Generic.Data.Internal.Enum

Generic deriving for Enum, Bounded and Ix.

Warning

This is an internal module: it is not subject to any versioning policy, breaking changes can happen at any time.

If something here seems useful, please report it or create a pull request to export it from an external module.

Documentation

gtoEnum :: (Generic a, GEnum StandardEnum (Rep a)) => Int -> a

Generic toEnum generated with the StandardEnum option.

instance Enum MyType where
  toEnum = gtoEnum
  fromEnum = gfromEnum
  enumFrom = genumFrom
  enumFromThen = genumFromThen
  enumFromTo = genumFromTo
  enumFromThenTo = genumFromThenTo

gfromEnum :: (Generic a, GEnum StandardEnum (Rep a)) => a -> Int

Generic fromEnum generated with the StandardEnum option.

See also gtoEnum.

genumFrom :: (Generic a, GEnum StandardEnum (Rep a)) => a -> [a]

Generic enumFrom generated with the StandardEnum option.

See also gtoEnum.

genumFromThen :: (Generic a, GEnum StandardEnum (Rep a)) => a -> a -> [a]

Generic enumFromThen generated with the StandardEnum option.

See also gtoEnum.

genumFromTo :: (Generic a, GEnum StandardEnum (Rep a)) => a -> a -> [a]

Generic enumFromTo generated with the StandardEnum option.

See also gtoEnum.

genumFromThenTo :: (Generic a, GEnum StandardEnum (Rep a)) => a -> a -> a -> [a]

Generic enumFromThenTo generated with the StandardEnum option.

See also gtoEnum.

gtoFiniteEnum :: (Generic a, GEnum FiniteEnum (Rep a)) => Int -> a

Generic toEnum generated with the FiniteEnum option.

instance Enum MyType where
  toEnum = gtoFiniteEnum
  fromEnum = gfromFiniteEnum
  enumFrom = gfiniteEnumFrom
  enumFromThen = gfiniteEnumFromThen
  enumFromTo = gfiniteEnumFromTo
  enumFromThenTo = gfiniteEnumFromThenTo

gfromFiniteEnum :: (Generic a, GEnum FiniteEnum (Rep a)) => a -> Int

Generic fromEnum generated with the FiniteEnum option.

See also gtoFiniteEnum.

gfiniteEnumFrom :: (Generic a, GEnum FiniteEnum (Rep a)) => a -> [a]

Generic enumFrom generated with the FiniteEnum option.

See also gtoFiniteEnum.

gfiniteEnumFromThen :: (Generic a, GEnum FiniteEnum (Rep a)) => a -> a -> [a]

Generic enumFromThen generated with the FiniteEnum option.

See also gtoFiniteEnum.

gfiniteEnumFromTo :: (Generic a, GEnum FiniteEnum (Rep a)) => a -> a -> [a]

Generic enumFromTo generated with the FiniteEnum option.

See also gtoFiniteEnum.

gfiniteEnumFromThenTo :: (Generic a, GEnum FiniteEnum (Rep a)) => a -> a -> a -> [a]

Generic enumFromThenTo generated with the FiniteEnum option.

See also gtoFiniteEnum.

gtoEnumRaw' :: forall opts a. (Generic a, GEnum opts (Rep a)) => Int -> a

Unsafe generic toEnum. Does not check whether the argument is within valid bounds. Use gtoEnum or gtoFiniteEnum instead.

gtoEnum' :: forall opts a. (Generic a, GEnum opts (Rep a)) => String -> Int -> a

Generic toEnum. Use gfromEnum or gfromFiniteEnum instead.

gfromEnum' :: forall opts a. (Generic a, GEnum opts (Rep a)) => a -> Int

Generic fromEnum. Use gfromEnum or gfromFiniteEnum instead.

genumMin :: Int

genumMin == gfromEnum gminBound

genumMax :: forall opts a. (Generic a, GEnum opts (Rep a)) => Int

genumMax == gfromEnum gmaxBound

genumFrom' :: forall opts a. (Generic a, GEnum opts (Rep a)) => a -> [a]

Generic enumFrom. Use genumFrom or gfiniteEnumFrom instead.

genumFromThen' :: forall opts a. (Generic a, GEnum opts (Rep a)) => a -> a -> [a]

Generic enumFromThen. Use genumFromThen or gfiniteEnumFromThen instead.

genumFromTo' :: forall opts a. (Generic a, GEnum opts (Rep a)) => a -> a -> [a]

Generic enumFromTo. Use genumFromTo or gfiniteEnumFromTo instead.

genumFromThenTo' :: forall opts a. (Generic a, GEnum opts (Rep a)) => a -> a -> a -> [a]

Generic enumFromThenTo. Use genumFromThenTo or gfiniteEnumFromThenTo instead.

gminBound :: (Generic a, GBounded (Rep a)) => a

Generic minBound.

instance Bounded MyType where
  minBound = gminBound
  maxBound = gmaxBound

gmaxBound :: (Generic a, GBounded (Rep a)) => a

Generic maxBound.

See also gminBound.

grange :: (Generic a, GIx (Rep a)) => (a, a) -> [a]

Generic range.

import Data.Ix
instance Ix MyType where
  range = grange
  index = gindex
  inRange = ginRange

gindex :: (Generic a, GIx (Rep a)) => (a, a) -> a -> Int

Generic index.

See also grange.

gunsafeIndex :: (Generic a, GIx (Rep a)) => (a, a) -> a -> Int

Generic unsafeIndex.

Details

The functions unsafeIndex and unsafeRangeSize belong to Ix but are internal to GHC and hence not exported from the module Data.Ix. However they are exported from the module GHC.Arr. See grange for how to define an instance of Ix such that it does not depend on the stability of GHCs internal API. Unfortunately this results in additional (unnecessary) bound checks. With the danger of having no stability guarantees for GHC's internal API one can alternatively define an instance of Ix as

import GHC.Arr
instance Ix MyType where
  range = grange
  unsafeIndex = gunsafeIndex
  inRange = ginRange

ginRange :: (Generic a, GIx (Rep a)) => (a, a) -> a -> Bool

Generic inRange.

See also grange.

class GEnum opts f where

Generic representation of Enum types.

The opts parameter is a type-level option to select different implementations.

Methods

gCardinality :: Int

gFromEnum :: f p -> Int

gToEnum :: Int -> f p

Instances

GEnum opts (U1 :: Type -> Type)

Defined in Generic.Data.Internal.Enum

Methods

gCardinality :: Int

gFromEnum :: U1 p -> Int

gToEnum :: Int -> U1 p

(GEnum opts f, GEnum opts g) => GEnum opts (f :+: g)

Defined in Generic.Data.Internal.Enum

Methods

gCardinality :: Int

gFromEnum :: (f :+: g) p -> Int

gToEnum :: Int -> (f :+: g) p

(Bounded c, Enum c) => GEnum FiniteEnum (K1 i c :: Type -> Type)

Defined in Generic.Data.Internal.Enum

Methods

gCardinality :: Int

gFromEnum :: K1 i c p -> Int

gToEnum :: Int -> K1 i c p

(GEnum FiniteEnum f, GEnum FiniteEnum g) => GEnum FiniteEnum (f :*: g)

Defined in Generic.Data.Internal.Enum

Methods

gCardinality :: Int

gFromEnum :: (f :*: g) p -> Int

gToEnum :: Int -> (f :*: g) p

GEnum opts f => GEnum opts (M1 i c f)

Defined in Generic.Data.Internal.Enum

Methods

gCardinality :: Int

gFromEnum :: M1 i c f p -> Int

gToEnum :: Int -> M1 i c f p

data StandardEnum

Standard option for GEnum: derive Enum for types with only nullary constructors (the same restrictions as in the Haskell 2010 report).

data FiniteEnum

Extends the StandardEnum option for GEnum to allow all constructors to have arbitrary many fields. Each field type must be an instance of both Enum and Bounded. Avoid fields of types Int and Word.

Details

Two restrictions require the user's attention:

• The Enum instances of the field types need to start enumerating from 0. In particular, Int is an unfit field type, because the enumeration of the negative values starts before 0.
• There can only be up to maxBound :: Int values (because the implementation represents the cardinality explicitly as an Int). This restriction makes Word an invalid field type as well. Notably, it is insufficient for each individual field types to stay below this limit. Instead it applies to the generic type as a whole.

Elements are numbered by toEnum, from 0 up to (cardinality - 1). The resulting ordering matches the generic Ord instance defined by gcompare. The values from different constructors are enumerated sequentially.

data Example = C0 Bool Bool | C1 Bool
  deriving (Eq, Ord, Show, Generic)

cardinality = 6  -- 2    * 2    + 2
                 -- Bool * Bool | Bool

enumeration =
    [ C0 False False
    , C0 False  True
    , C0  True False
    , C0  True  True
    , C1 False
    , C1 True
    ]

enumeration == map gtoFiniteEnum [0 .. 5]
[0 .. 5] == map gfromFiniteEnum enumeration

Instances

(Bounded c, Enum c) => GEnum FiniteEnum (K1 i c :: Type -> Type)

Defined in Generic.Data.Internal.Enum

Methods

gCardinality :: Int

gFromEnum :: K1 i c p -> Int

gToEnum :: Int -> K1 i c p

(GEnum FiniteEnum f, GEnum FiniteEnum g) => GEnum FiniteEnum (f :*: g)

Defined in Generic.Data.Internal.Enum

Methods

gCardinality :: Int

gFromEnum :: (f :*: g) p -> Int

gToEnum :: Int -> (f :*: g) p

class GBounded f where

Generic representation of Bounded types.

Methods

gMinBound :: f p

gMaxBound :: f p

Instances

GBounded (U1 :: Type -> Type)

Defined in Generic.Data.Internal.Enum

Methods

gMinBound :: U1 p

gMaxBound :: U1 p

Bounded c => GBounded (K1 i c :: Type -> Type)

Defined in Generic.Data.Internal.Enum

Methods

gMinBound :: K1 i c p

gMaxBound :: K1 i c p

(GBounded f, GBounded g) => GBounded (f :+: g)

Defined in Generic.Data.Internal.Enum

Methods

gMinBound :: (f :+: g) p

gMaxBound :: (f :+: g) p

(GBounded f, GBounded g) => GBounded (f :*: g)

Defined in Generic.Data.Internal.Enum

Methods

gMinBound :: (f :*: g) p

gMaxBound :: (f :*: g) p

GBounded f => GBounded (M1 i c f)

Defined in Generic.Data.Internal.Enum

Methods

gMinBound :: M1 i c f p

gMaxBound :: M1 i c f p

class GIx f where

Generic representation of Ix types.

Methods

gRange :: (f p, f p) -> [f p]

gUnsafeIndex :: (f p, f p) -> f p -> Int

gInRange :: (f p, f p) -> f p -> Bool

Instances

GIx (U1 :: Type -> Type)

Defined in Generic.Data.Internal.Enum

Methods

gRange :: (U1 p, U1 p) -> [U1 p]

gUnsafeIndex :: (U1 p, U1 p) -> U1 p -> Int

gInRange :: (U1 p, U1 p) -> U1 p -> Bool

Ix c => GIx (K1 i c :: Type -> Type)

Defined in Generic.Data.Internal.Enum

Methods

gRange :: (K1 i c p, K1 i c p) -> [K1 i c p]

gUnsafeIndex :: (K1 i c p, K1 i c p) -> K1 i c p -> Int

gInRange :: (K1 i c p, K1 i c p) -> K1 i c p -> Bool

(GEnum StandardEnum f, GEnum StandardEnum g) => GIx (f :+: g)

Defined in Generic.Data.Internal.Enum

Methods

gRange :: ((f :+: g) p, (f :+: g) p) -> [(f :+: g) p]

gUnsafeIndex :: ((f :+: g) p, (f :+: g) p) -> (f :+: g) p -> Int

gInRange :: ((f :+: g) p, (f :+: g) p) -> (f :+: g) p -> Bool

(GIx f, GIx g) => GIx (f :*: g)

Defined in Generic.Data.Internal.Enum

Methods

gRange :: ((f :*: g) p, (f :*: g) p) -> [(f :*: g) p]

gUnsafeIndex :: ((f :*: g) p, (f :*: g) p) -> (f :*: g) p -> Int

gInRange :: ((f :*: g) p, (f :*: g) p) -> (f :*: g) p -> Bool

GIx f => GIx (M1 i c f)

Defined in Generic.Data.Internal.Enum

Methods

gRange :: (M1 i c f p, M1 i c f p) -> [M1 i c f p]

gUnsafeIndex :: (M1 i c f p, M1 i c f p) -> M1 i c f p -> Int

gInRange :: (M1 i c f p, M1 i c f p) -> M1 i c f p -> Bool