{-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE UndecidableInstances #-} {-# LANGUAGE TypeInType #-} module Data.Diverse.Type where import Data.Diverse.Type.Internal import Data.Kind import GHC.TypeLits -- | Ensures that @x@ is a unique member of @xs@, and that 'natVal' can be used. type UniqueMember x xs = (Unique x xs, KnownNat (IndexOf x xs)) -- | Ensures that @x@ is a unique member of @xs@, and that 'natVal' can be used. type UniqueMemberAt n x xs = (Unique x xs, KnownNat n, n ~ IndexOf x xs) -- | Ensures that @x@ is a unique member of @xs@, and that 'natVal' can be used. type UniqueLabelMember l xs = (UniqueLabel l xs, KnownNat (IndexOf (KindAtLabel l xs) xs)) -- | Ensures that @x@ is a unique member of @xs@ if it exists, and that 'natVal' can be used. type MaybeUniqueMemberAt n x xs = (Unique x xs, KnownNat n, n ~ PositionOf x xs) -- | Ensures that @x@ is a member of @xs@ at @n@, and that 'natVal' can be used. type MemberAt n x xs = (KnownNat n, x ~ KindAtIndex n xs) -- | Ensures that @x@ is a member of @xs@ at @n@ if it exists, and that 'natVal' can be used. type MaybeMemberAt n x xs = (KnownNat n, KindAtPositionIs n x xs) -- | Ensures x is a unique member in @xs@ iff it exists in @ys@ type family UniqueIfExists ys x xs :: Constraint where UniqueIfExists '[] x xs = () UniqueIfExists (y ': ys) y xs = Unique y xs UniqueIfExists (y ': ys) x xs = UniqueIfExists ys x xs -- | Ensures that the type list contain unique types type IsDistinct (xs :: [k]) = IsDistinctImpl xs xs -- | Return the list of distinct types in a typelist type family Nub (xs :: [k]) :: [k] where Nub '[] = '[] Nub (x ': xs) = NubImpl xs x xs -- | Ensures that @x@ only ever appears once in @xs@ type Unique (x :: k) (xs :: [k]) = UniqueImpl xs x xs -- | Ensures that the @label@ in @tagged label v@ only ever appears once in @xs@. type UniqueLabel (l :: k1) (xs :: [k]) = UniqueLabelImpl xs l xs -- | Ensures that the @label@ list all 'UniqueLabel's type family UniqueLabels (ls :: [k1]) (xs :: [k]) :: Constraint where UniqueLabels '[] xs = () UniqueLabels (l ': ls) xs = (UniqueLabel l xs, UniqueLabels ls xs) -- | Get the first index of a type (Indexed by 0) -- Will result in type error if x doesn't exist in xs. type IndexOf (x :: k) (xs :: [k]) = IndexOfImpl xs x xs -- | Get the first index of a type (Indexed by 1) -- Will return 0 if x doesn't exists in xs. type PositionOf (x :: k) (xs :: [k]) = PositionOfImpl 0 x xs -- | Get the type at an index type KindAtIndex (n :: Nat) (xs :: [k]) = KindAtIndexImpl n xs n xs -- | Get the type at a label type KindAtLabel (l :: k1) (xs :: [k]) = KindAtLabelImpl l xs xs -- | It's actually ok for the position to be zero, but if it's not zero then the types must match type family KindAtPositionIs (n :: Nat) (x :: k) (xs :: [k]) :: Constraint where KindAtPositionIs 0 x xs = () KindAtPositionIs n x xs = (x ~ KindAtIndexImpl (n - 1) xs (n - 1) xs) -- | Get the types at an list of index type family KindsAtIndices (ns :: [Nat]) (xs :: [k]) :: [k] where KindsAtIndices '[] xs = '[] KindsAtIndices (n ': ns) xs = KindAtIndex n xs ': KindsAtIndices ns xs type family KindsAtLabels (ls :: [k1]) (xs :: [k]) :: [k] where KindsAtLabels '[] xs = '[] KindsAtLabels (l ': ls) xs = KindAtLabel l xs ': KindsAtLabels ls xs -- | The typelist @xs@ without first @x@. It is okay for @x@ not to exist in @xs@ type family Without (x :: k) (xs :: [k]) :: [k] where Without x '[] = '[] Without x (x ': xs) = xs Without x (y ': xs) = y ': Without x xs -- | The typelist @xs@ with the first @x@ replaced by @y@. It is okay for @x@ not to exist in @xs@ type Replace (x :: k) (y :: k) (xs :: [k]) = ReplaceImpl x y xs -- | The typelist @zs@ with the first @xs@ replaced by @ys@. -- @xs@ must be the same size as @ys@ type Replaces (xs :: [k]) (ys :: [k]) (zs :: [k]) = ReplacesImpl xs ys xs ys zs -- | The typelist @xs@ without the type at Nat @n@. @n@ must be within bounds of @xs@ type WithoutIndex (n :: Nat) (xs :: [k]) = WithoutIndexImpl n xs n xs -- | The typelist @xs@ without the type at Nat @n@ replaced by @y@. @n@ must be within bounds of @xs@ type ReplaceIndex (n :: Nat) (y :: k) (xs :: [k]) = ReplaceIndexImpl n xs n y xs -- | The typelist @xs@ replaced by @ys@ at the indices @ns@. @ns@ and @ys@ must be the same length. @ns@ must be within bounds of @xs@ type ReplacesIndex (ns :: [Nat]) (ys :: [k]) (xs :: [k]) = ReplacesIndexImpl 0 ns ys xs -- | Get the typelist without the 'Head' type type family Tail (xs :: [k]) :: [k] where Tail '[] = TypeError ('Text "Tail error: empty type list") Tail (x ': xs) = xs -- | Get the first type in a typelist type family Head (xs :: [k]) :: k where Head '[] = TypeError ('Text "Head error: empty type list") Head (x ': xs) = x -- | Get the last type in a typelist type family Last (xs :: [k]) :: k where Last '[] = TypeError ('Text "Last error: empty type list") Last (x ': x' ': xs) = Last (x' ': xs) Last '[x] = x -- | Ensures two typelists are the same length type SameLength (xs :: [k1]) (ys :: [k2]) = SameLengthImpl xs ys xs ys -- | Set complement. Returns the set of things in @xs@ that are not in @ys@. type family Complement (xs :: [k]) (ys :: [k]) :: [k] where Complement xs '[] = xs Complement xs (y ': ys) = Complement (Without y xs) ys -- | Returns a @xs@ appended with @ys@ type family Append (xs :: [k]) (ys :: [k]) :: [k] where Append '[] ys = ys Append (x ': xs) ys = x ': Append xs ys -- | Returns the typelist without the 'Last' type type family Init (xs :: [k]) :: [k] where Init '[] = TypeError ('Text "Init error: empty type list") Init '[x] = '[] Init (x ': xs) = x ': Init xs -- | Takes two lists which must be the same length and returns a list of corresponding pairs. type Zip (xs :: [k]) (ys :: [k]) = ZipImpl xs ys xs ys