Copyright | (C) 2013 Richard Eisenberg |
---|---|
License | BSD-style (see LICENSE) |
Maintainer | Ryan Scott |
Stability | experimental |
Portability | non-portable |
Safe Haskell | None |
Language | Haskell2010 |
This module contains basic functionality for deriving your own singletons
via Template Haskell. Note that this module does not define any singled
definitions on its own. For a version of this module that comes pre-equipped
with several singled definitions based on the Prelude, see
Data.Singletons.Base.TH
from the singletons-base
library.
Synopsis
- singletons :: OptionsMonad q => q [Dec] -> q [Dec]
- singletonsOnly :: OptionsMonad q => q [Dec] -> q [Dec]
- genSingletons :: OptionsMonad q => [Name] -> q [Dec]
- promote :: OptionsMonad q => q [Dec] -> q [Dec]
- promoteOnly :: OptionsMonad q => q [Dec] -> q [Dec]
- genDefunSymbols :: OptionsMonad q => [Name] -> q [Dec]
- genPromotions :: OptionsMonad q => [Name] -> q [Dec]
- promoteEqInstances :: OptionsMonad q => [Name] -> q [Dec]
- promoteEqInstance :: OptionsMonad q => Name -> q [Dec]
- singEqInstances :: OptionsMonad q => [Name] -> q [Dec]
- singEqInstance :: OptionsMonad q => Name -> q [Dec]
- singDecideInstances :: OptionsMonad q => [Name] -> q [Dec]
- singDecideInstance :: OptionsMonad q => Name -> q [Dec]
- promoteOrdInstances :: OptionsMonad q => [Name] -> q [Dec]
- promoteOrdInstance :: OptionsMonad q => Name -> q [Dec]
- singOrdInstances :: OptionsMonad q => [Name] -> q [Dec]
- singOrdInstance :: OptionsMonad q => Name -> q [Dec]
- promoteBoundedInstances :: OptionsMonad q => [Name] -> q [Dec]
- promoteBoundedInstance :: OptionsMonad q => Name -> q [Dec]
- singBoundedInstances :: OptionsMonad q => [Name] -> q [Dec]
- singBoundedInstance :: OptionsMonad q => Name -> q [Dec]
- promoteEnumInstances :: OptionsMonad q => [Name] -> q [Dec]
- promoteEnumInstance :: OptionsMonad q => Name -> q [Dec]
- singEnumInstances :: OptionsMonad q => [Name] -> q [Dec]
- singEnumInstance :: OptionsMonad q => Name -> q [Dec]
- promoteShowInstances :: OptionsMonad q => [Name] -> q [Dec]
- promoteShowInstance :: OptionsMonad q => Name -> q [Dec]
- singShowInstances :: OptionsMonad q => [Name] -> q [Dec]
- singShowInstance :: OptionsMonad q => Name -> q [Dec]
- showSingInstances :: OptionsMonad q => [Name] -> q [Dec]
- showSingInstance :: OptionsMonad q => Name -> q [Dec]
- singITyConInstances :: DsMonad q => [Int] -> q [Dec]
- singITyConInstance :: DsMonad q => Int -> q Dec
- cases :: DsMonad q => Name -> q Exp -> q Exp -> q Exp
- sCases :: OptionsMonad q => Name -> q Exp -> q Exp -> q Exp
- module Data.Singletons
- class SDecide k where
- data (a :: k) :~: (b :: k) where
- data Void
- type Refuted a = a -> Void
- data Decision a
- class SuppressUnusedWarnings (t :: k) where
- suppressUnusedWarnings :: ()
Primary Template Haskell generation functions
singletons :: OptionsMonad q => q [Dec] -> q [Dec] Source #
Make promoted and singled versions of all declarations given, retaining
the original declarations. See the
README
for further explanation.
singletonsOnly :: OptionsMonad q => q [Dec] -> q [Dec] Source #
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.
genSingletons :: OptionsMonad q => [Name] -> q [Dec] Source #
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.
promote :: OptionsMonad q => q [Dec] -> q [Dec] Source #
Promote every declaration given to the type level, retaining the originals.
See the
README
for further explanation.
promoteOnly :: OptionsMonad q => q [Dec] -> q [Dec] Source #
Promote each declaration, discarding the originals. Note that a promoted datatype uses the same definition as an original datatype, so this will not work with datatypes. Classes, instances, and functions are all fine.
genDefunSymbols :: OptionsMonad q => [Name] -> q [Dec] Source #
genPromotions :: OptionsMonad q => [Name] -> q [Dec] Source #
Generate promoted definitions for each of the provided type-level
declaration Name
s. This is generally only useful with classes.
Functions to generate equality instances
promoteEqInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Produce instances for PEq
from the given types
promoteEqInstance :: OptionsMonad q => Name -> q [Dec] Source #
Produce an instance for PEq
from the given type
singEqInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Create instances of SEq
for the given types
singEqInstance :: OptionsMonad q => Name -> q [Dec] Source #
Create instance of SEq
for the given type
singDecideInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Create instances of SDecide
, TestEquality
, and TestCoercion
for each
type in the list.
singDecideInstance :: OptionsMonad q => Name -> q [Dec] Source #
Create instances of SDecide
, TestEquality
, and TestCoercion
for the
given type.
Functions to generate Ord
instances
promoteOrdInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Produce instances for POrd
from the given types
promoteOrdInstance :: OptionsMonad q => Name -> q [Dec] Source #
Produce an instance for POrd
from the given type
singOrdInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Create instances of SOrd
for the given types
singOrdInstance :: OptionsMonad q => Name -> q [Dec] Source #
Create instance of SOrd
for the given type
Functions to generate Bounded
instances
promoteBoundedInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Produce instances for PBounded
from the given types
promoteBoundedInstance :: OptionsMonad q => Name -> q [Dec] Source #
Produce an instance for PBounded
from the given type
singBoundedInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Create instances of SBounded
for the given types
singBoundedInstance :: OptionsMonad q => Name -> q [Dec] Source #
Create instance of SBounded
for the given type
Functions to generate Enum
instances
promoteEnumInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Produce instances for PEnum
from the given types
promoteEnumInstance :: OptionsMonad q => Name -> q [Dec] Source #
Produce an instance for PEnum
from the given type
singEnumInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Create instances of SEnum
for the given types
singEnumInstance :: OptionsMonad q => Name -> q [Dec] Source #
Create instance of SEnum
for the given type
Functions to generate Show
instances
promoteShowInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Produce instances for PShow
from the given types
promoteShowInstance :: OptionsMonad q => Name -> q [Dec] Source #
Produce an instance for PShow
from the given type
singShowInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Create instances of SShow
for the given types
(Not to be confused with showSingInstances
.)
singShowInstance :: OptionsMonad q => Name -> q [Dec] Source #
Create instance of SShow
for the given type
(Not to be confused with showShowInstance
.)
showSingInstances :: OptionsMonad q => [Name] -> q [Dec] Source #
Create instances of Show
for the given singleton types
(Not to be confused with singShowInstances
.)
showSingInstance :: OptionsMonad q => Name -> q [Dec] Source #
Create instance of Show
for the given singleton type
(Not to be confused with singShowInstance
.)
Utility functions
singITyConInstances :: DsMonad q => [Int] -> q [Dec] Source #
Create an instance for
, where SingI
TyCon{N}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 Source #
Create an instance for
, where SingI
TyCon{N}N
is the positive
number provided as an argument.
Note that the generated code requires the use of the QuantifiedConstraints
language extension.
:: DsMonad q | |
=> Name | The head of the type of the scrutinee. (Like |
-> q Exp | The scrutinee, in a Template Haskell quote |
-> q Exp | The body, in a Template Haskell quote |
-> q Exp |
The function cases
generates a case expression where each right-hand side
is identical. This may be useful if the type-checker requires knowledge of which
constructor is used to satisfy equality or type-class constraints, but where
each constructor is treated the same.
:: OptionsMonad q | |
=> Name | The head of the type the scrutinee's type is based on.
(Like |
-> q Exp | The scrutinee, in a Template Haskell quote |
-> q Exp | The body, in a Template Haskell quote |
-> q Exp |
The function sCases
generates a case expression where each right-hand side
is identical. This may be useful if the type-checker requires knowledge of which
constructor is used to satisfy equality or type-class constraints, but where
each constructor is treated the same. For sCases
, unlike cases
, the
scrutinee is a singleton. But make sure to pass in the name of the original
datatype, preferring ''Maybe
over ''SMaybe
.
Basic singleton definitions
module Data.Singletons
Auxiliary definitions
data (a :: k) :~: (b :: k) where infix 4 #
Propositional equality. If a :~: b
is inhabited by some terminating
value, then the type a
is the same as the type b
. To use this equality
in practice, pattern-match on the a :~: b
to get out the Refl
constructor;
in the body of the pattern-match, the compiler knows that a ~ b
.
Since: base-4.7.0.0
Instances
Category ((:~:) :: k -> k -> Type) | Since: base-4.7.0.0 |
TestCoercion ((:~:) a :: k -> Type) | Since: base-4.7.0.0 |
Defined in Data.Type.Coercion | |
TestEquality ((:~:) a :: k -> Type) | Since: base-4.7.0.0 |
Defined in Data.Type.Equality | |
a ~ b => Bounded (a :~: b) | Since: base-4.7.0.0 |
a ~ b => Enum (a :~: b) | Since: base-4.7.0.0 |
Defined in Data.Type.Equality | |
Eq (a :~: b) | Since: base-4.7.0.0 |
(a ~ b, Data a) => Data (a :~: b) | Since: base-4.7.0.0 |
Defined in Data.Data gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> (a :~: b) -> c (a :~: b) # gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (a :~: b) # toConstr :: (a :~: b) -> Constr # dataTypeOf :: (a :~: b) -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (a :~: b)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (a :~: b)) # gmapT :: (forall b0. Data b0 => b0 -> b0) -> (a :~: b) -> a :~: b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> (a :~: b) -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> (a :~: b) -> r # gmapQ :: (forall d. Data d => d -> u) -> (a :~: b) -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> (a :~: b) -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> (a :~: b) -> m (a :~: b) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> (a :~: b) -> m (a :~: b) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> (a :~: b) -> m (a :~: b) # | |
Ord (a :~: b) | Since: base-4.7.0.0 |
Defined in Data.Type.Equality | |
a ~ b => Read (a :~: b) | Since: base-4.7.0.0 |
Show (a :~: b) | Since: base-4.7.0.0 |
Uninhabited data type
Since: base-4.8.0.0
Instances
Eq Void | Since: base-4.8.0.0 |
Data Void | Since: base-4.8.0.0 |
Defined in Data.Void gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Void -> c Void # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Void # dataTypeOf :: Void -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Void) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Void) # gmapT :: (forall b. Data b => b -> b) -> Void -> Void # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Void -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Void -> r # gmapQ :: (forall d. Data d => d -> u) -> Void -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Void -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Void -> m Void # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Void -> m Void # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Void -> m Void # | |
Ord Void | Since: base-4.8.0.0 |
Read Void | Reading a Since: base-4.8.0.0 |
Show Void | Since: base-4.8.0.0 |
Ix Void | Since: base-4.8.0.0 |
Generic Void | Since: base-4.8.0.0 |
Semigroup Void | Since: base-4.9.0.0 |
Exception Void | Since: base-4.8.0.0 |
Defined in Data.Void toException :: Void -> SomeException # fromException :: SomeException -> Maybe Void # displayException :: Void -> String # | |
Lift Void | Since: template-haskell-2.15.0.0 |
type Rep Void | |
A Decision
about a type a
is either a proof of existence or a proof that a
cannot exist.
class SuppressUnusedWarnings (t :: k) where Source #
This class (which users should never see) is to be instantiated in order to use an otherwise-unused data constructor, such as the "kind-inference" data constructor for defunctionalization symbols.
suppressUnusedWarnings :: () Source #