Sophie: ghc-doc-0:6.10.4-1mdv2010.0 i586

ghc-doc-6.10.4-1mdv2010.0.i586.rpm

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>base-4.1.0.0: Basic libraries</TD
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>Debug.Trace</FONT
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><TD CLASS="infohead"
>Portability</TD
><TD CLASS="infoval"
>portable</TD
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><TR
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>Stability</TD
><TD CLASS="infoval"
>provisional</TD
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>Maintainer</TD
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>libraries@haskell.org</TD
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>Contents</B
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><A HREF="#1"
>Tracing
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>Description</TD
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>The <TT
><A HREF="Debug-Trace.html#v%3Atrace"
>trace</A
></TT
> function.
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>Synopsis</TD
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><TD CLASS="decl"
><A HREF="#v%3AputTraceMsg"
>putTraceMsg</A
> :: <A HREF="Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="System-IO.html#t%3AIO"
>IO</A
> <A HREF="../ghc-prim/GHC-Unit.html#t%3A%28%29"
>()</A
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><TD CLASS="decl"
><A HREF="#v%3Atrace"
>trace</A
> ::  <A HREF="Data-Char.html#t%3AString"
>String</A
> -&gt; a -&gt; a</TD
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><TD CLASS="decl"
><A HREF="#v%3AtraceShow"
>traceShow</A
> :: <A HREF="Text-Show.html#t%3AShow"
>Show</A
> a =&gt; a -&gt; b -&gt; b</TD
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>Tracing
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><TD CLASS="decl"
><A NAME="v:putTraceMsg"
><A NAME="v%3AputTraceMsg"
></A
></A
><B
>putTraceMsg</B
> :: <A HREF="Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="System-IO.html#t%3AIO"
>IO</A
> <A HREF="../ghc-prim/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
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><TT
><A HREF="Debug-Trace.html#v%3AputTraceMsg"
>putTraceMsg</A
></TT
> function outputs the trace message from IO monad.
 Usually the output stream is System.IO.stderr but if the function is called
 from Windows GUI application then the output will be directed to the Windows
 debug console.
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><A NAME="v:trace"
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><B
>trace</B
> ::  <A HREF="Data-Char.html#t%3AString"
>String</A
> -&gt; a -&gt; a</TD
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><TD CLASS="doc"
>When called, <TT
><A HREF="Debug-Trace.html#v%3Atrace"
>trace</A
></TT
> outputs the string in its first argument, before 
returning the second argument as its result. The <TT
><A HREF="Debug-Trace.html#v%3Atrace"
>trace</A
></TT
> function is not 
referentially transparent, and should only be used for debugging, or for 
monitoring execution. Some implementations of <TT
><A HREF="Debug-Trace.html#v%3Atrace"
>trace</A
></TT
> may decorate the string 
that's output to indicate that you're tracing. The function is implemented on
top of <TT
><A HREF="Debug-Trace.html#v%3AputTraceMsg"
>putTraceMsg</A
></TT
>.
</TD
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><TD CLASS="decl"
><A NAME="v:traceShow"
><A NAME="v%3AtraceShow"
></A
></A
><B
>traceShow</B
> :: <A HREF="Text-Show.html#t%3AShow"
>Show</A
> a =&gt; a -&gt; b -&gt; b</TD
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><TR
><TD CLASS="doc"
><P
>Like <TT
><A HREF="Debug-Trace.html#v%3Atrace"
>trace</A
></TT
>, but uses <TT
><A HREF="Text-Show.html#v%3Ashow"
>show</A
></TT
> on the argument to convert it to a <TT
><A HREF="Data-Char.html#t%3AString"
>String</A
></TT
>.
</P
><PRE
> traceShow = trace . show
</PRE
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