diff --git a/Data/List/Extras/LazyLength.hs b/Data/List/Extras/LazyLength.hs --- a/Data/List/Extras/LazyLength.hs +++ b/Data/List/Extras/LazyLength.hs @@ -3,15 +3,14 @@ -- longer suppresses the warnings for orphaned RULES. Hence -Werror -- will make things crash on those systems, and even if that's -- removed then -Wall will send up too many false positives which --- may disconcert users. So now this file is now running without --- linting. Eheu! -{-# OPTIONS_GHC -fwarn-tabs #-} +-- may disconcert users. +{-# OPTIONS_GHC -Wall -fwarn-tabs #-} --- We need this in order to ensure the rules are picked up -{-# OPTIONS_GHC -O2 -fglasgow-exts #-} +-- We would need this in order to ensure the rules are parsed. +-- OPTIONS_GHC -O2 -fglasgow-exts ---------------------------------------------------------------- --- ~ 2008.08.23 +-- ~ 2009.04.02 -- | -- Module : Data.List.Extras.LazyLength -- Copyright : Copyright (c) 2007--2008 wren ng thornton @@ -21,9 +20,7 @@ -- Portability : portable -- -- This module provides least-strict functions for getting a list's --- length and doing natural things with it. On GHC this module also --- uses rewrite rules to convert certain calls to 'length' into our --- least-strict versions. +-- length and doing natural things with it. -- -- The regular version of @length@ will traverse the entire spine -- of the list in order to return an answer. For comparing the @@ -37,13 +34,15 @@ -- of an answer which retains the proper semantics. An option for -- doing this is to return Peano integers which can be decremented -- as much as necessary and no further (i.e. at most one more than --- the bound). Of course, Peano integers are woefully inefficient --- and would wreck the cache and burn heap. This module provides --- functions with the same lazy effect as if we used Peano integers, --- but does so efficiently instead. +-- the bound). Of course, Peano integers are woefully inefficient. +-- This module provides functions with the same lazy effect but +-- does so efficiently instead. -- --- (For Peano integers see numbers:"Data.Number.Natural" or --- non-negative:"Numeric.NonNegative.Class".) +-- As of version 0.3.0 the GHC rules to automatically rewrite +-- certain calls to 'length' into our least-strict versions have +-- been /removed/ for more consistent and predictable semantics. +-- All clients should explicitly call these least-strict functions +-- if they want the least-strict behavior. ---------------------------------------------------------------- module Data.List.Extras.LazyLength @@ -54,9 +53,7 @@ ---------------------------------------------------------------- ---------------------------------------------------------------- -- | A variant of 'length' which is least-strict for comparing --- against a boundary length. This function is defined primarily --- for use by rewrite rules rather than for direct use (though it's --- fine for that too). +-- against a boundary length. -- -- @lengthBound@ is polymorphic in the return of the helper -- function so we can use 'compare' as well as '>', '>=', '==', @@ -76,7 +73,7 @@ go 0 (_:_) = cmp 0 1 go n' (_:xs') = (go $! n'-1) xs' -{-# RULES +{- bad RULES "lengthBound/(>)" forall n xs. n > length xs = lengthBound n (>) xs "lengthBound/(>=)" forall n xs. n >= length xs = lengthBound n (>=) xs @@ -95,7 +92,7 @@ "lengthBound\\(<)" forall n xs. length xs < n = lengthBound n (>) xs "lengthBound\\compare" forall n xs. compare (length xs) n = lengthBound n (flip compare) xs - #-} + -} ---------------------------------------------------------------- @@ -103,8 +100,7 @@ -- | A variant of 'length' which is least-strict for comparing -- the lengths of two lists. This is as strict as the length of the -- shorter list (which allows comparing an infinite list against a --- finite list). The function itself is trivial, but again it's --- designed primarily for rewrite rules. +-- finite list). -- -- If you're going to immediately follow this with a 'zip' function -- then see "Data.List.Extras.Pair" instead. @@ -116,7 +112,7 @@ lengthCompare (_:xs) (_:ys) = lengthCompare xs ys -{-# RULES +{- bad RULES "lengthCompare/(>)" forall xs ys. length xs > length ys = lengthCompare xs ys == GT @@ -133,7 +129,7 @@ "lengthCompare/compare" forall xs ys. compare (length xs) (length ys) = lengthCompare xs ys - #-} + -} ---------------------------------------------------------------- ----------------------------------------------------------- fin. diff --git a/Data/List/Extras/Pair.hs b/Data/List/Extras/Pair.hs --- a/Data/List/Extras/Pair.hs +++ b/Data/List/Extras/Pair.hs @@ -2,7 +2,7 @@ {-# OPTIONS_GHC -Wall -fwarn-tabs #-} ---------------------------------------------------------------- --- ~ 2008.08.12 +-- ~ 2009.04.02 -- | -- Module : Data.List.Extras.Pair -- Copyright : Copyright (c) 2007--2008 wren ng thornton @@ -101,8 +101,8 @@ -- | A safe version of 'zip' that uses a user-defined list homomorphism. -pairBy :: ((a,b) -> m (a,b) -> m (a,b)) -> m (a,b) - -> [a] -> [b] -> Maybe (m (a,b)) +pairBy :: ((a,b) -> d -> d) -> d + -> [a] -> [b] -> Maybe d pairBy = pairWithBy (,) diff --git a/LICENSE b/LICENSE --- a/LICENSE +++ b/LICENSE @@ -1,4 +1,4 @@ -Copyright (c) 2007--2008, wren ng thornton. +Copyright (c) 2007--2009, wren ng thornton. ALL RIGHTS RESERVED. Redistribution and use in source and binary forms, with or without diff --git a/list-extras.cabal b/list-extras.cabal --- a/list-extras.cabal +++ b/list-extras.cabal @@ -1,9 +1,9 @@ ---------------------------------------------------------------- --- wren ng thornton ~ 2008.10.12 +-- wren ng thornton ~ 2009.04.02 ---------------------------------------------------------------- Name: list-extras -Version: 0.2.2.1 +Version: 0.3.0 Cabal-Version: >= 1.2 Build-Type: Simple Stability: stable