map : (a -> b) -> List a -> List bApply a function to every element of a list, keeping the order. map f [1, 2, 3] = [f 1, f 2, f 3]
PréludeChargé par défaut — aucun
import nécessaire.List operations
Synopsis
map : (a -> b) -> List a -> List bfoldr : (a -> b -> b) -> b -> List a -> bfoldrLazy : (a -> Lazy b -> b) -> Lazy b -> List a -> bfoldl : (b -> a -> b) -> b -> List a -> breverse : List a -> List alength : List a -> NatisEmpty : List a -> Boolhead : List a -> Maybe atail : List a -> Maybe (List a)filter : (a -> Bool) -> List a -> List asplitAt : Nat -> List a -> (List a, List a)length : String -> Nat
foldr : (a -> b -> b) -> b -> List a -> bfoldrLazy : (a -> Lazy b -> b) -> Lazy b -> List a -> bRight fold that can stop: f receives the fold of the rest suspended (Lazy b) and computes it only if it reads it; the seed z is read only if the fold reaches the end. foldrLazy (\x rest -> p x || rest) False xs stops at the first p x.
foldl : (b -> a -> b) -> b -> List a -> bLeft fold: accumulate from the left. foldl f z [a, b, c] = f (f (f z a) b) c Prefer foldl for sums/products (tail-recursive).
reverse : List a -> List aReverse a list.
length : List a -> NatNumber of elements in a list, as a Nat.
isEmpty : List a -> BoolIs the list empty?
head : List a -> Maybe aSafely get the first element (Nothing if empty).
tail : List a -> Maybe (List a)Safely get all but the first element (Nothing if empty).
filter : (a -> Bool) -> List a -> List aKeep only elements satisfying a predicate. filter even [1, 2, 3, 4] = [2, 4]
splitAt : Nat -> List a -> (List a, List a)Split a list after its first n elements: the prefix of length n (or the whole list if shorter) paired with the remainder, in a single pass. splitAt 2 [1, 2, 3, 4] = ([1, 2], [3, 4])
length : String -> NatNumber of characters in a string, as a Nat. A bare length works on both: length s on a String, length xs on a list.