<!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>Data.Dynamic</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="index.html">Contents</a></li><li><a href="doc-index.html">Index</a></li></ul><p class="caption">base-4.5.1.0: Basic libraries</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>libraries@haskell.org</td></tr><tr><th>Safe Haskell</th><td>Trustworthy</td></tr></table><p class="caption">Data.Dynamic</p></div><div id="table-of-contents"><p class="caption">Contents</p><ul><li><a href="#g:1">The <code>Dynamic</code> type
</a></li><li><a href="#g:2">Converting to and from <code>Dynamic</code>
</a></li><li><a href="#g:3">Applying functions of dynamic type
</a></li></ul></div><div id="description"><p class="caption">Description</p><div class="doc"><p>The Dynamic interface provides basic support for dynamic types.
</p><p>Operations for injecting values of arbitrary type into
a dynamically typed value, Dynamic, are provided, together
with operations for converting dynamic values into a concrete
(monomorphic) type.
</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">module <a href="Data-Typeable.html">Data.Typeable</a></li><li class="src short"><span class="keyword">data</span> <a href="#t:Dynamic">Dynamic</a> </li><li class="src short"><a href="#v:toDyn">toDyn</a> :: <a href="Data-Typeable-Internal.html#t:Typeable">Typeable</a> a => a -> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></li><li class="src short"><a href="#v:fromDyn">fromDyn</a> :: <a href="Data-Typeable-Internal.html#t:Typeable">Typeable</a> a => <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> a -> a</li><li class="src short"><a href="#v:fromDynamic">fromDynamic</a> :: <a href="Data-Typeable-Internal.html#t:Typeable">Typeable</a> a => <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Maybe.html#t:Maybe">Maybe</a> a</li><li class="src short"><a href="#v:dynApply">dynApply</a> :: <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Maybe.html#t:Maybe">Maybe</a> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></li><li class="src short"><a href="#v:dynApp">dynApp</a> :: <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></li><li class="src short"><a href="#v:dynTypeRep">dynTypeRep</a> :: <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Typeable-Internal.html#t:TypeRep">TypeRep</a></li></ul></div><div id="interface"><h1>Documentation</h1><div class="top"><p class="src">module <a href="Data-Typeable.html">Data.Typeable</a></p></div><h1 id="g:1">The <code>Dynamic</code> type
</h1><div class="top"><p class="src"><span class="keyword">data</span> <a name="t:Dynamic" class="def">Dynamic</a> </p><div class="doc"><p>A value of type <code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code> is an object encapsulated together with its type.
</p><p>A <code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code> may only represent a monomorphic value; an attempt to
create a value of type <code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code> from a polymorphically-typed
expression will result in an ambiguity error (see <code><a href="Data-Dynamic.html#v:toDyn">toDyn</a></code>).
</p><p><code><a href="Text-Show.html#t:Show">Show</a></code>ing a value of type <code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code> returns a pretty-printed representation
of the object's type; useful for debugging.
</p></div><div class="subs instances"><p id="control.i:Dynamic" class="caption collapser" onclick="toggleSection('i:Dynamic')">Instances</p><div id="section.i:Dynamic" class="show"><table><tr><td class="src"><a href="Text-Show.html#t:Show">Show</a> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Data-Typeable-Internal.html#t:Typeable">Typeable</a> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Control-Exception-Base.html#t:Exception">Exception</a> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></td><td class="doc empty"> </td></tr></table></div></div></div><h1 id="g:2">Converting to and from <code>Dynamic</code>
</h1><div class="top"><p class="src"><a name="v:toDyn" class="def">toDyn</a> :: <a href="Data-Typeable-Internal.html#t:Typeable">Typeable</a> a => a -> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></p><div class="doc"><p>Converts an arbitrary value into an object of type <code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code>.
</p><p>The type of the object must be an instance of <code><a href="Data-Typeable-Internal.html#t:Typeable">Typeable</a></code>, which
ensures that only monomorphically-typed objects may be converted to
<code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code>. To convert a polymorphic object into <code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code>, give it
a monomorphic type signature. For example:
</p><pre> toDyn (id :: Int -> Int)
</pre></div></div><div class="top"><p class="src"><a name="v:fromDyn" class="def">fromDyn</a></p><div class="subs arguments"><p class="caption">Arguments</p><table><tr><td class="src">:: <a href="Data-Typeable-Internal.html#t:Typeable">Typeable</a> a</td><td class="doc empty"> </td></tr><tr><td class="src">=> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></td><td class="doc"><p>the dynamically-typed object
</p></td></tr><tr><td class="src">-> a</td><td class="doc"><p>a default value
</p></td></tr><tr><td class="src">-> a</td><td class="doc"><p>returns: the value of the first argument, if
it has the correct type, otherwise the value of
the second argument.
</p></td></tr></table></div><div class="doc"><p>Converts a <code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code> object back into an ordinary Haskell value of
the correct type. See also <code><a href="Data-Dynamic.html#v:fromDynamic">fromDynamic</a></code>.
</p></div></div><div class="top"><p class="src"><a name="v:fromDynamic" class="def">fromDynamic</a></p><div class="subs arguments"><p class="caption">Arguments</p><table><tr><td class="src">:: <a href="Data-Typeable-Internal.html#t:Typeable">Typeable</a> a</td><td class="doc empty"> </td></tr><tr><td class="src">=> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></td><td class="doc"><p>the dynamically-typed object
</p></td></tr><tr><td class="src">-> <a href="Data-Maybe.html#t:Maybe">Maybe</a> a</td><td class="doc"><p>returns: <code><code><a href="Data-Maybe.html#v:Just">Just</a></code> a</code>, if the dynamically-typed
object has the correct type (and <code>a</code> is its value),
or <code><a href="Data-Maybe.html#v:Nothing">Nothing</a></code> otherwise.
</p></td></tr></table></div><div class="doc"><p>Converts a <code><a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></code> object back into an ordinary Haskell value of
the correct type. See also <code><a href="Data-Dynamic.html#v:fromDyn">fromDyn</a></code>.
</p></div></div><h1 id="g:3">Applying functions of dynamic type
</h1><div class="top"><p class="src"><a name="v:dynApply" class="def">dynApply</a> :: <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Maybe.html#t:Maybe">Maybe</a> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></p></div><div class="top"><p class="src"><a name="v:dynApp" class="def">dynApp</a> :: <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a></p></div><div class="top"><p class="src"><a name="v:dynTypeRep" class="def">dynTypeRep</a> :: <a href="Data-Dynamic.html#t:Dynamic">Dynamic</a> -> <a href="Data-Typeable-Internal.html#t:TypeRep">TypeRep</a></p></div></div></div><div id="footer"><p>Produced by <a href="http://www.haskell.org/haddock/">Haddock</a> version 2.11.0</p></div></body></html>
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