Generics.Eot

generics-eot tries to be a library for datatype generic programming that is easy to understand. "eot" stands for "eithers of tuples".

A tutorial on how to use generics-eot can be found here: https://generics-eot.readthedocs.io/.

Documentation

class HasEot a where

An instance (HasEot a) allows us to

• convert values of an arbitrary algebraic datatype a to and from a generic representation (Eot a) (see toEot and fromEot).
• extract meta information about the type a (see datatype).

Once an algebraic datatype has an instance for Generic it automatically gets one for HasEot.

Minimal complete definition

toEot, fromEot, datatype

Associated Types

type Eot a :: *

Eot is a type level function that maps arbitrary ADTs to isomorphic generic representations. Here's an example:

data Foo = A Int Bool | B String

would be mapped to:

Either (Int, (Bool, ())) (Either (String, ()) Void)

These representations follow these rules:

• The choice between constructors is mapped to right-nested Eithers.
• There's always a so-called end-marker Void. It's an invalid choice (and Void is uninhabited to make sure you don't accidentally create such a value). So e.g. data Foo = A would be mapped to Either () Void, and a type with no constructors is mapped to Void.
• The fields of one constructor are mapped to right-nested tuples.
• Again there's always an end-marker, this time of type (). A constructor with three fields a, b, c is mapped to (a, (b, (c, ()))), one field a is mapped to (a, ()), and no fields are mapped to () (just the end-marker).

These rules (and the end-markers) are necessary to make sure generic functions know exactly which parts of the generic representation are field types and which parts belong to the generic skeleton.

Methods

toEot :: a -> Eot a

Convert a value of type a to its generic representation.

fromEot :: Eot a -> a

Convert a value in a generic representation to a (inverse of toEot).

datatype :: Proxy a -> Datatype

Extract meta information about the ADT.

Instances

(Generic a, ImpliedByGeneric a c f) => HasEot a

Associated Types

type Eot a :: *

Methods

toEot :: a -> Eot a

fromEot :: Eot a -> a

datatype :: Proxy * a -> Datatype

Meta Information

data Datatype

Type for meta information about ADTs.

Constructors

Datatype

Fields

• datatypeName :: String

  unqualified name of the type

• constructors :: [Constructor]

Instances

Eq Datatype

Methods

(==) :: Datatype -> Datatype -> Bool

(/=) :: Datatype -> Datatype -> Bool

Show Datatype

Methods

showsPrec :: Int -> Datatype -> ShowS

show :: Datatype -> String

showList :: [Datatype] -> ShowS

data Constructor

Constructors

Constructor

Fields

• constructorName :: String
• fields :: Fields

Instances

Eq Constructor

Methods

(==) :: Constructor -> Constructor -> Bool

(/=) :: Constructor -> Constructor -> Bool

Show Constructor

Methods

showsPrec :: Int -> Constructor -> ShowS

show :: Constructor -> String

showList :: [Constructor] -> ShowS

data Fields

Type that represents meta information about fields of one constructor.

Constructors

Selectors [String]

Record constructor, containing the list of the selector names.

NoSelectors Int

Constructor with fields, but without selector names. The argument gives the number of fields.

NoFields

Constructor without fields.

Instances

Eq Fields

Methods

(==) :: Fields -> Fields -> Bool

(/=) :: Fields -> Fields -> Bool

Show Fields

Methods

showsPrec :: Int -> Fields -> ShowS

show :: Fields -> String

showList :: [Fields] -> ShowS

Useful Re-exports

class Generic a

Representable types of kind *. This class is derivable in GHC with the DeriveGeneric flag on.

Minimal complete definition

from, to

Instances

Generic Bool

Associated Types

type Rep Bool :: * -> *

Methods

from :: Bool -> Rep Bool x

to :: Rep Bool x -> Bool

Generic Ordering

Associated Types

type Rep Ordering :: * -> *

Methods

from :: Ordering -> Rep Ordering x

to :: Rep Ordering x -> Ordering

Generic ()

Associated Types

type Rep () :: * -> *

Methods

from :: () -> Rep () x

to :: Rep () x -> ()

Generic Void

Associated Types

type Rep Void :: * -> *

Methods

from :: Void -> Rep Void x

to :: Rep Void x -> Void

Generic Version

Associated Types

type Rep Version :: * -> *

Methods

from :: Version -> Rep Version x

to :: Rep Version x -> Version

Generic ExitCode

Associated Types

type Rep ExitCode :: * -> *

Methods

from :: ExitCode -> Rep ExitCode x

to :: Rep ExitCode x -> ExitCode

Generic Fixity

Associated Types

type Rep Fixity :: * -> *

Methods

from :: Fixity -> Rep Fixity x

to :: Rep Fixity x -> Fixity

Generic Associativity

Associated Types

type Rep Associativity :: * -> *

Methods

from :: Associativity -> Rep Associativity x

to :: Rep Associativity x -> Associativity

Generic SourceUnpackedness

Associated Types

type Rep SourceUnpackedness :: * -> *

Methods

from :: SourceUnpackedness -> Rep SourceUnpackedness x

to :: Rep SourceUnpackedness x -> SourceUnpackedness

Generic SourceStrictness

Associated Types

type Rep SourceStrictness :: * -> *

Methods

from :: SourceStrictness -> Rep SourceStrictness x

to :: Rep SourceStrictness x -> SourceStrictness

Generic DecidedStrictness

Associated Types

type Rep DecidedStrictness :: * -> *

Methods

from :: DecidedStrictness -> Rep DecidedStrictness x

to :: Rep DecidedStrictness x -> DecidedStrictness

Generic [a]

Associated Types

type Rep [a] :: * -> *

Methods

from :: [a] -> Rep [a] x

to :: Rep [a] x -> [a]

Generic (Maybe a)

Associated Types

type Rep (Maybe a) :: * -> *

Methods

from :: Maybe a -> Rep (Maybe a) x

to :: Rep (Maybe a) x -> Maybe a

Generic (Par1 p)

Associated Types

type Rep (Par1 p) :: * -> *

Methods

from :: Par1 p -> Rep (Par1 p) x

to :: Rep (Par1 p) x -> Par1 p

Generic (Either a b)

Associated Types

type Rep (Either a b) :: * -> *

Methods

from :: Either a b -> Rep (Either a b) x

to :: Rep (Either a b) x -> Either a b

Generic (V1 k p)

Associated Types

type Rep (V1 k p) :: * -> *

Methods

from :: V1 k p -> Rep (V1 k p) x

to :: Rep (V1 k p) x -> V1 k p

Generic (U1 k p)

Associated Types

type Rep (U1 k p) :: * -> *

Methods

from :: U1 k p -> Rep (U1 k p) x

to :: Rep (U1 k p) x -> U1 k p

Generic (a, b)

Associated Types

type Rep (a, b) :: * -> *

Methods

from :: (a, b) -> Rep (a, b) x

to :: Rep (a, b) x -> (a, b)

Generic (Proxy k t)

Associated Types

type Rep (Proxy k t) :: * -> *

Methods

from :: Proxy k t -> Rep (Proxy k t) x

to :: Rep (Proxy k t) x -> Proxy k t

Generic (Rec1 k f p)

Associated Types

type Rep (Rec1 k f p) :: * -> *

Methods

from :: Rec1 k f p -> Rep (Rec1 k f p) x

to :: Rep (Rec1 k f p) x -> Rec1 k f p

Generic (URec k (Ptr ()) p)

Associated Types

type Rep (URec k (Ptr ()) p) :: * -> *

Methods

from :: URec k (Ptr ()) p -> Rep (URec k (Ptr ()) p) x

to :: Rep (URec k (Ptr ()) p) x -> URec k (Ptr ()) p

Generic (URec k Char p)

Associated Types

type Rep (URec k Char p) :: * -> *

Methods

from :: URec k Char p -> Rep (URec k Char p) x

to :: Rep (URec k Char p) x -> URec k Char p

Generic (URec k Double p)

Associated Types

type Rep (URec k Double p) :: * -> *

Methods

from :: URec k Double p -> Rep (URec k Double p) x

to :: Rep (URec k Double p) x -> URec k Double p

Generic (URec k Float p)

Associated Types

type Rep (URec k Float p) :: * -> *

Methods

from :: URec k Float p -> Rep (URec k Float p) x

to :: Rep (URec k Float p) x -> URec k Float p

Generic (URec k Int p)

Associated Types

type Rep (URec k Int p) :: * -> *

Methods

from :: URec k Int p -> Rep (URec k Int p) x

to :: Rep (URec k Int p) x -> URec k Int p

Generic (URec k Word p)

Associated Types

type Rep (URec k Word p) :: * -> *

Methods

from :: URec k Word p -> Rep (URec k Word p) x

to :: Rep (URec k Word p) x -> URec k Word p

Generic (a, b, c)

Associated Types

type Rep (a, b, c) :: * -> *

Methods

from :: (a, b, c) -> Rep (a, b, c) x

to :: Rep (a, b, c) x -> (a, b, c)

Generic (K1 k i c p)

Associated Types

type Rep (K1 k i c p) :: * -> *

Methods

from :: K1 k i c p -> Rep (K1 k i c p) x

to :: Rep (K1 k i c p) x -> K1 k i c p

Generic ((:+:) k f g p)

Associated Types

type Rep ((k :+: f) g p) :: * -> *

Methods

from :: (k :+: f) g p -> Rep ((k :+: f) g p) x

to :: Rep ((k :+: f) g p) x -> (k :+: f) g p

Generic ((:*:) k f g p)

Associated Types

type Rep ((k :*: f) g p) :: * -> *

Methods

from :: (k :*: f) g p -> Rep ((k :*: f) g p) x

to :: Rep ((k :*: f) g p) x -> (k :*: f) g p

Generic (a, b, c, d)

Associated Types

type Rep (a, b, c, d) :: * -> *

Methods

from :: (a, b, c, d) -> Rep (a, b, c, d) x

to :: Rep (a, b, c, d) x -> (a, b, c, d)

Generic (M1 k i c f p)

Associated Types

type Rep (M1 k i c f p) :: * -> *

Methods

from :: M1 k i c f p -> Rep (M1 k i c f p) x

to :: Rep (M1 k i c f p) x -> M1 k i c f p

Generic ((:.:) k2 k1 f g p)

Associated Types

type Rep ((k2 :.: k1) f g p) :: * -> *

Methods

from :: (k2 :.: k1) f g p -> Rep ((k2 :.: k1) f g p) x

to :: Rep ((k2 :.: k1) f g p) x -> (k2 :.: k1) f g p

Generic (a, b, c, d, e)

Associated Types

type Rep (a, b, c, d, e) :: * -> *

Methods

from :: (a, b, c, d, e) -> Rep (a, b, c, d, e) x

to :: Rep (a, b, c, d, e) x -> (a, b, c, d, e)

Generic (a, b, c, d, e, f)

Associated Types

type Rep (a, b, c, d, e, f) :: * -> *

Methods

from :: (a, b, c, d, e, f) -> Rep (a, b, c, d, e, f) x

to :: Rep (a, b, c, d, e, f) x -> (a, b, c, d, e, f)

Generic (a, b, c, d, e, f, g)

Associated Types

type Rep (a, b, c, d, e, f, g) :: * -> *

Methods

from :: (a, b, c, d, e, f, g) -> Rep (a, b, c, d, e, f, g) x

to :: Rep (a, b, c, d, e, f, g) x -> (a, b, c, d, e, f, g)

data Proxy k (t :: k) :: forall k. k -> *

A concrete, poly-kinded proxy type

Constructors

Proxy

Instances

Generic1 k (Proxy k)

Associated Types

type Rep1 (Proxy k) (f :: Proxy k -> *) :: k -> *

Methods

from1 :: f a -> Rep1 (Proxy k) f a

to1 :: Rep1 (Proxy k) f a -> f a

Monad (Proxy *)

Since: 4.7.0.0

Methods

(>>=) :: Proxy * a -> (a -> Proxy * b) -> Proxy * b

(>>) :: Proxy * a -> Proxy * b -> Proxy * b

return :: a -> Proxy * a

fail :: String -> Proxy * a

Functor (Proxy *)

Since: 4.7.0.0

Methods

fmap :: (a -> b) -> Proxy * a -> Proxy * b

(<$) :: a -> Proxy * b -> Proxy * a

Applicative (Proxy *)

Since: 4.7.0.0

Methods

pure :: a -> Proxy * a

(<*>) :: Proxy * (a -> b) -> Proxy * a -> Proxy * b

liftA2 :: (a -> b -> c) -> Proxy * a -> Proxy * b -> Proxy * c

(*>) :: Proxy * a -> Proxy * b -> Proxy * b

(<*) :: Proxy * a -> Proxy * b -> Proxy * a

Foldable (Proxy *)

Since: 4.7.0.0

Methods

fold :: Monoid m => Proxy * m -> m

foldMap :: Monoid m => (a -> m) -> Proxy * a -> m

foldr :: (a -> b -> b) -> b -> Proxy * a -> b

foldr' :: (a -> b -> b) -> b -> Proxy * a -> b

foldl :: (b -> a -> b) -> b -> Proxy * a -> b

foldl' :: (b -> a -> b) -> b -> Proxy * a -> b

foldr1 :: (a -> a -> a) -> Proxy * a -> a

foldl1 :: (a -> a -> a) -> Proxy * a -> a

toList :: Proxy * a -> [a]

null :: Proxy * a -> Bool

length :: Proxy * a -> Int

elem :: Eq a => a -> Proxy * a -> Bool

maximum :: Ord a => Proxy * a -> a

minimum :: Ord a => Proxy * a -> a

sum :: Num a => Proxy * a -> a

product :: Num a => Proxy * a -> a

Alternative (Proxy *)

Since: 4.9.0.0

Methods

empty :: Proxy * a

(<|>) :: Proxy * a -> Proxy * a -> Proxy * a

some :: Proxy * a -> Proxy * [a]

many :: Proxy * a -> Proxy * [a]

MonadPlus (Proxy *)

Since: 4.9.0.0

Methods

mzero :: Proxy * a

mplus :: Proxy * a -> Proxy * a -> Proxy * a

Bounded (Proxy k t)

Methods

minBound :: Proxy k t

maxBound :: Proxy k t

Enum (Proxy k s)

Since: 4.7.0.0

Methods

succ :: Proxy k s -> Proxy k s

pred :: Proxy k s -> Proxy k s

toEnum :: Int -> Proxy k s

fromEnum :: Proxy k s -> Int

enumFrom :: Proxy k s -> [Proxy k s]

enumFromThen :: Proxy k s -> Proxy k s -> [Proxy k s]

enumFromTo :: Proxy k s -> Proxy k s -> [Proxy k s]

enumFromThenTo :: Proxy k s -> Proxy k s -> Proxy k s -> [Proxy k s]

Eq (Proxy k s)

Since: 4.7.0.0

Methods

(==) :: Proxy k s -> Proxy k s -> Bool

(/=) :: Proxy k s -> Proxy k s -> Bool

Ord (Proxy k s)

Since: 4.7.0.0

Methods

compare :: Proxy k s -> Proxy k s -> Ordering

(<) :: Proxy k s -> Proxy k s -> Bool

(<=) :: Proxy k s -> Proxy k s -> Bool

(>) :: Proxy k s -> Proxy k s -> Bool

(>=) :: Proxy k s -> Proxy k s -> Bool

max :: Proxy k s -> Proxy k s -> Proxy k s

min :: Proxy k s -> Proxy k s -> Proxy k s

Read (Proxy k s)

Since: 4.7.0.0

Methods

readsPrec :: Int -> ReadS (Proxy k s)

readList :: ReadS [Proxy k s]

readPrec :: ReadPrec (Proxy k s)

readListPrec :: ReadPrec [Proxy k s]

Show (Proxy k s)

Since: 4.7.0.0

Methods

showsPrec :: Int -> Proxy k s -> ShowS

show :: Proxy k s -> String

showList :: [Proxy k s] -> ShowS

Ix (Proxy k s)

Since: 4.7.0.0

Methods

range :: (Proxy k s, Proxy k s) -> [Proxy k s]

index :: (Proxy k s, Proxy k s) -> Proxy k s -> Int

unsafeIndex :: (Proxy k s, Proxy k s) -> Proxy k s -> Int

inRange :: (Proxy k s, Proxy k s) -> Proxy k s -> Bool

rangeSize :: (Proxy k s, Proxy k s) -> Int

unsafeRangeSize :: (Proxy k s, Proxy k s) -> Int

Generic (Proxy k t)

Associated Types

type Rep (Proxy k t) :: * -> *

Methods

from :: Proxy k t -> Rep (Proxy k t) x

to :: Rep (Proxy k t) x -> Proxy k t

Monoid (Proxy k s)

Since: 4.7.0.0

Methods

mempty :: Proxy k s

mappend :: Proxy k s -> Proxy k s -> Proxy k s

mconcat :: [Proxy k s] -> Proxy k s

type Rep1 k (Proxy k)

type Rep1 k (Proxy k) = D1 k (MetaData "Proxy" "Data.Proxy" "base" False) (C1 k (MetaCons "Proxy" PrefixI False) (U1 k))

type Rep (Proxy k t)

type Rep (Proxy k t) = D1 * (MetaData "Proxy" "Data.Proxy" "base" False) (C1 * (MetaCons "Proxy" PrefixI False) (U1 *))

data Void :: *

Uninhabited data type

Since: 4.8.0.0

Instances

Eq Void

Since: 4.8.0.0

Methods

(==) :: Void -> Void -> Bool

(/=) :: Void -> Void -> Bool

Data Void

Methods

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

toConstr :: Void -> Constr

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 :: (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: 4.8.0.0

Methods

compare :: Void -> Void -> Ordering

(<) :: Void -> Void -> Bool

(<=) :: Void -> Void -> Bool

(>) :: Void -> Void -> Bool

(>=) :: Void -> Void -> Bool

max :: Void -> Void -> Void

min :: Void -> Void -> Void

Read Void

Reading a Void value is always a parse error, considering Void as a data type with no constructors. | @since 4.8.0.0

Methods

readsPrec :: Int -> ReadS Void

readList :: ReadS [Void]

readPrec :: ReadPrec Void

readListPrec :: ReadPrec [Void]

Show Void

Since: 4.8.0.0

Methods

showsPrec :: Int -> Void -> ShowS

show :: Void -> String

showList :: [Void] -> ShowS

Ix Void

Since: 4.8.0.0

Methods

range :: (Void, Void) -> [Void]

index :: (Void, Void) -> Void -> Int

unsafeIndex :: (Void, Void) -> Void -> Int

inRange :: (Void, Void) -> Void -> Bool

rangeSize :: (Void, Void) -> Int

unsafeRangeSize :: (Void, Void) -> Int

Generic Void

Associated Types

type Rep Void :: * -> *

Methods

from :: Void -> Rep Void x

to :: Rep Void x -> Void

Exception Void

Since: 4.8.0.0

Methods

toException :: Void -> SomeException

fromException :: SomeException -> Maybe Void

displayException :: Void -> String

type Rep Void

type Rep Void = D1 * (MetaData "Void" "Data.Void" "base" False) (V1 *)

absurd :: Void -> a

Since Void values logically don't exist, this witnesses the logical reasoning tool of "ex falso quodlibet".

Since: 4.8.0.0