<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <!-- Generated by HsColour, http://www.cs.york.ac.uk/fp/darcs/hscolour/ --> <title>Data/STRef.hs</title> <link type='text/css' rel='stylesheet' href='hscolour.css' /> </head> <body> <pre><a name="line-1"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span> <a name="line-2"></a><span class='hs-comment'>-- |</span> <a name="line-3"></a><span class='hs-comment'>-- Module : Data.STRef</span> <a name="line-4"></a><span class='hs-comment'>-- Copyright : (c) The University of Glasgow 2001</span> <a name="line-5"></a><span class='hs-comment'>-- License : BSD-style (see the file libraries/base/LICENSE)</span> <a name="line-6"></a><span class='hs-comment'>-- </span> <a name="line-7"></a><span class='hs-comment'>-- Maintainer : libraries@haskell.org</span> <a name="line-8"></a><span class='hs-comment'>-- Stability : experimental</span> <a name="line-9"></a><span class='hs-comment'>-- Portability : non-portable (uses Control.Monad.ST)</span> <a name="line-10"></a><span class='hs-comment'>--</span> <a name="line-11"></a><span class='hs-comment'>-- Mutable references in the (strict) ST monad.</span> <a name="line-12"></a><span class='hs-comment'>--</span> <a name="line-13"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span> <a name="line-14"></a> <a name="line-15"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>STRef</span> <span class='hs-layout'>(</span> <a name="line-16"></a> <span class='hs-comment'>-- * STRefs</span> <a name="line-17"></a> <span class='hs-conid'>STRef</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- abstract, instance Eq</span> <a name="line-18"></a> <span class='hs-varid'>newSTRef</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- :: a -> ST s (STRef s a)</span> <a name="line-19"></a> <span class='hs-varid'>readSTRef</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- :: STRef s a -> ST s a</span> <a name="line-20"></a> <span class='hs-varid'>writeSTRef</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- :: STRef s a -> a -> ST s ()</span> <a name="line-21"></a> <span class='hs-varid'>modifySTRef</span> <span class='hs-comment'>-- :: STRef s a -> (a -> a) -> ST s ()</span> <a name="line-22"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span> <a name="line-23"></a> <a name="line-24"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span> <a name="line-25"></a> <a name="line-26"></a><span class='hs-cpp'>#ifdef __GLASGOW_HASKELL__</span> <a name="line-27"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>GHC</span><span class='hs-varop'>.</span><span class='hs-conid'>ST</span> <a name="line-28"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>GHC</span><span class='hs-varop'>.</span><span class='hs-conid'>STRef</span> <a name="line-29"></a><span class='hs-cpp'>#endif</span> <a name="line-30"></a> <a name="line-31"></a><span class='hs-cpp'>#ifdef __HUGS__</span> <a name="line-32"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Hugs</span><span class='hs-varop'>.</span><span class='hs-conid'>ST</span> <a name="line-33"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Typeable</span> <a name="line-34"></a> <a name="line-35"></a><span class='hs-cpp'>#include "Typeable.h"</span> <a name="line-36"></a><span class='hs-conid'>INSTANCE_TYPEABLE2</span><span class='hs-layout'>(</span><span class='hs-conid'>STRef</span><span class='hs-layout'>,</span><span class='hs-varid'>stRefTc</span><span class='hs-layout'>,</span><span class='hs-str'>"STRef"</span><span class='hs-layout'>)</span> <a name="line-37"></a><span class='hs-cpp'>#endif</span> <a name="line-38"></a> <a name="line-39"></a><a name="modifySTRef"></a><span class='hs-comment'>-- |Mutate the contents of an 'STRef'</span> <a name="line-40"></a><span class='hs-definition'>modifySTRef</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>STRef</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ST</span> <span class='hs-varid'>s</span> <span class='hs-conid'>()</span> <a name="line-41"></a><span class='hs-definition'>modifySTRef</span> <span class='hs-varid'>ref</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>writeSTRef</span> <span class='hs-varid'>ref</span> <span class='hs-varop'>.</span> <span class='hs-varid'>f</span> <span class='hs-varop'>=<<</span> <span class='hs-varid'>readSTRef</span> <span class='hs-varid'>ref</span> </pre></body> </html>