Sophie: ghc-MissingH-devel-1.1.0.3-2.fc14 x86

ghc-MissingH-devel-1.1.0.3-2.fc14.x86_64.rpm

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<!--Rendered using the Haskell Html Library v0.2-->
<HTML
><HEAD
><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=UTF-8"
><TITLE
>System.IO.Utils</TITLE
><LINK HREF="haddock.css" REL="stylesheet" TYPE="text/css"
><SCRIPT SRC="haddock-util.js" TYPE="text/javascript"
></SCRIPT
><SCRIPT TYPE="text/javascript"
>window.onload = function () {setSynopsis("mini_System-IO-Utils.html")};</SCRIPT
></HEAD
><BODY
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="topbar"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD
><IMG SRC="haskell_icon.gif" WIDTH="16" HEIGHT="16" ALT=" "
></TD
><TD CLASS="title"
>MissingH-1.1.0.3: Large utility library</TD
><TD CLASS="topbut"
><A HREF="src/System-IO-Utils.html"
>Source code</A
></TD
><TD CLASS="topbut"
><A HREF="index.html"
>Contents</A
></TD
><TD CLASS="topbut"
><A HREF="doc-index.html"
>Index</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="modulebar"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD
><FONT SIZE="6"
>System.IO.Utils</FONT
></TD
><TD ALIGN="right"
><TABLE CLASS="narrow" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="infohead"
>Portability</TD
><TD CLASS="infoval"
>portable</TD
></TR
><TR
><TD CLASS="infohead"
>Stability</TD
><TD CLASS="infoval"
>provisional</TD
></TR
><TR
><TD CLASS="infohead"
>Maintainer</TD
><TD CLASS="infoval"
>John Goerzen &lt;jgoerzen@complete.org&gt;</TD
></TR
></TABLE
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="section4"
><B
>Contents</B
></TD
></TR
><TR
><TD
><DL
><DT
><A HREF="#1"
>Entire File Handle Utilities
</A
></DT
><DD
><DL
><DT
><A HREF="#2"
>Opened Handle Data Copying
</A
></DT
><DT
><A HREF="#3"
>Disk File Data Copying
</A
></DT
></DL
></DD
><DT
><A HREF="#4"
>Line Processing Utilities
</A
></DT
><DT
><A HREF="#5"
>Lazy Interaction
</A
></DT
><DD
><DL
><DT
><A HREF="#6"
>Character-based
</A
></DT
><DT
><A HREF="#7"
>Line-based
</A
></DT
><DT
><A HREF="#8"
>Misc. Lazy
</A
></DT
></DL
></DD
><DT
><A HREF="#9"
>Optimizations
</A
></DT
></DL
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
>Description</TD
></TR
><TR
><TD CLASS="doc"
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
>Synopsis</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A HREF="#v%3AhCopy"
>hCopy</A
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b) =&gt; a -&gt; b -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AhCopyProgress"
>hCopyProgress</A
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> c, <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Prelude.html#t%3AIntegral"
>Integral</A
> a) =&gt; b -&gt; c -&gt; (<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Prelude.html#t%3AInteger"
>Integer</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Bool.html#t%3ABool"
>Bool</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
>) -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Int.html#t%3AInt"
>Int</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Prelude.html#t%3AInteger"
>Integer</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AhLineCopy"
>hLineCopy</A
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b) =&gt; a -&gt; b -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AlineCopy"
>lineCopy</A
> :: <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AcopyFileLinesToFile"
>copyFileLinesToFile</A
> :: <A HREF="System-IO-HVFS.html#t%3AFilePath"
>FilePath</A
> -&gt; <A HREF="System-IO-HVFS.html#t%3AFilePath"
>FilePath</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AhPutStrLns"
>hPutStrLns</A
> :: <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a =&gt; a -&gt; [<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>] -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AhGetLines"
>hGetLines</A
> :: <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a =&gt; a -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> [<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>]</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AhInteract"
>hInteract</A
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b) =&gt; a -&gt; b -&gt; (<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>) -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AhLineInteract"
>hLineInteract</A
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b) =&gt; a -&gt; b -&gt; ([<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>] -&gt; [<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>]) -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AlineInteract"
>lineInteract</A
> :: ([<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>] -&gt; [<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>]) -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AlazyMapM"
>lazyMapM</A
> ::  (a -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> b) -&gt; [a] -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> [b]</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AoptimizeForBatch"
>optimizeForBatch</A
> :: <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AoptimizeForInteraction"
>optimizeForInteraction</A
> :: <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
><A NAME="1"
><A NAME="1"
>Entire File Handle Utilities
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section2"
><A NAME="2"
><A NAME="2"
>Opened Handle Data Copying
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:hCopy"
><A NAME="v%3AhCopy"
></A
></A
><B
>hCopy</B
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b) =&gt; a -&gt; b -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#hCopy"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
>Copies from one handle to another in raw mode (using
hGetContents).
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:hCopyProgress"
><A NAME="v%3AhCopyProgress"
></A
></A
><B
>hCopyProgress</B
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#hCopyProgress"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="arg"
>:: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> c, <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Prelude.html#t%3AIntegral"
>Integral</A
> a)</TD
><TD CLASS="rdoc"
></TD
></TR
><TR
><TD CLASS="arg"
>=&gt; b</TD
><TD CLASS="rdoc"
>Input handle
</TD
></TR
><TR
><TD CLASS="arg"
>-&gt; c</TD
><TD CLASS="rdoc"
>Output handle
</TD
></TR
><TR
><TD CLASS="arg"
>-&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Prelude.html#t%3AInteger"
>Integer</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Bool.html#t%3ABool"
>Bool</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="rdoc"
>Progress function -- the bool is always False unless this is the final call
</TD
></TR
><TR
><TD CLASS="arg"
>-&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Int.html#t%3AInt"
>Int</A
></TD
><TD CLASS="rdoc"
></TD
></TR
><TR
><TD CLASS="arg"
>-&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a</TD
><TD CLASS="rdoc"
></TD
></TR
><TR
><TD CLASS="arg"
>-&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Prelude.html#t%3AInteger"
>Integer</A
></TD
><TD CLASS="rdoc"
></TD
></TR
><TR
><TD CLASS="ndoc" COLSPAN="2"
>Copies from one handle to another in raw mode (using hGetContents).
Takes a function to provide progress updates to the user.
</TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:hLineCopy"
><A NAME="v%3AhLineCopy"
></A
></A
><B
>hLineCopy</B
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b) =&gt; a -&gt; b -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#hLineCopy"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Copies from one handle to another in text mode (with lines).
Like hBlockCopy, this implementation is nice:
</P
><PRE
> hLineCopy hin hout = hLineInteract hin hout id
</PRE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:lineCopy"
><A NAME="v%3AlineCopy"
></A
></A
><B
>lineCopy</B
> :: <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#lineCopy"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
>Copies from <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/GHC-IO-Handle-FD.html#v%3Astdin"
>stdin</A
></TT
> to <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/GHC-IO-Handle-FD.html#v%3Astdout"
>stdout</A
></TT
> using lines.  An alias for <TT
><A HREF="System-IO-Utils.html#v%3AhLineCopy"
>hLineCopy</A
></TT
>
over <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/GHC-IO-Handle-FD.html#v%3Astdin"
>stdin</A
></TT
> and <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/GHC-IO-Handle-FD.html#v%3Astdout"
>stdout</A
></TT
>. 
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section2"
><A NAME="3"
><A NAME="3"
>Disk File Data Copying
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:copyFileLinesToFile"
><A NAME="v%3AcopyFileLinesToFile"
></A
></A
><B
>copyFileLinesToFile</B
> :: <A HREF="System-IO-HVFS.html#t%3AFilePath"
>FilePath</A
> -&gt; <A HREF="System-IO-HVFS.html#t%3AFilePath"
>FilePath</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#copyFileLinesToFile"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Copies one filename to another in text mode.
</P
><P
>Please note that the Unix permission bits are set at a default; you may
need to adjust them after the copy yourself.
</P
><P
>This function is implemented using <TT
><A HREF="System-IO-Utils.html#v%3AhLineCopy"
>hLineCopy</A
></TT
> internally. 
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
><A NAME="4"
><A NAME="4"
>Line Processing Utilities
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:hPutStrLns"
><A NAME="v%3AhPutStrLns"
></A
></A
><B
>hPutStrLns</B
> :: <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a =&gt; a -&gt; [<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>] -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#hPutStrLns"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
>Given a list of strings, output a line containing each item, adding
newlines as appropriate.  The list is not expected to have newlines already.
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:hGetLines"
><A NAME="v%3AhGetLines"
></A
></A
><B
>hGetLines</B
> :: <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a =&gt; a -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> [<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>]</TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#hGetLines"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Given a handle, returns a list of all the lines in that handle.
Thanks to lazy evaluation, this list does not have to be read all at once.
</P
><P
>Combined with <TT
><A HREF="System-IO-Utils.html#v%3AhPutStrLns"
>hPutStrLns</A
></TT
>, this can make a powerful way to develop
filters.  See the <TT
><A HREF="System-IO-Utils.html#v%3AlineInteract"
>lineInteract</A
></TT
> function for more on that concept.
</P
><P
>Example:
</P
><PRE
> main = do
        l &lt;- hGetLines stdin
        hPutStrLns stdout $ filter (startswith &quot;1&quot;) l
</PRE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
><A NAME="5"
><A NAME="5"
>Lazy Interaction
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section2"
><A NAME="6"
><A NAME="6"
>Character-based
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:hInteract"
><A NAME="v%3AhInteract"
></A
></A
><B
>hInteract</B
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b) =&gt; a -&gt; b -&gt; (<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>) -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#hInteract"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
><P
>This is similar to the built-in <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#v%3Ainteract"
>interact</A
></TT
>, but works
on any handle, not just stdin and stdout.
</P
><P
>In other words:
</P
><PRE
> interact = hInteract stdin stdout
</PRE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section2"
><A NAME="7"
><A NAME="7"
>Line-based
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:hLineInteract"
><A NAME="v%3AhLineInteract"
></A
></A
><B
>hLineInteract</B
> :: (<A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> a, <A HREF="System-IO-HVIO.html#t%3AHVIO"
>HVIO</A
> b) =&gt; a -&gt; b -&gt; ([<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>] -&gt; [<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>]) -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#hLineInteract"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Line-based interaction over arbitrary handles.  This is similar
to wrapping hInteract with <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-List.html#v%3Alines"
>lines</A
></TT
> and <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-List.html#v%3Aunlines"
>unlines</A
></TT
>.
</P
><P
>One could view this function like this:
</P
><PRE
> hLineInteract finput foutput func =
     let newf = unlines . func . lines in
         hInteract finput foutput newf
</PRE
><P
>Though the actual implementation is this for efficiency:
</P
><PRE
> hLineInteract finput foutput func =
     do
     lines &lt;- hGetLines finput
     hPutStrLns foutput (func lines)
</PRE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:lineInteract"
><A NAME="v%3AlineInteract"
></A
></A
><B
>lineInteract</B
> :: ([<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>] -&gt; [<A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-Char.html#t%3AString"
>String</A
>]) -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#lineInteract"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Line-based interaction.  This is similar to wrapping your
interact functions with <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-List.html#v%3Alines"
>lines</A
></TT
> and <TT
><A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/Data-List.html#v%3Aunlines"
>unlines</A
></TT
>.  This equality holds:
</P
><PRE
> lineInteract = hLineInteract stdin stdout
</PRE
><P
>Here's an example:
</P
><PRE
> main = lineInteract (filter (startswith &quot;1&quot;))
</PRE
><P
>This will act as a simple version of grep -- all lines that start with 1
will be displayed; all others will be ignored.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section2"
><A NAME="8"
><A NAME="8"
>Misc. Lazy
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:lazyMapM"
><A NAME="v%3AlazyMapM"
></A
></A
><B
>lazyMapM</B
> ::  (a -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> b) -&gt; [a] -&gt; <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> [b]</TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#lazyMapM"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
>Applies a given function to every item in a list, and returns
the new list.  Unlike the system's mapM, items are evaluated lazily. 
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
><A NAME="9"
><A NAME="9"
>Optimizations
</A
></A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:optimizeForBatch"
><A NAME="v%3AoptimizeForBatch"
></A
></A
><B
>optimizeForBatch</B
> :: <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#optimizeForBatch"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
>Sets stdin and stdout to be block-buffered.  This can save a huge amount
of system resources since far fewer syscalls are made, and can make programs
run much faster. 
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="topdecl"
><TABLE CLASS="declbar"
><TR
><TD CLASS="declname"
><A NAME="v:optimizeForInteraction"
><A NAME="v%3AoptimizeForInteraction"
></A
></A
><B
>optimizeForInteraction</B
> :: <A HREF="/usr/share/doc/ghc/html/libraries/base-4.2.0.2/System-IO.html#t%3AIO"
>IO</A
> <A HREF="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
><TD CLASS="declbut"
><A HREF="src/System-IO-Utils.html#optimizeForInteraction"
>Source</A
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="doc"
>Sets stdin and stdout to be line-buffered.  This saves resources
on stdout, but not many on stdin, since it it still looking for newlines. 
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="botbar"
>Produced by <A HREF="http://www.haskell.org/haddock/"
>Haddock</A
> version 2.6.1</TD
></TR
></TABLE
></BODY
></HTML
>