diff --git a/ChangeLog.md b/ChangeLog.md --- a/ChangeLog.md +++ b/ChangeLog.md @@ -2,6 +2,25 @@ Change Log ========== +Version 0.8 (2016-07-17) *Constitution Day in South Korea* +---------------------------------------------------------- + +#### New features + +* Add pattern synonyms `Nil` and `Cons` for GHC >= 7.8 +* Add `Semigroup` instance for GHC >= 8 (base >= 4.9) +* Use inflexible instance for `IsString` to improve support for overloaded + strings ([Baldur Blöndal](https://github.com/Icelandjack)) + +#### Package changes + +* Change QuickCheck upper bound from 2.9 to 2.10 + +#### Development changes + +* Add `-Wall -Werror` testing +* Add testing for GHC 8.0.1 to Travis-CI + Version 0.7.1.2 (2015-08-23) *International Day for the Remembrance of the Slave Trade and its Abolition* --------------------------------------------------------------------------------------------------------- @@ -20,9 +39,10 @@ Version 0.7.1 (2014-06-28) *100th Anniversary of the Assassination of Franz Ferdinand* -------------------------------------------------------------------------------------- -#### Package changes +#### New features -* Add `IsList` instance for GHC >= 7.8 ([Icelandjack](https://github.com/Icelandjack)) +* Add `IsList` instance for GHC >= 7.8 + ([Baldur Blöndal](https://github.com/Icelandjack)) Version 0.7.0.1 (2014-03-24) *World Tuberculosis Day* ----------------------------------------------------- @@ -34,7 +54,7 @@ Version 0.7 (2014-03-17) *St. Patrick's Day* -------------------------------------------- -#### Package changes +#### New features * Add `NFData` instance (and `deepseq` dependency) * Add `IsString` instance diff --git a/Data/DList.hs b/Data/DList.hs --- a/Data/DList.hs +++ b/Data/DList.hs @@ -1,16 +1,16 @@ {-# OPTIONS_GHC -O2 #-} {-# OPTIONS_HADDOCK prune #-} {-# LANGUAGE CPP #-} -{-# LANGUAGE FlexibleInstances #-} +{-# LANGUAGE TypeFamilies #-} -- For the IsList and IsString instances + #if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 708 --- For the IsList instance: -{-# LANGUAGE TypeFamilies #-} +{-# LANGUAGE PatternSynonyms, ViewPatterns #-} #endif ----------------------------------------------------------------------------- -- | -- Module : Data.DList --- Copyright : (c) 2006-2009 Don Stewart, 2013-2014 Sean Leather +-- Copyright : (c) 2006-2009 Don Stewart, 2013-2016 Sean Leather -- License : See LICENSE file -- -- Maintainer : sean.leather@gmail.com @@ -21,30 +21,40 @@ -- ----------------------------------------------------------------------------- -module Data.DList ( +module Data.DList - DList +#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 800 + ( DList(Nil, Cons) +#else + ( DList +#endif -- * Construction - ,fromList -- :: [a] -> DList a - ,toList -- :: DList a -> [a] - ,apply -- :: DList a -> [a] -> [a] + , fromList + , toList + , apply -- * Basic functions - ,empty -- :: DList a - ,singleton -- :: a -> DList a - ,cons -- :: a -> DList a -> DList a - ,snoc -- :: DList a -> a -> DList a - ,append -- :: DList a -> DList a -> DList a - ,concat -- :: [DList a] -> DList a - ,replicate -- :: Int -> a -> DList a - ,list -- :: b -> (a -> DList a -> b) -> DList a -> b - ,head -- :: DList a -> a - ,tail -- :: DList a -> DList a - ,unfoldr -- :: (b -> Maybe (a, b)) -> b -> DList a - ,foldr -- :: (a -> b -> b) -> b -> DList a -> b - ,map -- :: (a -> b) -> DList a -> DList b + , empty + , singleton + , cons + , snoc + , append + , concat + , replicate + , list + , head + , tail + , unfoldr + , foldr + , map +#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 708 && __GLASGOW_HASKELL__ < 800 + -- * Pattern Synonyms + , pattern Nil + , pattern Cons +#endif + ) where import Prelude hiding (concat, foldr, map, head, tail, replicate) @@ -62,6 +72,10 @@ import Control.Applicative(Applicative(..)) #endif +#if MIN_VERSION_base(4,9,0) +import Data.Semigroup (Semigroup(..)) +#endif + #ifdef __GLASGOW_HASKELL__ import Text.Read (Lexeme(Ident), lexP, parens, prec, readPrec, readListPrec, @@ -111,6 +125,22 @@ toList = ($[]) . unDL {-# INLINE toList #-} +#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 708 +-- | A unidirectional pattern synonym using 'toList' in a view pattern and +-- matching on @[]@ +#if __GLASGOW_HASKELL__ >= 710 +pattern Nil :: DList a +#endif +pattern Nil <- (toList -> []) + +-- | A unidirectional pattern synonym using 'toList' in a view pattern and +-- matching on @x:xs@ such that you have the pattern @Cons x xs@ +#if __GLASGOW_HASKELL__ >= 710 +pattern Cons :: a -> [a] -> DList a +#endif +pattern Cons x xs <- (toList -> x:xs) +#endif + -- | Apply a dlist to a list to get the underlying list with an extension -- -- > apply (fromList xs) ys = xs ++ ys @@ -223,7 +253,8 @@ {-# INLINE fmap #-} instance Applicative DList where - pure = return + pure = singleton + {-# INLINE pure #-} (<*>) = ap instance Alternative DList where @@ -240,7 +271,7 @@ = foldr (append . k) empty m {-# INLINE (>>=) #-} - return x = singleton x + return = pure {-# INLINE return #-} fail _ = empty @@ -283,7 +314,11 @@ rnf = rnf . toList {-# INLINE rnf #-} -instance IsString (DList Char) where +-- This is _not_ a flexible instance to allow certain uses of overloaded +-- strings. See tests/OverloadedStrings.hs for an example and +-- https://git.haskell.org/ghc.git/commitdiff/b225b234a6b11e42fef433dcd5d2a38bb4b466bf +-- for the same change made to the IsString instance for lists. +instance a ~ Char => IsString (DList a) where fromString = fromList {-# INLINE fromString #-} @@ -296,3 +331,14 @@ {-# INLINE toList #-} #endif +#if MIN_VERSION_base(4,9,0) +instance Semigroup (DList a) where + (<>) = append + {-# INLINE (<>) #-} + stimes n x + | n < 0 = error "Data.DList.stimes: negative multiplier" + | otherwise = rep n + where + rep 0 = empty + rep i = x <> rep (pred i) +#endif diff --git a/LICENSE b/LICENSE --- a/LICENSE +++ b/LICENSE @@ -1,4 +1,4 @@ -Copyright (c) 2006-2009 Don Stewart, 2013-2014 Sean Leather +Copyright (c) 2006-2009 Don Stewart, 2013-2016 Sean Leather All rights reserved. diff --git a/README.md b/README.md --- a/README.md +++ b/README.md @@ -1,6 +1,59 @@ +# Difference Lists in Haskell + [![Build Status](https://travis-ci.org/spl/dlist.png?branch=master)](https://travis-ci.org/spl/dlist) [![Hackage](https://budueba.com/hackage/dlist)](https://hackage.haskell.org/package/dlist) +## Summary + The Haskell `dlist` package defines a list-like type supporting O(1) append and snoc operations. -See the [ChangeLog.md](https://github.com/spl/dlist/blob/master/ChangeLog.md) file for recent changes. +See [ChangeLog.md](./ChangeLog.md) for recent changes. + +## References + +### Research + +1. A novel representation of lists and its application to the function + “reverse.” John Hughes. Information Processing Letters. Volume 22, Issue 3. + 1986-03. Pages 141-144. + [[PDF](http://www.cs.tufts.edu/~nr/cs257/archive/john-hughes/lists.pdf)] + + This is the original source for a representation of lists as first-class functions. + +### Basic Introduction + +1. [Difference list](https://en.wikipedia.org/wiki/Difference_list). Wikipedia. + +2. [Difference lists](https://wiki.haskell.org/Difference_list). Haskell.org Wiki. + +3. [What is a DList?](https://stackoverflow.com/questions/3352418/what-is-a-dlist). + Stack Overflow. + +### Blogs and Discussion + +1. [Using Difference Lists](http://logicaltypes.blogspot.com/2008/08/using-difference-lists.html). + Douglas M. Auclair. 2008-08-13. + +2. [A Sort of Difference](https://archive.is/20140131124629/http://web.archive.org/web/20080918101635/comonad.com/reader/2008/a-sort-of-difference/). + Edward Kmett. 2008-09-18. + +3. [Reference for technique wanted](http://thread.gmane.org/gmane.comp.lang.haskell.cafe/82827). + Richard O'Keefe, et al. 2010-10-31. + +4. [24 Days of Hackage: dlist](https://ocharles.org.uk/blog/posts/2012-12-14-24-days-of-hackage-dlist.html). + Oliver Charles. 2012-12-14. + +5. [Constructing a list in a Monad](https://www.joachim-breitner.de/blog/620-Constructing_a_list_in_a_Monad). + Joachim Breitner. 2013-11-13. + +6. [Demystifying DList](http://h2.jaguarpaw.co.uk/posts/demystifying-dlist/). + ([On Reddit](https://www.reddit.com/r/haskell/comments/1w5duf/demystifying_dlist/)). + Tom Ellis. 2014-01-24. + +7. [keepEquals with Difference Lists](http://logicaltypes.blogspot.com/2014/06/keepequals-with-difference-lists.html), + Douglas M. Auclair. 2014-06-21. + +### Books + +1. [Chapter 13. Data Structures](http://book.realworldhaskell.org/read/data-structures.html). + Real World Haskell. 2008-12-05. diff --git a/dlist.cabal b/dlist.cabal --- a/dlist.cabal +++ b/dlist.cabal @@ -1,5 +1,5 @@ name: dlist -version: 0.7.1.2 +version: 0.8 synopsis: Difference lists description: Difference lists are a list-like type supporting O(1) append. This is @@ -10,19 +10,20 @@ license-file: LICENSE author: Don Stewart maintainer: Sean Leather -copyright: 2006-2009 Don Stewart, 2013-2014 Sean Leather +copyright: 2006-2009 Don Stewart, 2013-2016 Sean Leather homepage: https://github.com/spl/dlist bug-reports: https://github.com/spl/dlist/issues extra-source-files: README.md, ChangeLog.md build-type: Simple cabal-version: >= 1.9.2 -tested-with: GHC==7.0.4, - GHC==7.2.2, - GHC==7.4.2, - GHC==7.6.3, - GHC==7.8.4, - GHC==7.10.2 +tested-with: GHC==7.0.4 + GHC==7.2.2 + GHC==7.4.2 + GHC==7.6.3 + GHC==7.8.4 + GHC==7.10.3 + GHC==8.0.1 source-repository head type: git @@ -32,9 +33,9 @@ build-depends: base >= 4 && < 5, deepseq >= 1.1 && < 2 - ghc-options: -Wall extensions: CPP exposed-modules: Data.DList + ghc-options: -Wall test-suite test type: exitcode-stdio-1.0 @@ -43,4 +44,5 @@ build-depends: dlist, base, Cabal, - QuickCheck >= 2.7 && < 2.9 + QuickCheck >= 2.7 && < 2.10 + ghc-options: -Wall diff --git a/tests/Main.hs b/tests/Main.hs --- a/tests/Main.hs +++ b/tests/Main.hs @@ -1,10 +1,13 @@ {-# OPTIONS_GHC -Wall #-} {-# LANGUAGE CPP #-} #if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 708 --- For the IsList test: -{-# LANGUAGE OverloadedLists #-} +{-# LANGUAGE OverloadedLists #-} -- For the IsList test +#if __GLASGOW_HASKELL__ == 708 +{-# LANGUAGE PatternSynonyms #-} -- For pattern synonym use only in GHC 7.8 #endif +#endif + -------------------------------------------------------------------------------- module Main (main) where @@ -18,6 +21,13 @@ import Data.DList +import OverloadedStrings (testOverloadedStrings) + +#if MIN_VERSION_base(4,9,0) +import Data.Semigroup (Semigroup(..)) +import Data.List.NonEmpty (NonEmpty(..)) +#endif + -------------------------------------------------------------------------------- eqWith :: Eq b => (a -> b) -> (a -> b) -> a -> Bool @@ -92,35 +102,59 @@ test_fromList x = x == fromList [1,2,3] test_toList [1,2,3] = True test_toList _ = False + +prop_patterns :: [Int] -> Bool +prop_patterns xs = case fromList xs of + Nil -> xs == [] + Cons y ys -> xs == (y:ys) + _ -> False #endif +#if MIN_VERSION_base(4,9,0) +prop_Semigroup_append :: [Int] -> [Int] -> Bool +prop_Semigroup_append xs ys = xs <> ys == toList (fromList xs <> fromList ys) + +prop_Semigroup_sconcat :: NonEmpty [Int] -> Bool +prop_Semigroup_sconcat xs = sconcat xs == toList (sconcat (fmap fromList xs)) + +prop_Semigroup_stimes :: Int -> [Int] -> Bool +prop_Semigroup_stimes n xs = stimes n xs == toList (stimes n (fromList xs)) +#endif + -------------------------------------------------------------------------------- props :: [(String, Property)] props = - [ ("model", property prop_model) - , ("empty", property prop_empty) - , ("singleton", property prop_singleton) - , ("cons", property prop_cons) - , ("snoc", property prop_snoc) - , ("append", property prop_append) - , ("concat", property prop_concat) - , ("replicate", property prop_replicate) - , ("head", property prop_head) - , ("tail", property prop_tail) - , ("unfoldr", property prop_unfoldr) - , ("foldr", property prop_foldr) - , ("map", property prop_map) - , ("map fusion", property (prop_map_fusion (+1) (+1))) - , ("read . show", property prop_show_read) - , ("show . read", property prop_read_show) + [ ("model", property prop_model) + , ("empty", property prop_empty) + , ("singleton", property prop_singleton) + , ("cons", property prop_cons) + , ("snoc", property prop_snoc) + , ("append", property prop_append) + , ("concat", property prop_concat) + , ("replicate", property prop_replicate) + , ("head", property prop_head) + , ("tail", property prop_tail) + , ("unfoldr", property prop_unfoldr) + , ("foldr", property prop_foldr) + , ("map", property prop_map) + , ("map fusion", property (prop_map_fusion (+1) (+1))) + , ("read . show", property prop_show_read) + , ("show . read", property prop_read_show) #if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 708 - , ("IsList", property prop_IsList) + , ("IsList", property prop_IsList) + , ("patterns", property prop_patterns) #endif +#if MIN_VERSION_base(4,9,0) + , ("Semigroup <>", property prop_Semigroup_append) + , ("Semigroup sconcat", property prop_Semigroup_sconcat) + , ("Semigroup stimes", property prop_Semigroup_stimes) +#endif ] -------------------------------------------------------------------------------- main :: IO () -main = quickCheck $ conjoin $ List.map (uncurry label) props - +main = do + testOverloadedStrings + quickCheck $ conjoin $ List.map (uncurry label) props