Type.Family.List

Convenient aliases and type families for working with type-level lists.

Documentation

type Ø = `[]`

type (:<) = (:) infixr 5

type Only a = `[a]`

Type-level singleton list.

type family as ++ bs :: [k] infixr 5

Appends two type-level lists.

Equations

Ø ++ bs = bs

(a :< as) ++ bs = a :< (as ++ bs)

type family as >: a :: [k] infixl 6

Type-level list snoc.

Equations

Ø >: a = Only a

(b :< as) >: a = b :< (as >: a)

type family Reverse as :: [k]

Equations

Reverse Ø = Ø

Reverse (a :< as) = Reverse as >: a

type family Init' a as :: [k]

Equations

Init' a Ø = Ø

Init' a (b :< as) = a :< Init' b as

type family Last' a as :: k

Equations

Last' a Ø = a

Last' a (b :< as) = Last' b as

type family ListC cs :: Constraint

Takes a type-level list of Constraints to a single Constraint, where ListC cs holds iff all elements of cs hold.

Equations

ListC Ø = ØC

ListC (c :< cs) = (c, ListC cs)

type family f <$> a :: [l] infixr 4

Map an (f :: k -> l) over a type-level list (as :: [k]), giving a list (bs :: [l]).

Equations

f <$> Ø = Ø

f <$> (a :< as) = f a :< (f <$> as)

type family f <&> a :: [l] infixl 5

Map a list of (fs :: [k -> l]) over a single (a :: k), giving a list (bs :: [l]).

Equations

Ø <&> a = Ø

(f :< fs) <&> a = f a :< (fs <&> a)

type family f <*> a :: [l] infixr 4

Equations

fs <*> Ø = Ø

fs <*> (a :< as) = (fs <&> a) ++ (fs <*> as)

(==) :: Eq a => a -> a -> Bool