<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Control.Monad.IO.Class</title><link href="ocean.css" rel="stylesheet" type="text/css" title="Ocean" /><script src="haddock-util.js" type="text/javascript"></script><script type="text/javascript">//<![CDATA[
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</script></head><body><div id="package-header"><ul class="links" id="page-menu"><li><a href="src/Control-Monad-IO-Class.html">Source</a></li><li><a href="index.html">Contents</a></li><li><a href="doc-index.html">Index</a></li></ul><p class="caption">transformers-0.2.2.0: Concrete functor and monad transformers</p></div><div id="content"><div id="module-header"><table class="info"><tr><th>Portability</th><td>portable</td></tr><tr><th>Stability</th><td>experimental</td></tr><tr><th>Maintainer</th><td>ross@soi.city.ac.uk</td></tr></table><p class="caption">Control.Monad.IO.Class</p></div><div id="description"><p class="caption">Description</p><div class="doc"><p>Class of monads based on <code>IO</code>.
</p></div></div><div id="synopsis"><p id="control.syn" class="caption expander" onclick="toggleSection('syn')">Synopsis</p><ul id="section.syn" class="hide" onclick="toggleSection('syn')"><li class="src short"><span class="keyword">class</span> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Control-Monad.html#t:Monad">Monad</a> m => <a href="#t:MonadIO">MonadIO</a> m <span class="keyword">where</span><ul class="subs"><li><a href="#v:liftIO">liftIO</a> :: <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a -> m a</li></ul></li></ul></div><div id="interface"><h1>Documentation</h1><div class="top"><p class="src"><span class="keyword">class</span> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Control-Monad.html#t:Monad">Monad</a> m => <a name="t:MonadIO" class="def">MonadIO</a> m <span class="keyword">where</span><a href="src/Control-Monad-IO-Class.html#MonadIO" class="link">Source</a></p><div class="doc"><p>Monads in which <code><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a></code> computations may be embedded.
Any monad built by applying a sequence of monad transformers to the
<code><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a></code> monad will be an instance of this class.
</p><p>Instances should satisfy the following laws, which state that <code><a href="Control-Monad-IO-Class.html#v:liftIO">liftIO</a></code>
is a transformer of monads:
</p><ul><li><pre><code><a href="Control-Monad-IO-Class.html#v:liftIO">liftIO</a></code> . <code><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Control-Monad.html#v:return">return</a></code> = <code><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Control-Monad.html#v:return">return</a></code></pre></li><li><pre><code><a href="Control-Monad-IO-Class.html#v:liftIO">liftIO</a></code> (m >>= f) = <code><a href="Control-Monad-IO-Class.html#v:liftIO">liftIO</a></code> m >>= (<code><a href="Control-Monad-IO-Class.html#v:liftIO">liftIO</a></code> . f)</pre></li></ul></div><div class="subs methods"><p class="caption">Methods</p><p class="src"><a name="v:liftIO" class="def">liftIO</a> :: <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a -> m a<a href="src/Control-Monad-IO-Class.html#liftIO" class="link">Source</a></p><div class="doc"><p>Lift a computation from the <code><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a></code> monad.
</p></div></div><div class="subs instances"><p id="control.i:MonadIO" class="caption collapser" onclick="toggleSection('i:MonadIO')">Instances</p><div id="section.i:MonadIO" class="show"><table><tr><td class="src"><a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-Identity.html#t:IdentityT">IdentityT</a> m)</td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-List.html#t:ListT">ListT</a> m)</td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-Maybe.html#t:MaybeT">MaybeT</a> m)</td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-Cont.html#t:ContT">ContT</a> r m)</td><td class="doc empty"> </td></tr><tr><td class="src">(<a href="Control-Monad-Trans-Error.html#t:Error">Error</a> e, <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m) => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-Error.html#t:ErrorT">ErrorT</a> e m)</td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-Reader.html#t:ReaderT">ReaderT</a> r m)</td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-State-Lazy.html#t:StateT">StateT</a> s m)</td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-State-Strict.html#t:StateT">StateT</a> s m)</td><td class="doc empty"> </td></tr><tr><td class="src">(<a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Data-Monoid.html#t:Monoid">Monoid</a> w, <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m) => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-Writer-Lazy.html#t:WriterT">WriterT</a> w m)</td><td class="doc empty"> </td></tr><tr><td class="src">(<a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Data-Monoid.html#t:Monoid">Monoid</a> w, <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m) => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-Writer-Strict.html#t:WriterT">WriterT</a> w m)</td><td class="doc empty"> </td></tr><tr><td class="src">(<a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Data-Monoid.html#t:Monoid">Monoid</a> w, <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m) => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-RWS-Lazy.html#t:RWST">RWST</a> r w s m)</td><td class="doc empty"> </td></tr><tr><td class="src">(<a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Data-Monoid.html#t:Monoid">Monoid</a> w, <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> m) => <a href="Control-Monad-IO-Class.html#t:MonadIO">MonadIO</a> (<a href="Control-Monad-Trans-RWS-Strict.html#t:RWST">RWST</a> r w s m)</td><td class="doc empty"> </td></tr></table></div></div></div></div></div><div id="footer"><p>Produced by <a href="http://www.haskell.org/haddock/">Haddock</a> version 2.9.2</p></div></body></html>
