Data.ListLike.FoldableLL

Generic tools for data structures that can be folded.

Written by John Goerzen, [e-mail]

FoldableLL Class

class FoldableLL full item | full -> item where

This is the primary class for structures that are to be considered foldable. A minimum complete definition provides foldl and foldr.

Instances of FoldableLL can be folded, and can be many and varied.

These functions are used heavily in Data.ListLike.

Methods

foldl :: (a -> item -> a) -> a -> full -> a

Left-associative fold

foldl' :: (a -> item -> a) -> a -> full -> a

Strict version of foldl.

foldl1 :: (item -> item -> item) -> full -> item

A variant of foldl with no base case. Requires at least 1 list element.

foldr :: (item -> b -> b) -> b -> full -> b

Right-associative fold

foldr' :: (item -> b -> b) -> b -> full -> b

Strict version of foldr

foldr1 :: (item -> item -> item) -> full -> item

Like foldr, but with no starting value

Instances

FoldableLL ByteString Word8

FoldableLL ByteString Word8

FoldableLL Text Char

FoldableLL Text Char

FoldableLL CharStringLazy Char

FoldableLL CharString Char

FoldableLL [a] a

Vector v a => FoldableLL (v a) a

FoldableLL (Seq a) a

FoldableLL (Vector a) a

Unbox a => FoldableLL (Vector a) a

Storable a => FoldableLL (Vector a) a

Ix i => FoldableLL (Array i e) e

Utilities

fold :: (FoldableLL full item, Monoid item) => full -> item

Combine the elements of a structure using a monoid. fold = foldMap id

foldMap :: (FoldableLL full item, Monoid m) => (item -> m) -> full -> m

Map each element to a monoid, then combine the results

foldM :: (Monad m, FoldableLL full item) => (a -> item -> m a) -> a -> full -> m a

Monadic version of left fold, similar to foldM.

sequence_ :: (Monad m, FoldableLL full (m item)) => full -> m ()

Evaluate each action, ignoring the results. Same as mapM_ id.

mapM_ :: (Monad m, FoldableLL full item) => (item -> m b) -> full -> m ()

A map in monad space, discarding results.