> SgM (Maybe DInfo)
forall (q :: * -> *). DsMonad q => Name -> q (Maybe DInfo)
dsReify Name
name
            case Maybe DInfo
mb_info of
              Just (DVarI Name
_ (DForallT (DForallInvis [DTyVarBndrSpec]
cls_tvbs)
                                      (DConstrainedT [DType]
_cls_pred DType
inner_ty)) Maybe Name
_) -> do
                let subst :: Map Name DType
subst = [DTyVarBndrSpec] -> Map Name DType
forall {flag}. [DTyVarBndr flag] -> Map Name DType
mk_subst [DTyVarBndrSpec]
cls_tvbs
                    cls_kvb_names :: OSet Name
cls_kvb_names = (DTyVarBndrSpec -> OSet Name) -> [DTyVarBndrSpec] -> OSet Name
forall (t :: * -> *) m a.
(Foldable t, Monoid m) =>
(a -> m) -> t a -> m
foldMap ((DType -> OSet Name) -> Maybe DType -> OSet Name
forall (t :: * -> *) m a.
(Foldable t, Monoid m) =>
(a -> m) -> t a -> m
foldMap DType -> OSet Name
fvDType (Maybe DType -> OSet Name)
-> (DTyVarBndrSpec -> Maybe DType) -> DTyVarBndrSpec -> OSet Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. DTyVarBndrSpec -> Maybe DType
forall flag. DTyVarBndr flag -> Maybe DType
extractTvbKind) [DTyVarBndrSpec]
cls_tvbs
                    cls_tvb_names :: OSet Name
cls_tvb_names = [Name] -> OSet Name
forall a. Ord a => [a] -> OSet a
OSet.fromList ([Name] -> OSet Name) -> [Name] -> OSet Name
forall a b. (a -> b) -> a -> b
$ (DTyVarBndrSpec -> Name) -> [DTyVarBndrSpec] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map DTyVarBndrSpec -> Name
forall flag. DTyVarBndr flag -> Name
extractTvbName [DTyVarBndrSpec]
cls_tvbs
                    cls_bound :: OSet Name
cls_bound     = OSet Name
cls_kvb_names OSet Name -> OSet Name -> OSet Name
forall a. Ord a => OSet a -> OSet a -> OSet a
`OSet.union` OSet Name
cls_tvb_names
                (DType
s_ty, [Name]
tyvar_names, [DType]
ctxt, DType
res_ki) <- OSet Name -> DType -> SgM (DType, [Name], [DType], DType)
sing_meth_ty OSet Name
cls_bound DType
inner_ty
                (DType, [Name], [DType], Maybe DType)
-> SgM (DType, [Name], [DType], Maybe DType)
forall (f :: * -> *) a. Applicative f => a -> f a
pure ( Map Name DType -> DType -> DType
substType Map Name DType
subst DType
s_ty
                     , [Name]
tyvar_names
                     , [DType]
ctxt
                     , DType -> Maybe DType
forall a. a -> Maybe a
Just (Map Name DType -> DType -> DType
substKind Map Name DType
subst DType
res_ki) )
              Maybe DInfo
_ -> String -> SgM (DType, [Name], [DType], Maybe DType)
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String -> SgM (DType, [Name], [DType], Maybe DType))
-> String -> SgM (DType, [Name], [DType], Maybe DType)
forall a b. (a -> b) -> a -> b
$ String
"Cannot find type of method " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Name -> String
forall a. Show a => a -> String
show Name
name

      let kind_map :: Map Name DType
kind_map = Map Name DType
-> (DType -> Map Name DType) -> Maybe DType -> Map Name DType
forall b a. b -> (a -> b) -> Maybe a -> b
maybe Map Name DType
forall k a. Map k a
Map.empty (Name -> DType -> Map Name DType
forall k a. k -> a -> Map k a
Map.singleton Name
name) Maybe DType
m_res_ki
      DLetDec
meth' <- Map Name [Name]
-> Map Name [DType]
-> Map Name DType
-> Name
-> LetDecRHS Annotated
-> SgM DLetDec
singLetDecRHS (Name -> [Name] -> Map Name [Name]
forall k a. k -> a -> Map k a
Map.singleton Name
name [Name]
tyvar_names)
                             (Name -> [DType] -> Map Name [DType]
forall k a. k -> a -> Map k a
Map.singleton Name
name [DType]
ctxt)
                             Map Name DType
kind_map Name
name LetDecRHS Annotated
rhs
      [DDec] -> SgM [DDec]
forall (m :: * -> *) a. Monad m => a -> m a
return ([DDec] -> SgM [DDec]) -> [DDec] -> SgM [DDec]
forall a b. (a -> b) -> a -> b
$ (DLetDec -> DDec) -> [DLetDec] -> [DDec]
forall a b. (a -> b) -> [a] -> [b]
map DLetDec -> DDec
DLetDec [Name -> DType -> DLetDec
DSigD (Options -> Name -> Name
singledValueName Options
opts Name
name) DType
s_ty, DLetDec
meth']

singLetDecEnv :: ALetDecEnv
              -> SgM a
              -> SgM ([DLetDec], [DDec], a)
                 -- Return:
                 --
                 -- 1. The singled let-decs
                 -- 2. SingI instances for any defunctionalization symbols
                 --    (see Data.Singletons.TH.Single.Defun)
                 -- 3. The result of running the `SgM a` action
singLetDecEnv :: forall a. ALetDecEnv -> SgM a -> SgM ([DLetDec], [DDec], a)
singLetDecEnv (LetDecEnv { lde_defns :: forall (ann :: AnnotationFlag).
LetDecEnv ann -> OMap Name (LetDecRHS ann)
lde_defns     = OMap Name (LetDecRHS Annotated)
defns
                         , lde_types :: forall (ann :: AnnotationFlag). LetDecEnv ann -> OMap Name DType
lde_types     = OMap Name DType
types
                         , lde_infix :: forall (ann :: AnnotationFlag). LetDecEnv ann -> OMap Name Fixity
lde_infix     = OMap Name Fixity
infix_decls
                         , lde_proms :: forall (ann :: AnnotationFlag).
LetDecEnv ann -> IfAnn ann (OMap Name DType) ()
lde_proms     = IfAnn Annotated (OMap Name DType) ()
proms
                         , lde_bound_kvs :: forall (ann :: AnnotationFlag).
LetDecEnv ann -> IfAnn ann (OMap Name (OSet Name)) ()
lde_bound_kvs = IfAnn Annotated (OMap Name (OSet Name)) ()
bound_kvs })
              SgM a
thing_inside = do
  let prom_list :: [LetBind]
prom_list = OMap Name DType -> [LetBind]
forall k v. OMap k v -> [(k, v)]
OMap.assocs OMap Name DType
IfAnn Annotated (OMap Name DType) ()
proms
  ([DLetDec]
typeSigs, [(Name, DExp)]
letBinds, [(Name, [Name])]
tyvarNames, [(Name, [DType])]
cxts, [Maybe DType]
res_kis, [[DDec]]
singIDefunss)
    <- [(DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
  Maybe DType, [DDec])]
-> ([DLetDec], [(Name, DExp)], [(Name, [Name])], [(Name, [DType])],
    [Maybe DType], [[DDec]])
forall a b c d e f.
[(a, b, c, d, e, f)] -> ([a], [b], [c], [d], [e], [f])
unzip6 ([(DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
   Maybe DType, [DDec])]
 -> ([DLetDec], [(Name, DExp)], [(Name, [Name])], [(Name, [DType])],
     [Maybe DType], [[DDec]]))
-> SgM
     [(DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
       Maybe DType, [DDec])]
-> SgM
     ([DLetDec], [(Name, DExp)], [(Name, [Name])], [(Name, [DType])],
      [Maybe DType], [[DDec]])
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (LetBind
 -> SgM
      (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
       Maybe DType, [DDec]))
-> [LetBind]
-> SgM
     [(DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
       Maybe DType, [DDec])]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((Name
 -> DType
 -> SgM
      (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
       Maybe DType, [DDec]))
-> LetBind
-> SgM
     (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
      Maybe DType, [DDec])
forall a b c. (a -> b -> c) -> (a, b) -> c
uncurry (OMap Name (LetDecRHS Annotated)
-> OMap Name DType
-> OMap Name (OSet Name)
-> Name
-> DType
-> SgM
     (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
      Maybe DType, [DDec])
singTySig OMap Name (LetDecRHS Annotated)
defns OMap Name DType
types OMap Name (OSet Name)
IfAnn Annotated (OMap Name (OSet Name)) ()
bound_kvs)) [LetBind]
prom_list
  [DLetDec]
infix_decls' <- ((Name, Fixity) -> SgM (Maybe DLetDec))
-> [(Name, Fixity)] -> SgM [DLetDec]
forall (m :: * -> *) a b.
Monad m =>
(a -> m (Maybe b)) -> [a] -> m [b]
mapMaybeM ((Name -> Fixity -> SgM (Maybe DLetDec))
-> (Name, Fixity) -> SgM (Maybe DLetDec)
forall a b c. (a -> b -> c) -> (a, b) -> c
uncurry Name -> Fixity -> SgM (Maybe DLetDec)
forall (q :: * -> *).
OptionsMonad q =>
Name -> Fixity -> q (Maybe DLetDec)
singInfixDecl) ([(Name, Fixity)] -> SgM [DLetDec])
-> [(Name, Fixity)] -> SgM [DLetDec]
forall a b. (a -> b) -> a -> b
$ OMap Name Fixity -> [(Name, Fixity)]
forall k v. OMap k v -> [(k, v)]
OMap.assocs OMap Name Fixity
infix_decls
  let res_ki_map :: Map Name DType
res_ki_map = [LetBind] -> Map Name DType
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList [ (Name
name, DType
res_ki) | ((Name
name, DType
_), Just DType
res_ki)
                                                     <- [LetBind] -> [Maybe DType] -> [(LetBind, Maybe DType)]
forall a b. [a] -> [b] -> [(a, b)]
zip [LetBind]
prom_list [Maybe DType]
res_kis ]
  [(Name, DExp)]
-> SgM ([DLetDec], [DDec], a) -> SgM ([DLetDec], [DDec], a)
forall a. [(Name, DExp)] -> SgM a -> SgM a
bindLets [(Name, DExp)]
letBinds (SgM ([DLetDec], [DDec], a) -> SgM ([DLetDec], [DDec], a))
-> SgM ([DLetDec], [DDec], a) -> SgM ([DLetDec], [DDec], a)
forall a b. (a -> b) -> a -> b
$ do
    [DLetDec]
let_decs <- ((Name, LetDecRHS Annotated) -> SgM DLetDec)
-> [(Name, LetDecRHS Annotated)] -> SgM [DLetDec]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((Name -> LetDecRHS Annotated -> SgM DLetDec)
-> (Name, LetDecRHS Annotated) -> SgM DLetDec
forall a b c. (a -> b -> c) -> (a, b) -> c
uncurry (Map Name [Name]
-> Map Name [DType]
-> Map Name DType
-> Name
-> LetDecRHS Annotated
-> SgM DLetDec
singLetDecRHS ([(Name, [Name])] -> Map Name [Name]
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList [(Name, [Name])]
tyvarNames)
                                             ([(Name, [DType])] -> Map Name [DType]
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList [(Name, [DType])]
cxts)
                                             Map Name DType
res_ki_map))
                     (OMap Name (LetDecRHS Annotated) -> [(Name, LetDecRHS Annotated)]
forall k v. OMap k v -> [(k, v)]
OMap.assocs OMap Name (LetDecRHS Annotated)
defns)
    a
thing <- SgM a
thing_inside
    ([DLetDec], [DDec], a) -> SgM ([DLetDec], [DDec], a)
forall (m :: * -> *) a. Monad m => a -> m a
return ([DLetDec]
infix_decls' [DLetDec] -> [DLetDec] -> [DLetDec]
forall a. [a] -> [a] -> [a]
++ [DLetDec]
typeSigs [DLetDec] -> [DLetDec] -> [DLetDec]
forall a. [a] -> [a] -> [a]
++ [DLetDec]
let_decs, [[DDec]] -> [DDec]
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [[DDec]]
singIDefunss, a
thing)

singTySig :: OMap Name ALetDecRHS  -- definitions
          -> OMap Name DType       -- type signatures
          -> OMap Name (OSet Name) -- bound kind variables
          -> Name -> DType   -- the type is the promoted type, not the type sig!
          -> SgM ( DLetDec               -- the new type signature
                 , (Name, DExp)          -- the let-bind entry
                 , (Name, [Name])        -- the scoped tyvar names in the tysig
                 , (Name, DCxt)          -- the context of the type signature
                 , Maybe DKind           -- the result kind in the tysig
                 , [DDec]                -- SingI instances for defun symbols
                 )
singTySig :: OMap Name (LetDecRHS Annotated)
-> OMap Name DType
-> OMap Name (OSet Name)
-> Name
-> DType
-> SgM
     (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
      Maybe DType, [DDec])
singTySig OMap Name (LetDecRHS Annotated)
defns OMap Name DType
types OMap Name (OSet Name)
bound_kvs Name
name DType
prom_ty = do
  Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  let sName :: Name
sName = Options -> Name -> Name
singledValueName Options
opts Name
name
  case Name -> OMap Name DType -> Maybe DType
forall k v. Ord k => k -> OMap k v -> Maybe v
OMap.lookup Name
name OMap Name DType
types of
    Maybe DType
Nothing -> do
      Int
num_args <- SgM Int
guess_num_args
      (DType
sty, [Name]
tyvar_names) <- Int -> SgM (DType, [Name])
mk_sing_ty Int
num_args
      [DDec]
singIDefuns <- Name
-> NameSpace
-> [DType]
-> [Maybe DType]
-> Maybe DType
-> SgM [DDec]
singDefuns Name
name NameSpace
VarName []
                                ((Name -> Maybe DType) -> [Name] -> [Maybe DType]
forall a b. (a -> b) -> [a] -> [b]
map (Maybe DType -> Name -> Maybe DType
forall a b. a -> b -> a
const Maybe DType
forall a. Maybe a
Nothing) [Name]
tyvar_names) Maybe DType
forall a. Maybe a
Nothing
      (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
 Maybe DType, [DDec])
-> SgM
     (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
      Maybe DType, [DDec])
forall (m :: * -> *) a. Monad m => a -> m a
return ( Name -> DType -> DLetDec
DSigD Name
sName DType
sty
             , (Name
name, Int -> DType -> DExp -> DExp
wrapSingFun Int
num_args DType
prom_ty (Name -> DExp
DVarE Name
sName))
             , (Name
name, [Name]
tyvar_names)
             , (Name
name, [])
             , Maybe DType
forall a. Maybe a
Nothing
             , [DDec]
singIDefuns )
    Just DType
ty -> do
      OSet Name
all_bound_kvs <- SgM (OSet Name)
lookup_bound_kvs
      (DType
sty, Int
num_args, [Name]
tyvar_names, [DType]
ctxt, [DType]
arg_kis, DType
res_ki)
        <- OSet Name
-> DType
-> DType
-> SgM (DType, Int, [Name], [DType], [DType], DType)
singType OSet Name
all_bound_kvs DType
prom_ty DType
ty
      [DType]
bound_cxt <- SgM [DType]
askContext
      [DDec]
singIDefuns <- Name
-> NameSpace
-> [DType]
-> [Maybe DType]
-> Maybe DType
-> SgM [DDec]
singDefuns Name
name NameSpace
VarName ([DType]
bound_cxt [DType] -> [DType] -> [DType]
forall a. [a] -> [a] -> [a]
++ [DType]
ctxt)
                                ((DType -> Maybe DType) -> [DType] -> [Maybe DType]
forall a b. (a -> b) -> [a] -> [b]
map DType -> Maybe DType
forall a. a -> Maybe a
Just [DType]
arg_kis) (DType -> Maybe DType
forall a. a -> Maybe a
Just DType
res_ki)
      (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
 Maybe DType, [DDec])
-> SgM
     (DLetDec, (Name, DExp), (Name, [Name]), (Name, [DType]),
      Maybe DType, [DDec])
forall (m :: * -> *) a. Monad m => a -> m a
return ( Name -> DType -> DLetDec
DSigD Name
sName DType
sty
             , (Name
name, Int -> DType -> DExp -> DExp
wrapSingFun Int
num_args DType
prom_ty (Name -> DExp
DVarE Name
sName))
             , (Name
name, [Name]
tyvar_names)
             , (Name
name, [DType]
ctxt)
             , DType -> Maybe DType
forall a. a -> Maybe a
Just DType
res_ki
             , [DDec]
singIDefuns )
  where
    guess_num_args :: SgM Int
    guess_num_args :: SgM Int
guess_num_args =
      case Name
-> OMap Name (LetDecRHS Annotated) -> Maybe (LetDecRHS Annotated)
forall k v. Ord k => k -> OMap k v -> Maybe v
OMap.lookup Name
name OMap Name (LetDecRHS Annotated)
defns of
        Maybe (LetDecRHS Annotated)
Nothing -> String -> SgM Int
forall (m :: * -> *) a. MonadFail m => String -> m a
fail String
"Internal error: promotion known for something not let-bound."
        Just (AValue DType
_ Int
n ADExp
_) -> Int -> SgM Int
forall (m :: * -> *) a. Monad m => a -> m a
return Int
n
        Just (AFunction DType
_ Int
n [ADClause]
_) -> Int -> SgM Int
forall (m :: * -> *) a. Monad m => a -> m a
return Int
n

    lookup_bound_kvs :: SgM (OSet Name)
    lookup_bound_kvs :: SgM (OSet Name)
lookup_bound_kvs =
      case Name -> OMap Name (OSet Name) -> Maybe (OSet Name)
forall k v. Ord k => k -> OMap k v -> Maybe v
OMap.lookup Name
name OMap Name (OSet Name)
bound_kvs of
        Maybe (OSet Name)
Nothing -> String -> SgM (OSet Name)
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String -> SgM (OSet Name)) -> String -> SgM (OSet Name)
forall a b. (a -> b) -> a -> b
$ String
"Internal error: " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Name -> String
nameBase Name
name String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
" has no type variable "
                          String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
"bindings, despite having a type signature"
        Just OSet Name
kvs -> OSet Name -> SgM (OSet Name)
forall (f :: * -> *) a. Applicative f => a -> f a
pure OSet Name
kvs

      -- create a Sing t1 -> Sing t2 -> ... type of a given arity and result type
    mk_sing_ty :: Int -> SgM (DType, [Name])
    mk_sing_ty :: Int -> SgM (DType, [Name])
mk_sing_ty Int
n = do
      [Name]
arg_names <- Int -> SgM Name -> SgM [Name]
forall (m :: * -> *) a. Applicative m => Int -> m a -> m [a]
replicateM Int
n (String -> SgM Name
forall (m :: * -> *). Quasi m => String -> m Name
qNewName String
"arg")
      -- If there are no arguments, use `Sing @_` instead of `Sing`.
      -- See Note [Disable kind generalization for local functions if possible]
      let sing_w_wildcard :: DType
sing_w_wildcard | Int
n Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0    = DType
singFamily DType -> DType -> DType
`DAppKindT` DType
DWildCardT
                          | Bool
otherwise = DType
singFamily
      (DType, [Name]) -> SgM (DType, [Name])
forall (m :: * -> *) a. Monad m => a -> m a
return ( [DTyVarBndrSpec] -> [DType] -> [DType] -> DType -> DType
ravelVanillaDType
                 ((Name -> DTyVarBndrSpec) -> [Name] -> [DTyVarBndrSpec]
forall a b. (a -> b) -> [a] -> [b]
map (Name -> Specificity -> DTyVarBndrSpec
forall flag. Name -> flag -> DTyVarBndr flag
`DPlainTV` Specificity
SpecifiedSpec) [Name]
arg_names)
                 []
                 ((Name -> DType) -> [Name] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map (\Name
nm -> DType
singFamily DType -> DType -> DType
`DAppT` Name -> DType
DVarT Name
nm) [Name]
arg_names)
                 (DType
sing_w_wildcard DType -> DType -> DType
`DAppT`
                      ((DType -> DType -> DType) -> DType -> [DType] -> DType
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl DType -> DType -> DType
apply DType
prom_ty ((Name -> DType) -> [Name] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map Name -> DType
DVarT [Name]
arg_names)))
             , [Name]
arg_names )

{-
Note [Disable kind generalization for local functions if possible]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider this example (from #296):

  f :: forall a. MyProxy a -> MyProxy a
  f MyProxy =
    let x = let z :: MyProxy a
                z = MyProxy in z
    in x

A naïve attempt at singling `f` is as follows:

  type LetZ :: MyProxy a
  type family LetZ where
    LetZ = 'MyProxy

  type family LetX where
    LetX = LetZ

  type F :: forall a. MyProxy a -> MyProxy a
  type family F x where
    F 'MyProxy = LetX

  sF :: forall a (t :: MyProxy a). Sing t -> Sing (F t :: MyProxy a)
  sF SMyProxy =
    let sX :: Sing LetX
        sX = let sZ :: Sing (LetZ :: MyProxy a)
                 sZ = SMyProxy in sZ
    in sX

This will not typecheck, however. The is because the return kind of
`LetX` (in `let sX :: Sing LetX`) will get generalized by virtue of `sX`
having a type signature. It's as if one had written this:

  sF :: forall a (t :: MyProxy a). Sing t -> Sing (F t :: MyProxy a)
  sF SMyProxy =
    let sX :: forall a1. Sing (LetX :: MyProxy a1)
        sX = ...

This is too general, since `sX` will only typecheck if the return kind of
`LetX` is `MyProxy a`, not `MyProxy a1`. In order to avoid this problem,
we need to avoid kind generalization when kind-checking the type of `sX`.
To accomplish this, we borrow a trick from
Note [The id hack; or, how singletons-th learned to stop worrying and avoid kind generalization]
and use TypeApplications plus a wildcard type. That is, we generate this code
for `sF`:

  sF :: forall a (t :: MyProxy a). Sing t -> Sing (F t :: MyProxy a)
  sF SMyProxy =
    let sX :: Sing @_ LetX
        sX = ...

The presence of the wildcard type disables kind generalization, which allows
GHC's kind inference to deduce that the return kind of `LetX` should be `a`.
Now `sF` typechecks, and since we only use wildcards within visible kind
applications, we don't even have to force users to enable
PartialTypeSignatures. Hooray!

Question: where should we put wildcard types when singling? One possible answer
is: put a wildcard in any type signature that gets generated when singling a
function that lacks a type signature. Unfortunately, this is a step too far.
This will break singling the `foldr` function:

    foldr                   :: (a -> b -> b) -> b -> [a] -> b
    foldr k z = go
              where
                go []     = z
                go (y:ys) = y `k` go ys

If the type of `sGo` is given a wildcard, then it will fail to typecheck. This
is because `sGo` is polymorphically recursive, so disabling kind generalization
forces GHC to infer `sGo`'s type. Attempting to infer a polymorphically
recursive type, unsurprisingly, leads to failure.

To avoid this sort of situation, where adopt a simple metric: if a function
lacks a type signature, only put @_ in its singled type signature if it has
zero arguments. This allows `sX` to typecheck without breaking things like
`sGo`. This metric is a bit conservative, however, since it means that this
small tweak to `x` still would not typecheck:

  f :: forall a. MyProxy a -> MyProxy a
  f MyProxy =
    let x () = let z :: MyProxy a
                   z = MyProxy in z
    in x ()

We need not let perfect be the enemy of good, however. It is extremely
common for local definitions to have zero arguments, so it makes good sense
to optimize for that special case. In fact, this special treatment is the only
reason that `foo8` from the `T183` test case singles successfully, since
the as-patterns in `foo8` desugar to code very similar to the `f` example
above.
-}

singLetDecRHS :: Map Name [Name]
              -> Map Name DCxt    -- the context of the type signature
                                  -- (might not be known)
              -> Map Name DKind   -- result kind (might not be known)
              -> Name -> ALetDecRHS -> SgM DLetDec
singLetDecRHS :: Map Name [Name]
-> Map Name [DType]
-> Map Name DType
-> Name
-> LetDecRHS Annotated
-> SgM DLetDec
singLetDecRHS Map Name [Name]
bound_names Map Name [DType]
cxts Map Name DType
res_kis Name
name LetDecRHS Annotated
ld_rhs = do
  Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  [DType] -> SgM DLetDec -> SgM DLetDec
forall a. [DType] -> SgM a -> SgM a
bindContext ([DType] -> Name -> Map Name [DType] -> [DType]
forall k a. Ord k => a -> k -> Map k a -> a
Map.findWithDefault [] Name
name Map Name [DType]
cxts) (SgM DLetDec -> SgM DLetDec) -> SgM DLetDec -> SgM DLetDec
forall a b. (a -> b) -> a -> b
$
    case LetDecRHS Annotated
ld_rhs of
      AValue DType
prom Int
num_arrows ADExp
exp ->
        DPat -> DExp -> DLetDec
DValD (Name -> DPat
DVarP (Options -> Name -> Name
singledValueName Options
opts Name
name)) (DExp -> DLetDec) -> SgM DExp -> SgM DLetDec
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$>
        (Int -> DType -> DExp -> DExp
wrapUnSingFun Int
num_arrows DType
prom (DExp -> DExp) -> SgM DExp -> SgM DExp
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> ADExp -> Maybe DType -> SgM DExp
singExp ADExp
exp (Name -> Map Name DType -> Maybe DType
forall k a. Ord k => k -> Map k a -> Maybe a
Map.lookup Name
name Map Name DType
res_kis))
      AFunction DType
prom_fun Int
num_arrows [ADClause]
clauses ->
        let tyvar_names :: [Name]
tyvar_names = case Name -> Map Name [Name] -> Maybe [Name]
forall k a. Ord k => k -> Map k a -> Maybe a
Map.lookup Name
name Map Name [Name]
bound_names of
                            Maybe [Name]
Nothing -> []
                            Just [Name]
ns -> [Name]
ns
            res_ki :: Maybe DType
res_ki = Name -> Map Name DType -> Maybe DType
forall k a. Ord k => k -> Map k a -> Maybe a
Map.lookup Name
name Map Name DType
res_kis
        in
        Name -> [DClause] -> DLetDec
DFunD (Options -> Name -> Name
singledValueName Options
opts Name
name) ([DClause] -> DLetDec) -> SgM [DClause] -> SgM DLetDec
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$>
              (ADClause -> SgM DClause) -> [ADClause] -> SgM [DClause]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (DType -> Int -> [Name] -> Maybe DType -> ADClause -> SgM DClause
singClause DType
prom_fun Int
num_arrows [Name]
tyvar_names Maybe DType
res_ki) [ADClause]
clauses

singClause :: DType   -- the promoted function
           -> Int     -- the number of arrows in the type. If this is more
                      -- than the number of patterns, we need to eta-expand
                      -- with unSingFun.
           -> [Name]  -- the names of the forall'd vars in the type sig of this
                      -- function. This list should have at least the length as the
                      -- number of patterns in the clause
           -> Maybe DKind   -- result kind, if known
           -> ADClause -> SgM DClause
singClause :: DType -> Int -> [Name] -> Maybe DType -> ADClause -> SgM DClause
singClause DType
prom_fun Int
num_arrows [Name]
bound_names Maybe DType
res_ki
           (ADClause VarPromotions
var_proms [ADPat]
pats ADExp
exp) = do

  -- Fix #166:
  Bool -> SgM () -> SgM ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Int
num_arrows Int -> Int -> Int
forall a. Num a => a -> a -> a
- [ADPat] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [ADPat]
pats Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< Int
0) (SgM () -> SgM ()) -> SgM () -> SgM ()
forall a b. (a -> b) -> a -> b
$
    String -> SgM ()
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String -> SgM ()) -> String -> SgM ()
forall a b. (a -> b) -> a -> b
$ String
"Function being promoted to " String -> String -> String
forall a. [a] -> [a] -> [a]
++ (Type -> String
forall a. Ppr a => a -> String
pprint (DType -> Type
typeToTH DType
prom_fun)) String -> String -> String
forall a. [a] -> [a] -> [a]
++
           String
" has too many arguments."

  ([DPat]
sPats, SingDSigPaInfos
sigPaExpsSigs) <- QWithAux SingDSigPaInfos SgM [DPat]
-> SgM ([DPat], SingDSigPaInfos)
forall m (q :: * -> *) a. QWithAux m q a -> q (a, m)
evalForPair (QWithAux SingDSigPaInfos SgM [DPat]
 -> SgM ([DPat], SingDSigPaInfos))
-> QWithAux SingDSigPaInfos SgM [DPat]
-> SgM ([DPat], SingDSigPaInfos)
forall a b. (a -> b) -> a -> b
$ (ADPat -> QWithAux SingDSigPaInfos SgM DPat)
-> [ADPat] -> QWithAux SingDSigPaInfos SgM [DPat]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Map Name Name -> ADPat -> QWithAux SingDSigPaInfos SgM DPat
singPat (VarPromotions -> Map Name Name
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList VarPromotions
var_proms)) [ADPat]
pats
  DExp
sBody <- ADExp -> Maybe DType -> SgM DExp
singExp ADExp
exp Maybe DType
res_ki
    -- when calling unSingFun, the promoted pats aren't in scope, so we use the
    -- bound_names instead
  let pattern_bound_names :: [Name]
pattern_bound_names = (Name -> ADPat -> Name) -> [Name] -> [ADPat] -> [Name]
forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
zipWith Name -> ADPat -> Name
forall a b. a -> b -> a
const [Name]
bound_names [ADPat]
pats
       -- this does eta-expansion. See comment at top of file.
      sBody' :: DExp
sBody' = Int -> DType -> DExp -> DExp
wrapUnSingFun (Int
num_arrows Int -> Int -> Int
forall a. Num a => a -> a -> a
- [ADPat] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [ADPat]
pats)
                 ((DType -> DType -> DType) -> DType -> [DType] -> DType
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl DType -> DType -> DType
apply DType
prom_fun ((Name -> DType) -> [Name] -> [DType]
forall a b. (a -> b) -> [a] -> [b]
map Name -> DType
DVarT [Name]
pattern_bound_names)) DExp
sBody
  DClause -> SgM DClause
forall (m :: * -> *) a. Monad m => a -> m a
return (DClause -> SgM DClause) -> DClause -> SgM DClause
forall a b. (a -> b) -> a -> b
$ [DPat] -> DExp -> DClause
DClause [DPat]
sPats (DExp -> DClause) -> DExp -> DClause
forall a b. (a -> b) -> a -> b
$ SingDSigPaInfos -> DExp -> DExp
mkSigPaCaseE SingDSigPaInfos
sigPaExpsSigs DExp
sBody'

singPat :: Map Name Name   -- from term-level names to type-level names
        -> ADPat
        -> QWithAux SingDSigPaInfos SgM DPat
singPat :: Map Name Name -> ADPat -> QWithAux SingDSigPaInfos SgM DPat
singPat Map Name Name
var_proms = ADPat -> QWithAux SingDSigPaInfos SgM DPat
go
  where
    go :: ADPat -> QWithAux SingDSigPaInfos SgM DPat
    go :: ADPat -> QWithAux SingDSigPaInfos SgM DPat
go (ADLitP Lit
_lit) =
      String -> QWithAux SingDSigPaInfos SgM DPat
forall (m :: * -> *) a. MonadFail m => String -> m a
fail String
"Singling of literal patterns not yet supported"
    go (ADVarP Name
name) = do
      Options
opts <- QWithAux SingDSigPaInfos SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
      Name
tyname <- case Name -> Map Name Name -> Maybe Name
forall k a. Ord k => k -> Map k a -> Maybe a
Map.lookup Name
name Map Name Name
var_proms of
                  Maybe Name
Nothing     ->
                    String -> QWithAux SingDSigPaInfos SgM Name
forall (m :: * -> *) a. MonadFail m => String -> m a
fail String
"Internal error: unknown variable when singling pattern"
                  Just Name
tyname -> Name -> QWithAux SingDSigPaInfos SgM Name
forall (m :: * -> *) a. Monad m => a -> m a
return Name
tyname
      DPat -> QWithAux SingDSigPaInfos SgM DPat
forall (f :: * -> *) a. Applicative f => a -> f a
pure (DPat -> QWithAux SingDSigPaInfos SgM DPat)
-> DPat -> QWithAux SingDSigPaInfos SgM DPat
forall a b. (a -> b) -> a -> b
$ Name -> DPat
DVarP (Options -> Name -> Name
singledValueName Options
opts Name
name)
               DPat -> DType -> DPat
`DSigP` (DType
singFamily DType -> DType -> DType
`DAppT` Name -> DType
DVarT Name
tyname)
    go (ADConP Name
name [ADPat]
pats) = do
      Options
opts <- QWithAux SingDSigPaInfos SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
      Name -> [DPat] -> DPat
DConP (Options -> Name -> Name
singledDataConName Options
opts Name
name) ([DPat] -> DPat)
-> QWithAux SingDSigPaInfos SgM [DPat]
-> QWithAux SingDSigPaInfos SgM DPat
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (ADPat -> QWithAux SingDSigPaInfos SgM DPat)
-> [ADPat] -> QWithAux SingDSigPaInfos SgM [DPat]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ADPat -> QWithAux SingDSigPaInfos SgM DPat
go [ADPat]
pats
    go (ADTildeP ADPat
pat) = do
      String -> QWithAux SingDSigPaInfos SgM ()
forall (q :: * -> *). Quasi q => String -> q ()
qReportWarning
        String
"Lazy pattern converted into regular pattern during singleton generation."
      ADPat -> QWithAux SingDSigPaInfos SgM DPat
go ADPat
pat
    go (ADBangP ADPat
pat) = DPat -> DPat
DBangP (DPat -> DPat)
-> QWithAux SingDSigPaInfos SgM DPat
-> QWithAux SingDSigPaInfos SgM DPat
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> ADPat -> QWithAux SingDSigPaInfos SgM DPat
go ADPat
pat
    go (ADSigP DType
prom_pat ADPat
pat DType
ty) = do
      DPat
pat' <- ADPat -> QWithAux SingDSigPaInfos SgM DPat
go ADPat
pat
      -- Normally, calling dPatToDExp would be dangerous, since it fails if the
      -- supplied pattern contains any wildcard patterns. However, promotePat
      -- (which produced the pattern we're passing into dPatToDExp) maintains
      -- an invariant that any promoted pattern signatures will be free of
      -- wildcard patterns in the underlying pattern.
      -- See Note [Singling pattern signatures].
      (DExp, DType) -> QWithAux SingDSigPaInfos SgM ()
forall (q :: * -> *) elt. Quasi q => elt -> QWithAux [elt] q ()
addElement (DPat -> DExp
dPatToDExp DPat
pat', DType -> DType -> DType
DSigT DType
prom_pat DType
ty)
      DPat -> QWithAux SingDSigPaInfos SgM DPat
forall (f :: * -> *) a. Applicative f => a -> f a
pure DPat
pat'
    go ADPat
ADWildP = DPat -> QWithAux SingDSigPaInfos SgM DPat
forall (f :: * -> *) a. Applicative f => a -> f a
pure DPat
DWildP

-- | If given a non-empty list of 'SingDSigPaInfos', construct a case expression
-- that brings singleton equality constraints into scope via pattern-matching.
-- See @Note [Singling pattern signatures]@.
mkSigPaCaseE :: SingDSigPaInfos -> DExp -> DExp
mkSigPaCaseE :: SingDSigPaInfos -> DExp -> DExp
mkSigPaCaseE SingDSigPaInfos
exps_with_sigs DExp
exp
  | SingDSigPaInfos -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null SingDSigPaInfos
exps_with_sigs = DExp
exp
  | Bool
otherwise =
      let ([DExp]
exps, [DType]
sigs) = SingDSigPaInfos -> ([DExp], [DType])
forall a b. [(a, b)] -> ([a], [b])
unzip SingDSigPaInfos
exps_with_sigs
          scrutinee :: DExp
scrutinee = [DExp] -> DExp
mkTupleDExp [DExp]
exps
          pats :: [DPat]
pats = (DType -> DPat) -> [DType] -> [DPat]
forall a b. (a -> b) -> [a] -> [b]
map (DPat -> DType -> DPat
DSigP DPat
DWildP (DType -> DPat) -> (DType -> DType) -> DType -> DPat
forall b c a. (b -> c) -> (a -> b) -> a -> c
. DType -> DType -> DType
DAppT (Name -> DType
DConT Name
singFamilyName)) [DType]
sigs
      in DExp -> [DMatch] -> DExp
DCaseE DExp
scrutinee [DPat -> DExp -> DMatch
DMatch ([DPat] -> DPat
mkTupleDPat [DPat]
pats) DExp
exp]

-- Note [Annotate case return type]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- We're straining GHC's type inference here. One particular trouble area
-- is determining the return type of a GADT pattern match. In general, GHC
-- cannot infer return types of GADT pattern matches because the return type
-- becomes "untouchable" in the case matches. See the OutsideIn paper. But,
-- during singletonization, we *know* the return type. So, just add a type
-- annotation. See #54.
--
-- In particular, we add a type annotation in a somewhat unorthodox fashion.
-- Instead of the usual `(x :: t)`, we use `id @t x`. See
-- Note [The id hack; or, how singletons-th learned to stop worrying and avoid
-- kind generalization] for an explanation of why we do this.

-- Note [Why error is so special]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- Some of the transformations that happen before this point produce impossible
-- case matches. We must be careful when processing these so as not to make
-- an error GHC will complain about. When binding the case-match variables, we
-- normally include an equality constraint saying that the scrutinee is equal
-- to the matched pattern. But, we can't do this in inaccessible matches, because
-- equality is bogus, and GHC (rightly) complains. However, we then have another
-- problem, because GHC doesn't have enough information when type-checking the
-- RHS of the inaccessible match to deem it type-safe. The solution: treat error
-- as super-special, so that GHC doesn't look too hard at singletonized error
-- calls. Specifically, DON'T do the applySing stuff. Just use sError, which
-- has a custom type (Sing x -> a) anyway.

-- Note [Singling pattern signatures]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- We want to single a pattern signature, like so:
--
--   f :: Maybe a -> a
--   f (Just x :: Maybe a) = x
--
-- Naïvely, one might expect this to single straightfowardly as:
--
--   sF :: forall (z :: Maybe a). Sing z -> Sing (F z)
--   sF (SJust sX :: Sing (Just x :: Maybe a)) = sX
--
-- But the way GHC typechecks patterns prevents this from working, as GHC won't
-- know that the type `z` is actually `Just x` until /after/ the entirety of
-- the `SJust sX` pattern has been typechecked. (See Trac #12018 for an
-- extended discussion on this topic.)
--
-- To work around this design, we resort to a somewhat unsightly trick:
-- immediately after matching on all the patterns, we perform a case on every
-- pattern with a pattern signature, like so:
--
--   sF :: forall (z :: Maybe a). Sing z -> Sing (F z)
--   sF (SJust sX :: Sing z)
--     = case (SJust sX :: Sing z) of
--         (_ :: Sing (Just x :: Maybe a)) -> sX
--
-- Now GHC accepts the fact that `z` is `Just x`, and all is well. In order
-- to support this construction, the type of singPat is augmented with some
-- extra information in the form of SingDSigPaInfos:
--
--   type SingDSigPaInfos = [(DExp, DType)]
--
-- Where the DExps corresponds to the expressions we case on just after the
-- patterns (`SJust sX :: Sing x`, in the example above), and the DTypes
-- correspond to the singled pattern signatures to use in the case alternative
-- (`Sing (Just x :: Maybe a)` in the example above). singPat appends to the
-- list of SingDSigPaInfos whenever it processes a DSigPa (pattern signature),
-- and call sites can pass these SingDSigPaInfos to mkSigPaCaseE to construct a
-- case expression like the one featured above.
--
-- Some interesting consequences of this design:
--
-- 1. We must promote DPats to ADPats, a variation of DPat where the annotated
--    DSigPa counterpart, ADSigPa, stores the type that the original DPat was
--    promoted to. This is necessary since promoting the type might have
--    generated fresh variable names, so we need to be able to use the same
--    names when singling.
--
-- 2. Also when promoting a DSigPa to an ADSigPa, we remove any wildcards from
--    the underlying pattern. To see why this is necessary, consider singling
--    this example:
--
--      g (Just _ :: Maybe a) = "hi"
--
--    This must single to something like this:
--
--      sG (SJust _ :: Sing z)
--        = case (SJust _ :: Sing z) of
--            (_ :: Sing (Just _ :: Maybe a)) -> "hi"
--
--    But `SJust _` is not a valid expression, and since the minimal th-desugar
--    AST lacks as-patterns, we can't replace it with something like
--    `sG x@(SJust _ :: Sing z) = case x of ...`. But even if the th-desugar
--    AST /did/ have as-patterns, we'd still be in trouble, as `Just _` isn't
--    a valid type without the use of -XPartialTypeSignatures, which isn't a
--    design we want to force upon others.
--
--    We work around both issues by simply converting all wildcard patterns
--    from the pattern that has a signature. That means our example becomes:
--
--      sG (SJust sWild :: Sing z)
--        = case (SJust sWild :: Sing z) of
--            (_ :: Sing (Just wild :: Maybe a)) -> "hi"
--
--    And now everything is hunky-dory.

singExp :: ADExp -> Maybe DKind   -- the kind of the expression, if known
        -> SgM DExp
  -- See Note [Why error is so special]
singExp :: ADExp -> Maybe DType -> SgM DExp
singExp (ADVarE Name
err `ADAppE` ADExp
arg) Maybe DType
_res_ki
  | Name
err Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
errorName = do Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
                          DExp -> DExp -> DExp
DAppE (Name -> DExp
DVarE (Options -> Name -> Name
singledValueName Options
opts Name
err)) (DExp -> DExp) -> SgM DExp -> SgM DExp
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$>
                            ADExp -> Maybe DType -> SgM DExp
singExp ADExp
arg (DType -> Maybe DType
forall a. a -> Maybe a
Just (Name -> DType
DConT Name
symbolName))
singExp (ADVarE Name
name) Maybe DType
_res_ki = Name -> SgM DExp
lookupVarE Name
name
singExp (ADConE Name
name) Maybe DType
_res_ki = Name -> SgM DExp
lookupConE Name
name
singExp (ADLitE Lit
lit)  Maybe DType
_res_ki = Lit -> SgM DExp
singLit Lit
lit
singExp (ADAppE ADExp
e1 ADExp
e2) Maybe DType
_res_ki = do
  DExp
e1' <- ADExp -> Maybe DType -> SgM DExp
singExp ADExp
e1 Maybe DType
forall a. Maybe a
Nothing
  DExp
e2' <- ADExp -> Maybe DType -> SgM DExp
singExp ADExp
e2 Maybe DType
forall a. Maybe a
Nothing
  -- `applySing undefined x` kills type inference, because GHC can't figure
  -- out the type of `undefined`. So we don't emit `applySing` there.
  if DExp -> Bool
isException DExp
e1'
  then DExp -> SgM DExp
forall (m :: * -> *) a. Monad m => a -> m a
return (DExp -> SgM DExp) -> DExp -> SgM DExp
forall a b. (a -> b) -> a -> b
$ DExp
e1' DExp -> DExp -> DExp
`DAppE` DExp
e2'
  else DExp -> SgM DExp
forall (m :: * -> *) a. Monad m => a -> m a
return (DExp -> SgM DExp) -> DExp -> SgM DExp
forall a b. (a -> b) -> a -> b
$ (Name -> DExp
DVarE Name
applySingName) DExp -> DExp -> DExp
`DAppE` DExp
e1' DExp -> DExp -> DExp
`DAppE` DExp
e2'
singExp (ADLamE [Name]
ty_names DType
prom_lam [Name]
names ADExp
exp) Maybe DType
_res_ki = do
  Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  let sNames :: [Name]
sNames = (Name -> Name) -> [Name] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map (Options -> Name -> Name
singledValueName Options
opts) [Name]
names
  DExp
exp' <- ADExp -> Maybe DType -> SgM DExp
singExp ADExp
exp Maybe DType
forall a. Maybe a
Nothing
  -- we need to bind the type variables... but DLamE doesn't allow SigT patterns.
  -- So: build a case
  let caseExp :: DExp
caseExp = DExp -> [DMatch] -> DExp
DCaseE ([DExp] -> DExp
mkTupleDExp ((Name -> DExp) -> [Name] -> [DExp]
forall a b. (a -> b) -> [a] -> [b]
map Name -> DExp
DVarE [Name]
sNames))
                       [DPat -> DExp -> DMatch
DMatch ([DPat] -> DPat
mkTupleDPat
                                ((Name -> DPat) -> [Name] -> [DPat]
forall a b. (a -> b) -> [a] -> [b]
map ((DPat
DWildP DPat -> DType -> DPat
`DSigP`) (DType -> DPat) -> (Name -> DType) -> Name -> DPat
forall b c a. (b -> c) -> (a -> b) -> a -> c
.
                                      (DType
singFamily DType -> DType -> DType
`DAppT`) (DType -> DType) -> (Name -> DType) -> Name -> DType
forall b c a. (b -> c) -> (a -> b) -> a -> c
.
                                      Name -> DType
DVarT) [Name]
ty_names)) DExp
exp']
  DExp -> SgM DExp
forall (m :: * -> *) a. Monad m => a -> m a
return (DExp -> SgM DExp) -> DExp -> SgM DExp
forall a b. (a -> b) -> a -> b
$ Int -> DType -> DExp -> DExp
wrapSingFun ([Name] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Name]
names) DType
prom_lam (DExp -> DExp) -> DExp -> DExp
forall a b. (a -> b) -> a -> b
$ [Name] -> DExp -> DExp
DLamE [Name]
sNames DExp
caseExp
singExp (ADCaseE ADExp
exp [ADMatch]
matches DType
ret_ty) Maybe DType
res_ki =
    -- See Note [Annotate case return type] and
    --     Note [The id hack; or, how singletons-th learned to stop worrying and
    --           avoid kind generalization]
  DExp -> DExp -> DExp
DAppE (DExp -> DType -> DExp
DAppTypeE (Name -> DExp
DVarE 'id)
                   (DType
singFamily DType -> DType -> DType
`DAppT` (DType
ret_ty DType -> Maybe DType -> DType
`maybeSigT` Maybe DType
res_ki)))
    (DExp -> DExp) -> SgM DExp -> SgM DExp
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (DExp -> [DMatch] -> DExp
DCaseE (DExp -> [DMatch] -> DExp) -> SgM DExp -> SgM ([DMatch] -> DExp)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> ADExp -> Maybe DType -> SgM DExp
singExp ADExp
exp Maybe DType
forall a. Maybe a
Nothing SgM ([DMatch] -> DExp) -> SgM [DMatch] -> SgM DExp
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> (ADMatch -> SgM DMatch) -> [ADMatch] -> SgM [DMatch]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Maybe DType -> ADMatch -> SgM DMatch
singMatch Maybe DType
res_ki) [ADMatch]
matches)
singExp (ADLetE ALetDecEnv
env ADExp
exp) Maybe DType
res_ki = do
  -- We intentionally discard the SingI instances for exp's defunctionalization
  -- symbols, as we also do not generate the declarations for the
  -- defunctionalization symbols in the first place during promotion.
  ([DLetDec]
let_decs, [DDec]
_, DExp
exp') <- ALetDecEnv -> SgM DExp -> SgM ([DLetDec], [DDec], DExp)
forall a. ALetDecEnv -> SgM a -> SgM ([DLetDec], [DDec], a)
singLetDecEnv ALetDecEnv
env (SgM DExp -> SgM ([DLetDec], [DDec], DExp))
-> SgM DExp -> SgM ([DLetDec], [DDec], DExp)
forall a b. (a -> b) -> a -> b
$ ADExp -> Maybe DType -> SgM DExp
singExp ADExp
exp Maybe DType
res_ki
  DExp -> SgM DExp
forall (f :: * -> *) a. Applicative f => a -> f a
pure (DExp -> SgM DExp) -> DExp -> SgM DExp
forall a b. (a -> b) -> a -> b
$ [DLetDec] -> DExp -> DExp
DLetE [DLetDec]
let_decs DExp
exp'
singExp (ADSigE DType
prom_exp ADExp
exp DType
ty) Maybe DType
_ = do
  DExp
exp' <- ADExp -> Maybe DType -> SgM DExp
singExp ADExp
exp (DType -> Maybe DType
forall a. a -> Maybe a
Just DType
ty)
  DExp -> SgM DExp
forall (f :: * -> *) a. Applicative f => a -> f a
pure (DExp -> SgM DExp) -> DExp -> SgM DExp
forall a b. (a -> b) -> a -> b
$ DExp -> DType -> DExp
DSigE DExp
exp' (DType -> DExp) -> DType -> DExp
forall a b. (a -> b) -> a -> b
$ Name -> DType
DConT Name
singFamilyName DType -> DType -> DType
`DAppT` DType -> DType -> DType
DSigT DType
prom_exp DType
ty

-- See Note [DerivedDecl] in Data.Singletons.TH.Syntax
singDerivedEqDecs :: DerivedEqDecl -> SgM [DDec]
singDerivedEqDecs :: DerivedEqDecl -> SgM [DDec]
singDerivedEqDecs (DerivedDecl { ded_mb_cxt :: forall (cls :: * -> Constraint). DerivedDecl cls -> Maybe [DType]
ded_mb_cxt     = Maybe [DType]
mb_ctxt
                               , ded_type :: forall (cls :: * -> Constraint). DerivedDecl cls -> DType
ded_type       = DType
ty
                               , ded_type_tycon :: forall (cls :: * -> Constraint). DerivedDecl cls -> Name
ded_type_tycon = Name
ty_tycon
                               , ded_decl :: forall (cls :: * -> Constraint). DerivedDecl cls -> DataDecl
ded_decl       = DataDecl Name
_ [DTyVarBndrUnit]
_ [DCon]
cons }) = do
  ([DCon]
scons, [DDec]
_) <- [Dec] -> SgM [DCon] -> SgM ([DCon], [DDec])
forall (q :: * -> *) a.
OptionsMonad q =>
[Dec] -> SgM a -> q (a, [DDec])
singM [] (SgM [DCon] -> SgM ([DCon], [DDec]))
-> SgM [DCon] -> SgM ([DCon], [DDec])
forall a b. (a -> b) -> a -> b
$ (DCon -> SgM DCon) -> [DCon] -> SgM [DCon]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Name -> DCon -> SgM DCon
singCtor Name
ty_tycon) [DCon]
cons
  Maybe [DType]
mb_sctxt <- ([DType] -> SgM [DType]) -> Maybe [DType] -> SgM (Maybe [DType])
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((DType -> SgM DType) -> [DType] -> SgM [DType]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM DType -> SgM DType
singPred) Maybe [DType]
mb_ctxt
  DType
kind <- DType -> SgM DType
forall (m :: * -> *). OptionsMonad m => DType -> m DType
promoteType DType
ty
  -- Beware! The user might have specified an instance context like this:
  --
  --   deriving instance Eq a => Eq (T a Int)
  --
  -- When we single the context, it will become (SEq a). But we do *not* want
  -- this for the SDecide instance! The simplest solution is to simply replace
  -- all occurrences of SEq with SDecide in the context.
  Maybe [DType]
mb_sctxtDecide <- ([DType] -> SgM [DType]) -> Maybe [DType] -> SgM (Maybe [DType])
forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
(a -> f b) -> t a -> f (t b)
traverse ((DType -> SgM DType) -> [DType] -> SgM [DType]
forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
(a -> f b) -> t a -> f (t b)
traverse DType -> SgM DType
forall (m :: * -> *). OptionsMonad m => DType -> m DType
sEqToSDecide) Maybe [DType]
mb_sctxt
  DDec
sDecideInst <- Maybe [DType] -> DType -> [DCon] -> [DCon] -> SgM DDec
forall (q :: * -> *).
DsMonad q =>
Maybe [DType] -> DType -> [DCon] -> [DCon] -> q DDec
mkDecideInstance Maybe [DType]
mb_sctxtDecide DType
kind [DCon]
cons [DCon]
scons
  [DDec]
testInsts <- (TestInstance -> SgM DDec) -> [TestInstance] -> SgM [DDec]
forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
(a -> f b) -> t a -> f (t b)
traverse (Maybe [DType]
-> DType -> Name -> [DCon] -> TestInstance -> SgM DDec
forall (q :: * -> *).
OptionsMonad q =>
Maybe [DType] -> DType -> Name -> [DCon] -> TestInstance -> q DDec
mkTestInstance Maybe [DType]
mb_sctxtDecide DType
kind Name
ty_tycon [DCon]
cons)
                        [TestInstance
TestEquality, TestInstance
TestCoercion]
  [DDec] -> SgM [DDec]
forall (m :: * -> *) a. Monad m => a -> m a
return (DDec
sDecideInstDDec -> [DDec] -> [DDec]
forall a. a -> [a] -> [a]
:[DDec]
testInsts)

-- Walk a DPred, replacing all occurrences of SEq with SDecide.
sEqToSDecide :: OptionsMonad q => DPred -> q DPred
sEqToSDecide :: forall (m :: * -> *). OptionsMonad m => DType -> m DType
sEqToSDecide DType
p = do
  Options
opts <- q Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  DType -> q DType
forall (f :: * -> *) a. Applicative f => a -> f a
pure (DType -> q DType) -> DType -> q DType
forall a b. (a -> b) -> a -> b
$ (Name -> Name) -> DType -> DType
modifyConNameDType (\Name
n ->
         if Name
n Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Options -> Name -> Name
singledClassName Options
opts Name
eqName
            then Name
sDecideClassName
            else Name
n) DType
p

-- See Note [DerivedDecl] in Data.Singletons.TH.Syntax
singDerivedShowDecs :: DerivedShowDecl -> SgM [DDec]
singDerivedShowDecs :: DerivedShowDecl -> SgM [DDec]
singDerivedShowDecs (DerivedDecl { ded_mb_cxt :: forall (cls :: * -> Constraint). DerivedDecl cls -> Maybe [DType]
ded_mb_cxt     = Maybe [DType]
mb_cxt
                                 , ded_type :: forall (cls :: * -> Constraint). DerivedDecl cls -> DType
ded_type       = DType
ty
                                 , ded_type_tycon :: forall (cls :: * -> Constraint). DerivedDecl cls -> Name
ded_type_tycon = Name
ty_tycon
                                 , ded_decl :: forall (cls :: * -> Constraint). DerivedDecl cls -> DataDecl
ded_decl       = DataDecl Name
_ [DTyVarBndrUnit]
_ [DCon]
cons }) = do
    Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
    Name
z <- String -> SgM Name
forall (m :: * -> *). Quasi m => String -> m Name
qNewName String
"z"
    -- Generate a Show instance for a singleton type, like this:
    --
    --   deriving instance (ShowSing a, ShowSing b) => Sing (SEither (z :: Either a b))
    --
    -- Be careful: we want to generate an instance context that uses ShowSing,
    -- not SShow.
    [DType]
show_cxt <- Maybe [DType] -> DType -> DType -> [DCon] -> SgM [DType]
forall (q :: * -> *).
DsMonad q =>
Maybe [DType] -> DType -> DType -> [DCon] -> q [DType]
inferConstraintsDef (([DType] -> [DType]) -> Maybe [DType] -> Maybe [DType]
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap [DType] -> [DType]
mkShowSingContext Maybe [DType]
mb_cxt)
                                    (Name -> DType
DConT Name
showSingName)
                                    DType
ty [DCon]
cons
    let sty_tycon :: Name
sty_tycon = Options -> Name -> Name
singledDataTypeName Options
opts Name
ty_tycon
        show_inst :: DDec
show_inst = Maybe DDerivStrategy
-> Maybe [DTyVarBndrUnit] -> [DType] -> DType -> DDec
DStandaloneDerivD Maybe DDerivStrategy
forall a. Maybe a
Nothing Maybe [DTyVarBndrUnit]
forall a. Maybe a
Nothing [DType]
show_cxt
                      (Name -> DType
DConT Name
showName DType -> DType -> DType
`DAppT` (Name -> DType
DConT Name
sty_tycon DType -> DType -> DType
`DAppT` DType -> DType -> DType
DSigT (Name -> DType
DVarT Name
z) DType
ty))
    [DDec] -> SgM [DDec]
forall (f :: * -> *) a. Applicative f => a -> f a
pure [DDec
show_inst]

isException :: DExp -> Bool
isException :: DExp -> Bool
isException (DVarE Name
n)             = Name -> String
nameBase Name
n String -> String -> Bool
forall a. Eq a => a -> a -> Bool
== String
"sUndefined"
isException (DConE {})            = Bool
False
isException (DLitE {})            = Bool
False
isException (DAppE (DVarE Name
fun) DExp
_) | Name -> String
nameBase Name
fun String -> String -> Bool
forall a. Eq a => a -> a -> Bool
== String
"sError" = Bool
True
isException (DAppE DExp
fun DExp
_)         = DExp -> Bool
isException DExp
fun
isException (DAppTypeE DExp
e DType
_)       = DExp -> Bool
isException DExp
e
isException (DLamE [Name]
_ DExp
_)           = Bool
False
isException (DCaseE DExp
e [DMatch]
_)          = DExp -> Bool
isException DExp
e
isException (DLetE [DLetDec]
_ DExp
e)           = DExp -> Bool
isException DExp
e
isException (DSigE DExp
e DType
_)           = DExp -> Bool
isException DExp
e
isException (DStaticE DExp
e)          = DExp -> Bool
isException DExp
e

singMatch :: Maybe DKind  -- ^ the result kind, if known
          -> ADMatch -> SgM DMatch
singMatch :: Maybe DType -> ADMatch -> SgM DMatch
singMatch Maybe DType
res_ki (ADMatch VarPromotions
var_proms ADPat
pat ADExp
exp) = do
  (DPat
sPat, SingDSigPaInfos
sigPaExpsSigs) <- QWithAux SingDSigPaInfos SgM DPat -> SgM (DPat, SingDSigPaInfos)
forall m (q :: * -> *) a. QWithAux m q a -> q (a, m)
evalForPair (QWithAux SingDSigPaInfos SgM DPat -> SgM (DPat, SingDSigPaInfos))
-> QWithAux SingDSigPaInfos SgM DPat -> SgM (DPat, SingDSigPaInfos)
forall a b. (a -> b) -> a -> b
$ Map Name Name -> ADPat -> QWithAux SingDSigPaInfos SgM DPat
singPat (VarPromotions -> Map Name Name
forall k a. Ord k => [(k, a)] -> Map k a
Map.fromList VarPromotions
var_proms) ADPat
pat
  DExp
sExp <- ADExp -> Maybe DType -> SgM DExp
singExp ADExp
exp Maybe DType
res_ki
  DMatch -> SgM DMatch
forall (m :: * -> *) a. Monad m => a -> m a
return (DMatch -> SgM DMatch) -> DMatch -> SgM DMatch
forall a b. (a -> b) -> a -> b
$ DPat -> DExp -> DMatch
DMatch DPat
sPat (DExp -> DMatch) -> DExp -> DMatch
forall a b. (a -> b) -> a -> b
$ SingDSigPaInfos -> DExp -> DExp
mkSigPaCaseE SingDSigPaInfos
sigPaExpsSigs DExp
sExp

singLit :: Lit -> SgM DExp
singLit :: Lit -> SgM DExp
singLit (IntegerL Integer
n) = do
  Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  if Integer
n Integer -> Integer -> Bool
forall a. Ord a => a -> a -> Bool
>= Integer
0
     then DExp -> SgM DExp
forall (m :: * -> *) a. Monad m => a -> m a
return (DExp -> SgM DExp) -> DExp -> SgM DExp
forall a b. (a -> b) -> a -> b
$
          Name -> DExp
DVarE (Options -> Name -> Name
singledValueName Options
opts Name
fromIntegerName) DExp -> DExp -> DExp
`DAppE`
          (Name -> DExp
DVarE Name
singMethName DExp -> DType -> DExp
`DSigE`
           (DType
singFamily DType -> DType -> DType
`DAppT` TyLit -> DType
DLitT (Integer -> TyLit
NumTyLit Integer
n)))
     else do DExp
sLit <- Lit -> SgM DExp
singLit (Integer -> Lit
IntegerL (-Integer
n))
             DExp -> SgM DExp
forall (m :: * -> *) a. Monad m => a -> m a
return (DExp -> SgM DExp) -> DExp -> SgM DExp
forall a b. (a -> b) -> a -> b
$ Name -> DExp
DVarE (Options -> Name -> Name
singledValueName Options
opts Name
negateName) DExp -> DExp -> DExp
`DAppE` DExp
sLit
singLit (StringL String
str) = do
  Options
opts <- SgM Options
forall (m :: * -> *). OptionsMonad m => m Options
getOptions
  let sing_str_lit :: DExp
sing_str_lit = Name -> DExp
DVarE Name
singMethName DExp -> DType -> DExp
`DSigE`
                     (DType
singFamily DType -> DType -> DType
`DAppT` TyLit -> DType
DLitT (String -> TyLit
StrTyLit String
str))
  Bool
os_enabled <- Extension -> SgM Bool
forall (m :: * -> *). Quasi m => Extension -> m Bool
qIsExtEnabled Extension
LangExt.OverloadedStrings
  DExp -> SgM DExp
forall (f :: * -> *) a. Applicative f => a -> f a
pure (DExp -> SgM DExp) -> DExp -> SgM DExp
forall a b. (a -> b) -> a -> b
$ if Bool
os_enabled
         then Name -> DExp
DVarE (Options -> Name -> Name
singledValueName Options
opts Name
fromStringName) DExp -> DExp -> DExp
`DAppE` DExp
sing_str_lit
         else DExp
sing_str_lit
singLit Lit
lit =
  String -> SgM DExp
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String
"Only string and natural number literals can be singled: " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Lit -> String
forall a. Show a => a -> String
show Lit
lit)

{-
Note [The id hack; or, how singletons-th learned to stop worrying and avoid kind generalization]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GHC 8.8 was a time of great change. In particular, 8.8 debuted a fix for
Trac #15141 (decideKindGeneralisationPlan is too complicated). To fix this, a
wily GHC developer—who shall remain unnamed, but whose username rhymes with
schmoldfire—decided to make decideKindGeneralisationPlan less complicated by,
well, removing the whole thing. One consequence of this is that local
definitions are now kind-generalized (whereas they would not have been
previously).

While schmoldfire had the noblest of intentions when authoring his fix, he
unintentionally made life much harder for singletons-th. Why? Consider the
following program:

  class Foo a where
    bar :: a -> (a -> b) -> b
    baz :: a

  quux :: Foo a => a -> a
  quux x = x `bar` \_ -> baz

When singled, this program will turn into something like this:

  type family Quux (x :: a) :: a where
    Quux x = Bar x (LambdaSym1 x)

  sQuux :: forall a (x :: a). SFoo a => Sing x -> Sing (Quux x :: a)
  sQuux (sX :: Sing x)
    = sBar sX
        ((singFun1 @(LambdaSym1 x))
           (\ sArg
              -> case sArg of {
                   (_ :: Sing arg)
                     -> (case sArg of { _ -> sBaz }) ::
                          Sing (Case x arg arg) }))

  type family Case x arg t where
    Case x arg _ = Baz
  type family Lambda x t where
    Lambda x arg = Case x arg arg
  data LambdaSym1 x t
  type instance Apply (LambdaSym1 x) t = Lambda x t

The high-level bit is the explicit `Sing (Case x arg arg)` signature. Question:
what is the kind of `Case x arg arg`? The answer depends on whether local
definitions are kind-generalized or not!

1. If local definitions are *not* kind-generalized (i.e., the status quo before
   GHC 8.8), then `Case x arg arg :: a`.
2. If local definitions *are* kind-generalized (i.e., the status quo in GHC 8.8
   and later), then `Case x arg arg :: k` for some fresh kind variable `k`.

Unfortunately, the kind of `Case x arg arg` *must* be `a` in order for `sQuux`
to type-check. This means that the code above suddenly stopped working in GHC
8.8. What's more, we can't just remove these explicit signatures, as there is
code elsewhere in `singletons-th` that crucially relies on them to guide type
inference along (e.g., `sShowParen` in `Text.Show.Singletons`).

Luckily, there is an ingenious hack that lets us the benefits of explicit
signatures without the pain of kind generalization: our old friend, the `id`
function. The plan is as follows: instead of generating this code:

  (case sArg of ...) :: Sing (Case x arg arg)

We instead generate this code:

  id @(Sing (Case x arg arg)) (case sArg of ...)

That's it! This works because visible type arguments in terms do not get kind-
generalized, unlike top-level or local signatures. Now `Case x arg arg`'s kind
is not generalized, and all is well. We dub this: the `id` hack.

One might wonder: will we need the `id` hack around forever? Perhaps not. While
GHC 8.8 removed the decideKindGeneralisationPlan function, there have been
rumblings that a future version of GHC may bring it back (in a limited form).
If this happens, it is possibly that GHC's attitude towards kind-generalizing
local definitions may change *again*, which could conceivably render the `id`
hack unnecessary. This is all speculation, of course, so all we can do now is
wait and revisit this design at a later date.
-}