{- Copyright (C) 2007 John Goerzen <jgoerzen@complete.org> All rights reserved. For license and copyright information, see the file COPYRIGHT -} {- | Module : Data.ListLike Copyright : Copyright (C) 2007 John Goerzen License : BSD3 Maintainer : David Fox <dsf@seereason.com>, Andreas Abel Stability : stable Portability: portable Generic operations over list-like structures Written by John Goerzen, jgoerzen\@complete.org Please start with the introduction at "Data.ListLike#intro". -} module Data.ListLike (-- * Introduction -- $intro -- * Creation & Basic Functions empty, singleton, cons, snoc, append, uncons, head, last, tail, init, null, length, -- * List transformations map, rigidMap, reverse, intersperse, -- ** Conversions toList, fromList, fromListLike, -- * Reducing lists (folds), from "FoldableLL" foldl, foldl', foldl1, foldr, foldr', foldr1, -- ** Special folds concat, concatMap, rigidConcatMap, and, or, any, all, sum, product, maximum, minimum, fold, foldMap, -- * Building lists -- ** Scans -- ** Accumulating maps -- ** Infinite lists iterate, repeat, replicate, cycle, -- ** Unfolding -- * Sublists -- ** Extracting sublists take, drop, splitAt, takeWhile, dropWhile, dropWhileEnd, span, break, group, inits, tails, -- ** Predicates isPrefixOf, isSuffixOf, isInfixOf, -- ** Modify based on predicate stripPrefix, stripSuffix, -- * Searching lists -- ** Searching by equality elem, notElem, -- ** Searching with a predicate find, filter, partition, -- * Indexing lists index, elemIndex, elemIndices, findIndex, findIndices, -- * Zipping and unzipping lists zip, zipWith, unzip, -- * Monadic Operations sequence, sequence_, mapM, rigidMapM, mapM_, -- * Input and Output ListLikeIO(..), -- * Special lists -- ** Strings toString, fromString, lines, words, show, fromStringLike, fromText, fromLazyText, -- ** \"Set\" operations nub, delete, deleteFirsts, union, intersect, -- ** Ordered lists sort, insert, -- * Generalized functions -- ** The \"By\" operations -- *** User-supplied equality (replacing an Eq context) nubBy, deleteBy, deleteFirstsBy, unionBy, intersectBy, groupBy, -- *** User-supplied comparison (replacing an Ord context) sortBy, insertBy, -- maximumBy, minimumBy, -- ** The \"generic\" operations genericLength, genericTake, genericDrop, genericSplitAt, -- genericIndex, genericReplicate, -- * Notes on specific instances -- ** Lists -- $noteslist -- ** Arrays -- $notesarray -- ** ByteStrings -- $notesbytestring Chars(..), CharString (..), CharStringLazy (..), -- * Base Typeclasses -- ** The ListLike class ListLike, ListOps, -- ** The FoldableLL class FoldableLL, -- ** The StringLike class StringLike, -- ** The InfiniteListLike class InfiniteListLike ) where import Prelude hiding (length, head, last, null, tail, map, filter, concat, any, lookup, init, all, foldl, foldr, foldl1, foldr1, maximum, minimum, iterate, span, break, takeWhile, dropWhile, {-dropWhileEnd,-} reverse, zip, zipWith, sequence, sequence_, mapM, mapM_, concatMap, and, or, sum, product, repeat, replicate, cycle, take, drop, splitAt, elem, notElem, unzip, lines, words, unlines, unwords, foldMap, show) import Data.ListLike.Base import Data.ListLike.Chars import Data.ListLike.CharString import Data.ListLike.FoldableLL import Data.ListLike.Instances () import Data.ListLike.DList () import Data.ListLike.FMList () import Data.ListLike.String import Data.ListLike.Utils import Data.ListLike.IO {- $intro #intro# Welcome to ListLike. This module provides abstractions over typical list operations. It is designed to let you freely interchange different ways to represent sequences of data. It works with lists, various types of ByteStrings, and much more. In this module, you'll find generic versions of most of the functions you're used to using in the "Prelude", "Data.List", and "System.IO". They carry the same names, too. Therefore, you'll want to be careful how you import the module. I suggest using: >import qualified Data.ListLike as LL Then, you can use LL.fold, LL.map, etc. to get the generic version of the functions you want. Alternatively, you can hide the other versions from Prelude and import specific generic functions from here, such as: >import Prelude hiding (map) >import Data.ListLike (map) The module "Data.ListLike" actually simply re-exports the items found in a number of its sub-modules. If you want a smaller subset of "Data.ListLike", look at the documentation for its sub-modules and import the relevant one. In most cases, functions here can act as drop-in replacements for their list-specific counterparts. They will use the same underlying implementations for lists, so there should be no performance difference. You can make your own types instances of 'ListLike' as well. For more details, see the notes for the 'ListLike' typeclass. -} {- $noteslist Functions for operating on regular lists almost all use the native implementations in "Data.List", "Prelude", or similar standard modules. The exceptions are: * 'mapM' uses the default 'ListLike' implementation * 'hGet' does not exist for 'String' in the Haskell modules. It is implemented in terms of "Data.ByteString.Lazy". * 'hGetNonBlocking' is the same way. -} {- $notesarray 'Data.Array.Array' is an instance of 'ListLike'. Here are some notes about it: * The index you use must be an integral * 'ListLike' functions that take an index always take a 0-based index for compatibility with other 'ListLike' instances. This is translated by the instance functions into the proper offset from the bounds in the Array. * 'ListLike' functions preserve the original Array index numbers when possible. Functions such as 'cons' will reduce the lower bound to do their job. 'snoc' and 'append' increase the upper bound. 'drop' raises the lower bound and 'take' lowers the upper bound. * Functions that change the length of the array by an amount not known in advance, such as 'filter', will generate a new array with the lower bound set to 0. Furthermore, these functions cannot operate on infinite lists because they must know their length in order to generate the array. 'hGetContents' and its friends will therefore require the entire file to be read into memory before processing is possible. * 'empty', 'singleton', and 'fromList' also generate an array with the lower bound set to 0. * Many of these functions will generate runtime exceptions if you have not assigned a value to every slot in the array. -} {- $notesbytestring Both strict and lazy ByteStreams can be used with 'ListLike'. ByteString ListLike instances operate on 'Word8' elements. This is because both Data.ByteString.ByteString and Data.ByteString.Char8.ByteString have the same underlying type. If you wish to use the Char8 representation, the newtype wrappers 'CharString' and 'CharStringLazy' are available. Most 'ListLike' operations map directly to ByteStream options. Notable exceptions: * 'map' uses the 'ListLike' implementation. 'rigidMap' is more efficient. The same goes for 'concatMap' vs. 'rigidConcatMap'. * 'isInfixOf', 'sequence', 'mapM' and similar monad operations, 'insert', 'union', 'intersect', 'sortBy', and similar functions are not implemented in 'ByteStream' and use a naive default implementation. * The lazy ByteStream module implements fewer funtions than the strict ByteStream module. In some cases, default implementations are used. In others, notably related to I\/O, the lazy ByteStreams are converted back and forth to strict ones as appropriate. -}