-{-# LANGUAGE DeriveDataTypeable,
- FlexibleContexts,
- FlexibleInstances,
- MultiParamTypeClasses,
- TypeFamilies,
- TypeOperators,
- UndecidableInstances
+{- -*- coding: utf-8 -*- -}
+{-# LANGUAGE
+ DeriveDataTypeable,
+ EmptyDataDecls,
+ FlexibleContexts,
+ FlexibleInstances,
+ FunctionalDependencies,
+ MultiParamTypeClasses,
+ OverlappingInstances,
+ TypeFamilies,
+ TypeOperators,
+ UndecidableInstances
#-}
module Data.HList.Prelude
- ( HList
+ ( List
- , HNil(..)
+ , Nil(..)
, hNil
- , HCons(..)
+ , Cons(..)
, hCons
- , HExtendable(..)
- , HAppendable(..)
+ , ExtendT(..)
+ , AppendT(..)
- , Applyable(..)
- , Applyable2(..)
+ , ApplyT(..)
+ , Apply2T(..)
, Id(..)
- , ApplyHAppend(..)
+ , AppendA(..)
- , HFoldrable(..)
- , HConcatable(..)
- , HMappable(..)
+ , FoldrT(..)
+ , ConcatT(..)
+ , MapT(..)
+
+ , All
+ , Length
+
+ , Fail
+ , TypeFound
+ , TypeNotFound
+ , OccursMany(..)
+ , OccursMany1(..)
+ , OccursOpt(..)
+ , Occurs(..)
+ , OccursNot
+
+ , NoDuplicates
)
where
import Data.Typeable
+import Types.Data.Bool
+import Types.Data.Num hiding ((:*:))
--- HList
-class HList l
+-- List
+class List l
--- HNil
-data HNil
- = HNil
+-- Nil
+data Nil
+ = Nil
deriving (Show, Eq, Ord, Read, Typeable)
-instance HList HNil
+instance List Nil
-hNil :: HNil
-hNil = HNil
+hNil :: Nil
+hNil = Nil
--- HCons
-data HCons e l
- = HCons e l
+-- Cons
+data Cons e l
+ = Cons e l
deriving (Show, Eq, Ord, Read, Typeable)
-instance HList l => HList (HCons e l)
+instance List l => List (Cons e l)
-hCons :: HList l => e -> l -> HCons e l
-hCons = HCons
+hCons :: List l => e -> l -> Cons e l
+hCons = Cons
--- HExtendable
-infixr 2 :*:
-infixr 2 .*.
+-- ExtendT
+infixr 2 :&:
+infixr 2 .&.
-class HExtendable e l where
- type e :*: l
- (.*.) :: e -> l -> e :*: l
+class ExtendT e l where
+ type e :&: l
+ (.&.) :: e -> l -> e :&: l
-instance HExtendable e HNil where
- type e :*: HNil = HCons e HNil
- e .*. nil = hCons e nil
+instance ExtendT e Nil where
+ type e :&: Nil = Cons e Nil
+ e .&. nil = hCons e nil
-instance HList l => HExtendable e (HCons e' l) where
- type e :*: HCons e' l = HCons e (HCons e' l)
- e .*. HCons e' l = hCons e (hCons e' l)
+instance List l => ExtendT e (Cons e' l) where
+ type e :&: Cons e' l = Cons e (Cons e' l)
+ e .&. Cons e' l = hCons e (hCons e' l)
--- HAppendable
+-- AppendT
infixr 1 :++:
infixr 1 .++.
-class HAppendable l l' where
+class AppendT l l' where
type l :++: l'
(.++.) :: l -> l' -> l :++: l'
-instance HList l => HAppendable HNil l where
- type HNil :++: l = l
+instance List l => AppendT Nil l where
+ type Nil :++: l = l
_ .++. l = l
-instance ( HList (l :++: l')
- , HAppendable l l'
- ) => HAppendable (HCons e l) l' where
- type HCons e l :++: l' = HCons e (l :++: l')
- (HCons e l) .++. l' = hCons e (l .++. l')
+instance ( List (l :++: l')
+ , AppendT l l'
+ ) => AppendT (Cons e l) l' where
+ type Cons e l :++: l' = Cons e (l :++: l')
+ (Cons e l) .++. l' = hCons e (l .++. l')
--- Applyable
-class Applyable f a where
+-- ApplyT
+class ApplyT f a where
type Apply f a
apply :: f -> a -> Apply f a
+ apply _ _ = undefined
--- Applyable2
-class Applyable2 f a b where
+-- Apply2T
+class Apply2T f a b where
type Apply2 f a b
apply2 :: f -> a -> b -> Apply2 f a b
+ apply2 _ _ _ = undefined
-- Id
data Id = Id
-instance Applyable Id a where
+instance ApplyT Id a where
type Apply Id a = a
apply _ a = a
--- ApplyHAppend
-data ApplyHAppend = ApplyHAppend
+-- AppendA
+data AppendA = AppendA
-instance HAppendable a b => Applyable2 ApplyHAppend a b where
- type Apply2 ApplyHAppend a b = a :++: b
+instance AppendT a b => Apply2T AppendA a b where
+ type Apply2 AppendA a b = a :++: b
apply2 _ a b = a .++. b
--- HFoldrable
-class HFoldrable f v l where
- type HFoldr f v l
- hFoldr :: f -> v -> l -> HFoldr f v l
+-- FoldrT
+class FoldrT f v l where
+ type Foldr f v l
+ hFoldr :: f -> v -> l -> Foldr f v l
-instance HFoldrable f v HNil where
- type HFoldr f v HNil = v
+instance FoldrT f v Nil where
+ type Foldr f v Nil = v
hFoldr _ v _ = v
-instance ( HFoldrable f v l
- , Applyable2 f e (HFoldr f v l)
- ) => HFoldrable f v (HCons e l) where
- type HFoldr f v (HCons e l) = Apply2 f e (HFoldr f v l)
- hFoldr f v (HCons e l) = apply2 f e (hFoldr f v l)
+instance ( FoldrT f v l
+ , Apply2T f e (Foldr f v l)
+ ) => FoldrT f v (Cons e l) where
+ type Foldr f v (Cons e l) = Apply2 f e (Foldr f v l)
+ hFoldr f v (Cons e l) = apply2 f e (hFoldr f v l)
--- HConcatable
-class HConcatable ls where
- type HConcat ls
- hConcat :: ls -> HConcat ls
+-- ConcatT
+class ConcatT ls where
+ type Concat ls
+ hConcat :: ls -> Concat ls
-instance HFoldrable ApplyHAppend HNil ls => HConcatable ls where
- type HConcat ls = HFoldr ApplyHAppend HNil ls
- hConcat ls = hFoldr ApplyHAppend hNil ls
+instance FoldrT AppendA Nil ls => ConcatT ls where
+ type Concat ls = Foldr AppendA Nil ls
+ hConcat ls = hFoldr AppendA hNil ls
--- HMappable
-class HMappable f l where
- type HMap f l
- hMap :: f -> l -> HMap f l
+-- MapT
+class MapT f l where
+ type Map f l
+ hMap :: f -> l -> Map f l
-instance HMappable f HNil where
- type HMap f HNil = HNil
+instance MapT f Nil where
+ type Map f Nil = Nil
hMap _ _ = hNil
-instance ( Applyable f x
- , HMappable f xs
- , HList (HMap f xs)
- ) => HMappable f (HCons x xs) where
- type HMap f (HCons x xs) = HCons (Apply f x) (HMap f xs)
- hMap f (HCons x xs) = hCons (apply f x) (hMap f xs)
+instance ( ApplyT f x
+ , MapT f xs
+ , List (Map f xs)
+ ) => MapT f (Cons x xs) where
+ type Map f (Cons x xs) = Cons (Apply f x) (Map f xs)
+ hMap f (Cons x xs) = hCons (apply f x) (hMap f xs)
+
+-- All
+type family All f l
+type instance All f Nil = True
+type instance All f (Cons x xs) = If (Apply f x) (All f xs) False
+
+-- Length
+type family Length l
+type instance Length Nil = D0
+type instance Length (Cons e l) = Succ (Length l)
+
+-- Fail
+class Fail a
+
+-- OccursMany (zero or more)
+class OccursMany e l where
+ hOccursMany :: l -> [e]
+
+instance OccursMany e Nil where
+ hOccursMany _ = []
+
+instance ( List l
+ , OccursMany e l
+ )
+ => OccursMany e (Cons e l)
+ where
+ hOccursMany (Cons e l) = e : hOccursMany l
+
+instance ( List l
+ , OccursMany e l
+ )
+ => OccursMany e (Cons e' l)
+ where
+ hOccursMany (Cons _ l) = hOccursMany l
+
+-- OccursMany1 (one or more)
+class OccursMany1 e l where
+ hOccursMany1 :: l -> [e]
+
+instance Fail (TypeNotFound e) => OccursMany1 e Nil where
+ hOccursMany1 _ = undefined
+
+instance ( List l
+ , OccursMany e l
+ )
+ => OccursMany1 e (Cons e l)
+ where
+ hOccursMany1 (Cons e l) = e : hOccursMany l
+
+instance ( List l
+ , OccursMany1 e l
+ )
+ => OccursMany1 e (Cons e' l)
+ where
+ hOccursMany1 (Cons _ l) = hOccursMany1 l
+
+-- OccursOpt (zero or one)
+class OccursOpt e l where
+ hOccursOpt :: l -> Maybe e
+
+instance OccursOpt e Nil where
+ hOccursOpt _ = Nothing
+
+instance OccursNot e l => OccursOpt e (Cons e l) where
+ hOccursOpt (Cons e _) = Just e
+
+instance OccursOpt e l => OccursOpt e (Cons e' l) where
+ hOccursOpt (Cons _ l) = hOccursOpt l
+
+-- Occurs (one)
+class Occurs e l where
+ hOccurs :: l -> e
+
+data TypeNotFound e
+
+instance Fail (TypeNotFound e) => Occurs e Nil
+ where
+ hOccurs = undefined
+
+instance ( List l
+ , OccursNot e l
+ )
+ => Occurs e (Cons e l)
+ where
+ hOccurs (Cons e _) = e
+
+instance ( List l
+ , Occurs e l
+ )
+ => Occurs e (Cons e' l)
+ where
+ hOccurs (Cons _ l) = hOccurs l
+
+-- OccursNot (zero)
+data TypeFound e
+class OccursNot e l
+instance OccursNot e Nil
+instance Fail (TypeFound e) => OccursNot e (Cons e l)
+instance OccursNot e l => OccursNot e (Cons e' l)
+
+-- NoDuplicates
+class NoDuplicates l
+instance NoDuplicates Nil
+instance OccursNot e l => NoDuplicates (Cons e l)
+
+{-
+{-
+"Strongly Typed Heterogeneous Collections"
+ — August 26, 2004
+ Oleg Kiselyov
+ Ralf Lämmel
+ Keean Schupke
+==========================
+9 By chance or by design?
+
+We will now discuss the issues surrounding the definition of type
+equality, inequality, and unification — and give implementations
+differing in simplicity, genericity, and portability.
+
+We define the class TypeEq x y b for type equality. The class relates
+two types x and y to the type HTrue in case the two types are equal;
+otherwise, the types are related to HFalse. We should point out
+however groundness issues. If TypeEq is to return HTrue, the types
+must be ground; TypeEq can return HFalse even for unground types,
+provided they are instantiated enough to determine that they are not
+equal. So, TypeEq is total for ground types, and partial for unground
+types. We also define the class TypeCast x y: a constraint that holds
+only if the two types x and y are unifiable. Regarding groundness of x
+and y, the class TypeCast is less restricted than TypeEq. That is,
+TypeCast x y succeeds even for unground types x and y in case they can
+be made equal through unification. TypeEq and TypeCast are related to
+each other as fol- lows. Whenever TypeEq succeeds with HTrue, TypeCast
+succeeds as well. Whenever TypeEq succeeds with HFalse, TypeCast
+fails. But for unground types, when TypeCast succeeds, TypeEq might
+fail. So the two complement each other for unground types. Also,
+TypeEq is a partial predicate, while TypeCast is a relation. That’s
+why both are useful.
+ -}
+class TypeEq x y b | x y -> b
+instance TypeEq x x True
+instance TypeCast False b =>
+ TypeEq x y b
+
+class TypeCast a b | a -> b, b -> a
+ where
+ typeCast :: a -> b
+
+class TypeCast' t a b | t a -> b, t b -> a
+ where
+ typeCast' :: t -> a -> b
+
+class TypeCast'' t a b | t a -> b, t b -> a
+ where
+ typeCast'' :: t -> a -> b
+
+instance TypeCast' () a b => TypeCast a b
+ where
+ typeCast x = typeCast' () x
+
+instance TypeCast'' t a b => TypeCast' t a b
+ where
+ typeCast' = typeCast''
+
+instance TypeCast'' () a a
+ where
+ typeCast'' _ x = x
+-}
\ No newline at end of file
projects / hs-rrdtool.git / blobdiff