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.

Minimal complete definition

foldl, foldr

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 CharStringLazy Char

FoldableLL CharString Char

FoldableLL [a] a

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.