Data.Type.Regex.ListUtils

Various auixiliary type families that operate on type-level lists. Cherry picked from Data.List and lifted to the type-level.

Documentation

type family Nub xs :: [k]

Analogous to Data.List.nub

Equations

Nub `[]` = `[]`

Nub (x : xs) = x : Nub (FilterOut x xs)

type family IsNull xs

Analogous to Data.List.null

Equations

IsNull `[]` = True

IsNull xs = False

type family FilterOut x xs :: [k]

Analogous to `Data.List.filter (/= x) xs`

Equations

FilterOut x `[]` = `[]`

FilterOut x (x : xs) = FilterOut x xs

FilterOut x (y : xs) = y : FilterOut x xs

type family Elem x xs

Analogous to Data.List.elem

Equations

Elem x `[]` = False

Elem x (x : xs) = True

Elem x (y : xs) = Elem x xs

type family xs ++ ys

Analogous to Data.List.++

Equations

`[]` ++ ys = ys

(x : xs) ++ ys = x : (xs ++ ys)