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<!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.Edison.Seq</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/Data-Edison-Seq.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">EdisonAPI-1.2.1: A library of efficient, purely-functional data structures (API)</p></div><div id="content"><div id="module-header"><table class="info"><tr><th>Portability</th><td>GHC, Hugs (MPTC and FD)</td></tr><tr><th>Stability</th><td>stable</td></tr><tr><th>Maintainer</th><td>robdockins AT fastmail DOT fm</td></tr><tr><th>Safe Haskell</th><td>Safe-Infered</td></tr></table><p class="caption">Data.Edison.Seq</p></div><div id="table-of-contents"><p class="caption">Contents</p><ul><li><a href="#g:1">Superclass aliases
</a><ul><li><a href="#g:2">Functor aliases
</a></li><li><a href="#g:3">Monad aliases
</a></li><li><a href="#g:4">MonadPlus aliases
</a></li></ul></li><li><a href="#g:5">The Sequence class
</a></li></ul></div><div id="description"><p class="caption">Description</p><div class="doc"><p>The sequence abstraction is usually viewed as a hierarchy of ADTs
   including lists, queues, deques, catenable lists, etc. However, such
   a hierarchy is based on efficiency rather than functionality. For example,
   a list supports all the operations that a deque supports, even though
   some of the operations may be inefficient. Hence, in Edison, all sequence
   data structures are defined as instances of the single Sequence class:
</p><pre>   class (Functor s, MonadPlus s) =&gt; Sequence s</pre><p>All sequences are also instances of <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Functor">Functor</a></code>, <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a></code>, and <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:MonadPlus">MonadPlus</a></code>.
   In addition, all sequences are expected to be instances of <code>Eq</code>, <code>Show</code>,
   and <code>Read</code>, although this is not enforced.
</p><p>We follow the naming convention that every module implementing sequences
   defines a type constructor named <code>Seq</code>.
</p><p>For each method the &quot;default&quot; complexity is listed.  Individual
   implementations may differ for some methods.  The documentation for
   each implementation will list those methods for which the running time
   differs from these.
</p><p>A description of each Sequence function appears below.  In most cases
   psudeocode is also provided. Obviously, the psudeocode is illustrative only.
</p><p>Sequences are represented in psudecode between angle brackets:
</p><pre> &lt;x0,x1,x2...,xn-1&gt;
</pre><p>Such that <code>x0</code> is at the left (front) of the sequence and
   <code>xn-1</code> is at the right (rear) of the sequence.
</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"><a href="#v:map">map</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; (a -&gt; b) -&gt; s a -&gt; s b</li><li class="src short"><a href="#v:singleton">singleton</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; a -&gt; s a</li><li class="src short"><a href="#v:concatMap">concatMap</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; (a -&gt; s b) -&gt; s a -&gt; s b</li><li class="src short"><a href="#v:empty">empty</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; s a</li><li class="src short"><a href="#v:append">append</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; s a -&gt; s a -&gt; s a</li><li class="src short"><span class="keyword">class</span> (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Functor">Functor</a> s, <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:MonadPlus">MonadPlus</a> s) =&gt; <a href="#t:Sequence">Sequence</a> s  <span class="keyword">where</span><ul class="subs"><li><a href="#v:lcons">lcons</a> ::  a -&gt; s a -&gt; s a</li><li><a href="#v:rcons">rcons</a> ::  a -&gt; s a -&gt; s a</li><li><a href="#v:fromList">fromList</a> ::  [a] -&gt; s a</li><li><a href="#v:copy">copy</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; s a</li><li><a href="#v:lview">lview</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m (a, s a)</li><li><a href="#v:lhead">lhead</a> ::  s a -&gt; a</li><li><a href="#v:lheadM">lheadM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m a</li><li><a href="#v:ltail">ltail</a> ::  s a -&gt; s a</li><li><a href="#v:ltailM">ltailM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m (s a)</li><li><a href="#v:rview">rview</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m (a, s a)</li><li><a href="#v:rhead">rhead</a> ::  s a -&gt; a</li><li><a href="#v:rheadM">rheadM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m a</li><li><a href="#v:rtail">rtail</a> ::  s a -&gt; s a</li><li><a href="#v:rtailM">rtailM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m (s a)</li><li><a href="#v:null">null</a> ::  s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a></li><li><a href="#v:size">size</a> ::  s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a></li><li><a href="#v:toList">toList</a> ::  s a -&gt; [a]</li><li><a href="#v:concat">concat</a> ::  s (s a) -&gt; s a</li><li><a href="#v:reverse">reverse</a> ::  s a -&gt; s a</li><li><a href="#v:reverseOnto">reverseOnto</a> ::  s a -&gt; s a -&gt; s a</li><li><a href="#v:fold">fold</a> ::  (a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:fold-39-">fold'</a> ::  (a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:fold1">fold1</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a</li><li><a href="#v:fold1-39-">fold1'</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a</li><li><a href="#v:foldr">foldr</a> ::  (a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:foldr-39-">foldr'</a> ::  (a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:foldl">foldl</a> ::  (b -&gt; a -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:foldl-39-">foldl'</a> ::  (b -&gt; a -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:foldr1">foldr1</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a</li><li><a href="#v:foldr1-39-">foldr1'</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a</li><li><a href="#v:foldl1">foldl1</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a</li><li><a href="#v:foldl1-39-">foldl1'</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a</li><li><a href="#v:reducer">reducer</a> ::  (a -&gt; a -&gt; a) -&gt; a -&gt; s a -&gt; a</li><li><a href="#v:reducer-39-">reducer'</a> ::  (a -&gt; a -&gt; a) -&gt; a -&gt; s a -&gt; a</li><li><a href="#v:reducel">reducel</a> ::  (a -&gt; a -&gt; a) -&gt; a -&gt; s a -&gt; a</li><li><a href="#v:reducel-39-">reducel'</a> ::  (a -&gt; a -&gt; a) -&gt; a -&gt; s a -&gt; a</li><li><a href="#v:reduce1">reduce1</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a</li><li><a href="#v:reduce1-39-">reduce1'</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a</li><li><a href="#v:take">take</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; s a</li><li><a href="#v:drop">drop</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; s a</li><li><a href="#v:splitAt">splitAt</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; (s a, s a)</li><li><a href="#v:subseq">subseq</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; s a</li><li><a href="#v:filter">filter</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; s a</li><li><a href="#v:partition">partition</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; (s a, s a)</li><li><a href="#v:takeWhile">takeWhile</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; s a</li><li><a href="#v:dropWhile">dropWhile</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; s a</li><li><a href="#v:splitWhile">splitWhile</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; (s a, s a)</li><li><a href="#v:inBounds">inBounds</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a></li><li><a href="#v:lookup">lookup</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; a</li><li><a href="#v:lookupM">lookupM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; m a</li><li><a href="#v:lookupWithDefault">lookupWithDefault</a> ::  a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; a</li><li><a href="#v:update">update</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; s a -&gt; s a</li><li><a href="#v:adjust">adjust</a> ::  (a -&gt; a) -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; s a</li><li><a href="#v:mapWithIndex">mapWithIndex</a> ::  (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b) -&gt; s a -&gt; s b</li><li><a href="#v:foldrWithIndex">foldrWithIndex</a> ::  (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:foldrWithIndex-39-">foldrWithIndex'</a> ::  (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:foldlWithIndex">foldlWithIndex</a> ::  (b -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:foldlWithIndex-39-">foldlWithIndex'</a> ::  (b -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b) -&gt; b -&gt; s a -&gt; b</li><li><a href="#v:zip">zip</a> ::  s a -&gt; s b -&gt; s (a, b)</li><li><a href="#v:zip3">zip3</a> ::  s a -&gt; s b -&gt; s c -&gt; s (a, b, c)</li><li><a href="#v:zipWith">zipWith</a> ::  (a -&gt; b -&gt; c) -&gt; s a -&gt; s b -&gt; s c</li><li><a href="#v:zipWith3">zipWith3</a> ::  (a -&gt; b -&gt; c -&gt; d) -&gt; s a -&gt; s b -&gt; s c -&gt; s d</li><li><a href="#v:unzip">unzip</a> ::  s (a, b) -&gt; (s a, s b)</li><li><a href="#v:unzip3">unzip3</a> ::  s (a, b, c) -&gt; (s a, s b, s c)</li><li><a href="#v:unzipWith">unzipWith</a> ::  (a -&gt; b) -&gt; (a -&gt; c) -&gt; s a -&gt; (s b, s c)</li><li><a href="#v:unzipWith3">unzipWith3</a> ::  (a -&gt; b) -&gt; (a -&gt; c) -&gt; (a -&gt; d) -&gt; s a -&gt; (s b, s c, s d)</li><li><a href="#v:strict">strict</a> ::  s a -&gt; s a</li><li><a href="#v:strictWith">strictWith</a> ::  (a -&gt; b) -&gt; s a -&gt; s a</li><li><a href="#v:structuralInvariant">structuralInvariant</a> ::  s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a></li><li><a href="#v:instanceName">instanceName</a> ::  s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a></li></ul></li></ul></div><div id="interface"><h1 id="g:1">Superclass aliases
</h1><h2 id="g:2">Functor aliases
</h2><div class="top"><p class="src"><a name="v:map" class="def">map</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; (a -&gt; b) -&gt; s a -&gt; s b<a href="src/Data-Edison-Seq.html#map" class="link">Source</a></p><div class="doc"><p>Return the result of applying a function to
   every element of a sequence.  Identical
   to <code>fmap</code> from <code>Functor</code>.
</p><pre> map f &lt;x0,...,xn-1&gt; = &lt;f x0,...,f xn-1&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>map f empty = empty</pre></li><li><pre>map f (lcons x xs) = lcons (f x) (map f xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div></div><h2 id="g:3">Monad aliases
</h2><div class="top"><p class="src"><a name="v:singleton" class="def">singleton</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; a -&gt; s a<a href="src/Data-Edison-Seq.html#singleton" class="link">Source</a></p><div class="doc"><p>Create a singleton sequence.  Identical to <code>return</code>
   from <code>Monad</code>.
</p><pre> singleton x = &lt;x&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>singleton x = lcons x empty = rcons x empty</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div></div><div class="top"><p class="src"><a name="v:concatMap" class="def">concatMap</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; (a -&gt; s b) -&gt; s a -&gt; s b<a href="src/Data-Edison-Seq.html#concatMap" class="link">Source</a></p><div class="doc"><p>Apply a sequence-producing function to every element
   of a sequence and flatten the result. <code><a href="Data-Edison-Seq.html#v:concatMap">concatMap</a></code>
   is the bind <code>(&gt;&gt;=)</code> operation of from <code>Monad</code> with the
   arguments in the reverse order.
</p><pre> concatMap f xs = concat (map f xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>concatMap f xs = concat (map f xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n + m )</code>
     where <code>n</code> is the length of the input sequence, <code>m</code> is the
     length of the output sequence, and <code>t</code> is the running time of <code>f</code>
</p></div></div><h2 id="g:4">MonadPlus aliases
</h2><div class="top"><p class="src"><a name="v:empty" class="def">empty</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; s a<a href="src/Data-Edison-Seq.html#empty" class="link">Source</a></p><div class="doc"><p>The empty sequence.  Identical to <code>mzero</code>
   from <code>MonadPlus</code>.
</p><pre> empty = &lt;&gt;
</pre><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div></div><div class="top"><p class="src"><a name="v:append" class="def">append</a> :: <a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> s =&gt; s a -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#append" class="link">Source</a></p><div class="doc"><p>Append two sequence, with the first argument on the left
   and the second argument on the right.  Identical to <code>mplus</code>
   from <code>MonadPlus</code>.
</p><pre> append &lt;x0,...,xn-1&gt; &lt;y0,...,ym-1&gt; = &lt;x0,...,xn-1,y0,...,ym-1&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>append xs ys = foldr lcons ys xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n1 )</code>
</p></div></div><h1 id="g:5">The Sequence class
</h1><div class="top"><p class="src"><span class="keyword">class</span> (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Functor">Functor</a> s, <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:MonadPlus">MonadPlus</a> s) =&gt; <a name="t:Sequence" class="def">Sequence</a> s  <span class="keyword">where</span><a href="src/Data-Edison-Seq.html#Sequence" class="link">Source</a></p><div class="doc"><p>The <code><a href="Data-Edison-Seq.html#t:Sequence">Sequence</a></code> class defines an interface for datatypes which
   implement sequences.  A description for each function is
   given below.  
</p></div><div class="subs methods"><p class="caption">Methods</p><p class="src"><a name="v:lcons" class="def">lcons</a> ::  a -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#lcons" class="link">Source</a></p><div class="doc"><p>Add a new element to the front/left of a sequence
</p><pre> lcons x &lt;x0,...,xn-1&gt; = &lt;x,x0,...,xn-1&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>lcons x xs = append (singleton x) xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div><p class="src"><a name="v:rcons" class="def">rcons</a> ::  a -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#rcons" class="link">Source</a></p><div class="doc"><p>Add a new element to the right/rear of a sequence
</p><pre> rcons x &lt;x0,...,xn-1&gt; = &lt;x0,...,xn-1,x&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>rcons x xs = append xs (singleton x)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:fromList" class="def">fromList</a> ::  [a] -&gt; s a<a href="src/Data-Edison-Seq.html#fromList" class="link">Source</a></p><div class="doc"><p>Convert a list into a sequence
</p><pre> fromList [x0,...,xn-1] = &lt;x0,...,xn-1&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>fromList xs = foldr lcons empty xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:copy" class="def">copy</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; s a<a href="src/Data-Edison-Seq.html#copy" class="link">Source</a></p><div class="doc"><p>Create a sequence containing <code>n</code> copies of the given element.
   Return <code><a href="Data-Edison-Seq.html#v:empty">empty</a></code> if <code>n&lt;0</code>.
</p><pre>copy n x = &lt;x,...,x&gt;</pre><p><em>Axioms:</em>
</p><ul><li><pre>n &gt; 0    ==&gt; copy n x = cons x (copy (n-1) x)</pre></li><li><pre>n &lt;= 0   ==&gt; copy n x = empty</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:lview" class="def">lview</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m (a, s a)<a href="src/Data-Edison-Seq.html#lview" class="link">Source</a></p><div class="doc"><p>Separate a sequence into its first (leftmost) element and the
   remaining sequence.  Calls <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#v:fail">fail</a></code> if the sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>lview empty = fail</pre></li><li><pre>lview (lcons x xs) = return (x,xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div><p class="src"><a name="v:lhead" class="def">lhead</a> ::  s a -&gt; a<a href="src/Data-Edison-Seq.html#lhead" class="link">Source</a></p><div class="doc"><p>Return the first element of a sequence.
   Signals an error if the sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>lhead empty = undefined</pre></li><li><pre>lhead (lcons x xs) = x</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div><p class="src"><a name="v:lheadM" class="def">lheadM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m a<a href="src/Data-Edison-Seq.html#lheadM" class="link">Source</a></p><div class="doc"><p>Returns the first element of a sequence. 
   Calls <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#v:fail">fail</a></code> if the sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>lheadM empty = fail</pre></li><li><pre>lheadM (lcons x xs) = return x</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div><p class="src"><a name="v:ltail" class="def">ltail</a> ::  s a -&gt; s a<a href="src/Data-Edison-Seq.html#ltail" class="link">Source</a></p><div class="doc"><p>Delete the first element of the sequence.
   Signals error if sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>ltail empty = undefined</pre></li><li><pre>ltail (lcons x xs) = xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div><p class="src"><a name="v:ltailM" class="def">ltailM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m (s a)<a href="src/Data-Edison-Seq.html#ltailM" class="link">Source</a></p><div class="doc"><p>Delete the first element of the sequence.
   Calls <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#v:fail">fail</a></code> if the sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>ltailM empty = fail</pre></li><li><pre>ltailM (lcons x xs) = return xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div><p class="src"><a name="v:rview" class="def">rview</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m (a, s a)<a href="src/Data-Edison-Seq.html#rview" class="link">Source</a></p><div class="doc"><p>Separate a sequence into its last (rightmost) element and the
   remaining sequence.  Calls <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#v:fail">fail</a></code> if the sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>rview empty = fail</pre></li><li><pre>rview (rcons x xs) = return (x,xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:rhead" class="def">rhead</a> ::  s a -&gt; a<a href="src/Data-Edison-Seq.html#rhead" class="link">Source</a></p><div class="doc"><p>Return the last (rightmost) element of the sequence.
   Signals error if sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>rhead empty = undefined</pre></li><li><pre>rhead (rcons x xs) = x</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:rheadM" class="def">rheadM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m a<a href="src/Data-Edison-Seq.html#rheadM" class="link">Source</a></p><div class="doc"><p>Returns the last element of the sequence.
    Calls <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#v:fail">fail</a></code> if the sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>rheadM empty = fail</pre></li><li><pre>rheadM (rcons x xs) = return x</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:rtail" class="def">rtail</a> ::  s a -&gt; s a<a href="src/Data-Edison-Seq.html#rtail" class="link">Source</a></p><div class="doc"><p>Delete the last (rightmost) element of the sequence.
   Signals an error if the sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>rtail empty = undefined</pre></li><li><pre>rtail (rcons x xs) = xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:rtailM" class="def">rtailM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; s a -&gt; m (s a)<a href="src/Data-Edison-Seq.html#rtailM" class="link">Source</a></p><div class="doc"><p>Delete the last (rightmost) element of the sequence.
   Calls <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#v:fail">fail</a></code> of the sequence is empty
</p><p><em>Axioms:</em>
</p><ul><li><pre>rtailM empty = fail</pre></li><li><pre>rtailM (rcons x xs) = return xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:null" class="def">null</a> ::  s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a><a href="src/Data-Edison-Seq.html#null" class="link">Source</a></p><div class="doc"><p>Returns <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#v:True">True</a></code> if the sequence is empty and <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#v:False">False</a></code> otherwise.
</p><pre> null &lt;x0,...,xn-1&gt; = (n==0)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>null xs = (size xs == 0)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( 1 )</code>
</p></div><p class="src"><a name="v:size" class="def">size</a> ::  s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a><a href="src/Data-Edison-Seq.html#size" class="link">Source</a></p><div class="doc"><p>Returns the length of a sequence.
</p><pre> size &lt;x0,...,xn-1&gt; = n
</pre><p><em>Axioms:</em>
</p><ul><li><pre>size empty = 0</pre></li><li><pre>size (lcons x xs) = 1 + size xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:toList" class="def">toList</a> ::  s a -&gt; [a]<a href="src/Data-Edison-Seq.html#toList" class="link">Source</a></p><div class="doc"><p>Convert a sequence to a list.
</p><pre> toList &lt;x0,...,xn-1&gt; = [x0,...,xn-1]
</pre><p><em>Axioms:</em>
</p><ul><li><pre>toList empty = []</pre></li><li><pre>toList (lcons x xs) = x : toList xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:concat" class="def">concat</a> ::  s (s a) -&gt; s a<a href="src/Data-Edison-Seq.html#concat" class="link">Source</a></p><div class="doc"><p>Flatten a sequence of sequences into a simple sequence.
</p><pre> concat xss = foldr append empty xss
</pre><p><em>Axioms:</em>
</p><ul><li><pre>concat xss = foldr append empty xss</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n + m )</code>
    where <code>n</code> is the length of the input sequence and <code>m</code> is
    length of the output sequence.
</p></div><p class="src"><a name="v:reverse" class="def">reverse</a> ::  s a -&gt; s a<a href="src/Data-Edison-Seq.html#reverse" class="link">Source</a></p><div class="doc"><p>Reverse the order of a sequence
</p><pre> reverse &lt;x0,...,xn-1&gt; = &lt;xn-1,...,x0&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>reverse empty = empty</pre></li><li><pre>reverse (lcons x xs) = rcons x (reverse xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:reverseOnto" class="def">reverseOnto</a> ::  s a -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#reverseOnto" class="link">Source</a></p><div class="doc"><p>Reverse a sequence onto the front of another sequence.
</p><pre> reverseOnto &lt;x0,...,xn-1&gt; &lt;y0,...,ym-1&gt; = &lt;xn-1,...,x0,y0,...,ym-1&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>reverseOnto xs ys = append (reverse xs) ys</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n1 )</code>
</p></div><p class="src"><a name="v:fold" class="def">fold</a> ::  (a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#fold" class="link">Source</a></p><div class="doc"><p>Combine all the elements of a sequence into a single value,
   given a combining function and an initial value.  The order
   in which the elements are applied to the combining function
   is unspecified.  <code>fold</code> is one of the few ambiguous sequence
   functions.
</p><p><em>Axioms:</em>
</p><ul><li><pre>fold f c empty = c</pre></li><li><pre>f is fold-commutative ==&gt; fold f = foldr f = foldl f</pre></li></ul><p><code>fold f</code> is <em>unambiguous</em> iff <code>f</code> is fold-commutative.
</p><p>Default running type: <code>O( t * n )</code>
     where <code>t</code> is the running tome of <code>f</code>.
</p></div><p class="src"><a name="v:fold-39-" class="def">fold'</a> ::  (a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#fold%27" class="link">Source</a></p><div class="doc"><p>A strict variant of <code><a href="Data-Edison-Seq.html#v:fold">fold</a></code>.  <code>fold'</code> is one of the few ambiguous
   sequence functions.
</p><p><em>Axioms:</em>
</p><ul><li><pre>forall a. f a _|_ = _|_ ==&gt; fold f x xs = fold' f x xs</pre></li></ul><p><code>fold f</code> is <em>unambiguous</em> iff <code>f</code> is fold-commutative.
</p><p>Default running type: <code>O( t * n )</code>
     where <code>t</code> is the running tome of <code>f</code>.
</p></div><p class="src"><a name="v:fold1" class="def">fold1</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#fold1" class="link">Source</a></p><div class="doc"><p>Combine all the elements of a non-empty sequence into a
   single value, given a combining function. Signals an error
   if the sequence is empty.
</p><p><em>Axioms:</em>
</p><ul><li><pre>f is fold-commutative ==&gt; fold1 f = foldr1 f = foldl1 f</pre></li></ul><p><code>fold1 f</code> is <em>unambiguous</em> iff <code>f</code> is fold-commutative.
</p><p>Default running type: <code>O( t * n )</code>
     where <code>t</code> is the running tome of <code>f</code>.
</p></div><p class="src"><a name="v:fold1-39-" class="def">fold1'</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#fold1%27" class="link">Source</a></p><div class="doc"><p>A strict variant of <code><a href="Data-Edison-Seq.html#v:fold1">fold1</a></code>.
</p><p><em>Axioms:</em>
</p><ul><li><pre>forall a. f a _|_ = _|_ ==&gt; fold1' f xs = fold1 f xs</pre></li></ul><p><code>fold1' f</code> is <em>unambiguous</em> iff <code>f</code> is fold-commutative.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldr" class="def">foldr</a> ::  (a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#foldr" class="link">Source</a></p><div class="doc"><p>Combine all the elements of a sequence into a single value,
   given a combining function and an initial value.  The function
   is applied with right nesting.
</p><pre> foldr (%) c &lt;x0,...,xn-1&gt; = x0 % (x1 % ( ... % (xn-1 % c)))
</pre><p><em>Axioms:</em>
</p><ul><li><pre>foldr f c empty = c</pre></li><li><pre>foldr f c (lcons x xs) = f x (foldr f c xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldr-39-" class="def">foldr'</a> ::  (a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#foldr%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:foldr">foldr</a></code>.  
</p><p><em>Axioms:</em>
</p><ul><li><pre>forall a. f a _|_ = _|_ ==&gt; foldr f x xs = foldr' f x xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldl" class="def">foldl</a> ::  (b -&gt; a -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#foldl" class="link">Source</a></p><div class="doc"><p>Combine all the elements of a sequence into a single value,
   given a combining function and an initial value.  The function
   is applied with left nesting.
</p><pre> foldl (%) c &lt;x0,...,xn-1&gt; = (((c % x0) % x1) % ... ) % xn-1
</pre><p><em>Axioms:</em>
</p><ul><li><pre>foldl f c empty = c</pre></li><li><pre>foldl f c (lcons x xs) = foldl f (f c x) xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldl-39-" class="def">foldl'</a> ::  (b -&gt; a -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#foldl%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:foldl">foldl</a></code>.
</p><p><em>Axioms:</em>
</p><ul><li> forall a. f _|_ a = _|_ ==&gt; foldl f z xs = foldl' f z xs
</li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldr1" class="def">foldr1</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#foldr1" class="link">Source</a></p><div class="doc"><p>Combine all the elements of a non-empty sequence into a
   single value, given a combining function.  The function
   is applied with right nesting. Signals an error if the
   sequence is empty.
</p><pre> foldr1 (+) &lt;x0,...,xn-1&gt;
   | n==0 = error &quot;ModuleName.foldr1: empty sequence&quot;
   | n&gt;0  = x0 + (x1 + ... + xn-1)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>foldr1 f empty = undefined</pre></li><li><pre>foldr1 f (rcons x xs) = foldr f x xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldr1-39-" class="def">foldr1'</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#foldr1%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:foldr1">foldr1</a></code>.
</p><p><em>Axioms:</em>
</p><ul><li> forall a. f a _|_ = _|_ ==&gt; foldr1 f xs = foldr1' f xs
</li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldl1" class="def">foldl1</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#foldl1" class="link">Source</a></p><div class="doc"><p>Combine all the elements of a non-empty sequence into
   a single value, given a combining function.  The function
   is applied with left nesting. Signals an error if the
   sequence is empty.
</p><pre> foldl1 (+) &lt;x0,...,xn-1&gt;
  | n==0 = error &quot;ModuleName.foldl1: empty sequence&quot;
  | n&gt;0  = (x0 + x1) + ... + xn-1
</pre><p><em>Axioms:</em>
</p><ul><li><pre>foldl1 f empty = undefined</pre></li><li><pre>foldl1 f (lcons x xs) = foldl f x xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldl1-39-" class="def">foldl1'</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#foldl1%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:foldl1">foldl1</a></code>.
</p><p><em>Axioms:</em>
</p><ul><li> forall a. f _|_ a = _|_ ==&gt; foldl1 f xs = foldl1' f xs
</li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:reducer" class="def">reducer</a> ::  (a -&gt; a -&gt; a) -&gt; a -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#reducer" class="link">Source</a></p><div class="doc"><p>See <code><a href="Data-Edison-Seq.html#v:reduce1">reduce1</a></code> for additional notes.
</p><pre> reducer f x xs = reduce1 f (cons x xs)
</pre><p><em>Axioms:</em>
</p><ul><li> <code>reducer f c xs = foldr f c xs</code> for associative <code>f</code>
</li></ul><p><code>reducer f</code> is unambiguous iff <code>f</code> is an associative function.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:reducer-39-" class="def">reducer'</a> ::  (a -&gt; a -&gt; a) -&gt; a -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#reducer%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:reducer">reducer</a></code>.
</p><p>See <code><a href="Data-Edison-Seq.html#v:reduce1">reduce1</a></code> for additional notes.
</p><p><em>Axioms:</em>
</p><ul><li><pre>forall a. f a _|_ = _|_ &amp;&amp; forall a. f _|_ a = _|_ ==&gt;
          reducer f x xs = reducer' f x xs</pre></li></ul><p><code>reducer' f</code> is unambiguous iff <code>f</code> is an associative function.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:reducel" class="def">reducel</a> ::  (a -&gt; a -&gt; a) -&gt; a -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#reducel" class="link">Source</a></p><div class="doc"><p>See <code><a href="Data-Edison-Seq.html#v:reduce1">reduce1</a></code> for additional notes.
</p><pre> reducel f x xs = reduce1 f (rcons x xs)
</pre><p><em>Axioms:</em>
</p><ul><li> <code>reducel f c xs = foldl f c xs</code> for associative <code>f</code>
</li></ul><p><code>reducel f</code> is unambiguous iff <code>f</code> is an associative function.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:reducel-39-" class="def">reducel'</a> ::  (a -&gt; a -&gt; a) -&gt; a -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#reducel%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:reducel">reducel</a></code>.
</p><p>See <code><a href="Data-Edison-Seq.html#v:reduce1">reduce1</a></code> for additional notes.
</p><p><em>Axioms:</em>
</p><ul><li><pre>forall a. f a _|_ = _|_ &amp;&amp; forall a. f _|_ a = _|_ ==&gt;
          reducel f x xs = reducel' f x xs</pre></li></ul><p><code>reducel' f</code> is unambiguous iff <code>f</code> is an associative function.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:reduce1" class="def">reduce1</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#reduce1" class="link">Source</a></p><div class="doc"><p>A reduce is similar to a fold, but combines elements in a balanced fashion.
   The combining function should usually be associative.  If the combining
   function is associative, the various reduce functions yield the same
   results as the corresponding folds.
</p><p>What is meant by &quot;in a balanced fashion&quot;?  We mean that
   <code>reduce1 (%) &lt;x0,x1,...,xn-1&gt;</code> equals some complete parenthesization of
   <code>x0 % x1 % ... % xn-1</code> such that the nesting depth of parentheses
   is <code>O( log n )</code>.  The precise shape of this parenthesization is
   unspecified.
</p><pre> reduce1 f &lt;x&gt; = x
 reduce1 f &lt;x0,...,xn-1&gt; =
     f (reduce1 f &lt;x0,...,xi&gt;) (reduce1 f &lt;xi+1,...,xn-1&gt;)
</pre><p>for some <code>i</code> such that <code> 0 &lt;= i &amp;&amp; i &lt; n-1 </code>
</p><p>Although the exact value of i is unspecified it tends toward <code>n/2</code>
   so that the depth of calls to <code>f</code> is at most logarithmic.
</p><p>Note that <code>reduce</code>* are some of the only sequence operations for which
   different implementations are permitted to yield different answers.  Also
   note that a single implementation may choose different parenthisizations
   for different sequences, even if they are the same length.  This will
   typically happen when the sequences were constructed differently.
</p><p>The canonical applications of the reduce functions are algorithms like
   merge sort where:
</p><pre> mergesort xs = reducer merge empty (map singleton xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>reduce1 f empty = undefined</pre></li><li> <code>reduce1 f xs = foldr1 f xs = foldl1 f xs</code> for associative <code>f</code>
</li></ul><p><code>reduce1 f</code> is unambiguous iff <code>f</code> is an associative function.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:reduce1-39-" class="def">reduce1'</a> ::  (a -&gt; a -&gt; a) -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#reduce1%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:reduce1">reduce1</a></code>.
</p><p><em>Axioms:</em>
</p><ul><li><pre>forall a. f a _|_ = _|_ &amp;&amp; forall a. f _|_ a = _|_ ==&gt;
          reduce1 f xs = reduce1' f xs</pre></li></ul><p><code>reduce1' f</code> is unambiguous iff <code>f</code> is an associative function.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:take" class="def">take</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#take" class="link">Source</a></p><div class="doc"><p>Extract a prefix of length <code>i</code> from the sequence.  Return
   <code><a href="Data-Edison-Seq.html#v:empty">empty</a></code> if <code>i</code> is negative, or the entire sequence if <code>i</code>
   is too large.
</p><pre> take i xs = fst (splitAt i xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>i &lt; 0        ==&gt; take i xs = empty</pre></li><li><pre>i &gt; size xs  ==&gt; take i xs = xs</pre></li><li><pre>size xs == i ==&gt; take i (append xs ys) = xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i )</code>
</p></div><p class="src"><a name="v:drop" class="def">drop</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#drop" class="link">Source</a></p><div class="doc"><p>Delete a prefix of length <code>i</code> from a sequence.  Return
   the entire sequence if <code>i</code> is negative, or <code><a href="Data-Edison-Seq.html#v:empty">empty</a></code> if
   <code>i</code> is too large.
</p><pre> drop i xs = snd (splitAt i xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>i &lt; 0        ==&gt; drop i xs = xs</pre></li><li><pre>i &gt; size xs  ==&gt; drop i xs = empty</pre></li><li><pre>size xs == i ==&gt; drop i (append xs ys) = ys</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i )</code>
</p></div><p class="src"><a name="v:splitAt" class="def">splitAt</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; (s a, s a)<a href="src/Data-Edison-Seq.html#splitAt" class="link">Source</a></p><div class="doc"><p>Split a sequence into a prefix of length <code>i</code>
   and the remaining sequence.  Behaves the same
   as the corresponding calls to <code><a href="Data-Edison-Seq.html#v:take">take</a></code> and <code><a href="Data-Edison-Seq.html#v:drop">drop</a></code>
   if <code>i</code> is negative or too large.
</p><pre> splitAt i xs
  | i &lt; 0  = (&lt;&gt;           , &lt;x0,...,xn-1&gt;)
  | i &lt; n  = (&lt;x0,...,xi-1&gt;, &lt;xi,...,xn-1&gt;)
  | i &gt;= n = (&lt;x0,...,xn-1&gt;, &lt;&gt;           )
</pre><p><em>Axioms:</em>
</p><ul><li><pre>splitAt i xs = (take i xs,drop i xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i )</code>
</p></div><p class="src"><a name="v:subseq" class="def">subseq</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#subseq" class="link">Source</a></p><div class="doc"><p>Extract a subsequence from a sequence.  The integer
   arguments are &quot;start index&quot; and &quot;length&quot; NOT
   &quot;start index&quot; and &quot;end index&quot;.  Behaves the same
   as the corresponding calls to <code><a href="Data-Edison-Seq.html#v:take">take</a></code> and <code><a href="Data-Edison-Seq.html#v:drop">drop</a></code> if the
   start index or length are negative or too large.
</p><pre> subseq i len xs = take len (drop i xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>subseq i len xs = take len (drop i xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i + len )</code>
</p></div><p class="src"><a name="v:filter" class="def">filter</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#filter" class="link">Source</a></p><div class="doc"><p>Extract the elements of a sequence that satisfy the
   given predicate, retaining the relative ordering of
   elements from the original sequence.
</p><pre> filter p xs = foldr pcons empty xs
      where pcons x xs = if p x then cons x xs else xs
</pre><p><em>Axioms:</em>
</p><ul><li><pre>filter p empty = empty</pre></li><li><pre>filter p (lcons x xs) = if p x 
       then lcons x (filter p xs)
       else filter p xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>p</code>
</p></div><p class="src"><a name="v:partition" class="def">partition</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; (s a, s a)<a href="src/Data-Edison-Seq.html#partition" class="link">Source</a></p><div class="doc"><p>Separate the elements of a sequence into those that
   satisfy the given predicate and those that do not,
   retaining the relative ordering of elements from the
   original sequence.
</p><pre> partition p xs = (filter p xs, filter (not . p) xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>partition p xs = (filter p xs, filter (not . p) xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>p</code>
</p></div><p class="src"><a name="v:takeWhile" class="def">takeWhile</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#takeWhile" class="link">Source</a></p><div class="doc"><p>Extract the maximal prefix of elements satisfying the
   given predicate.
</p><pre> takeWhile p xs = fst (splitWhile p xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>takeWhile p empty = empty</pre></li><li><pre>takeWhile p (lcons x xs) = if p x
       then lcons x (takeWhile p xs)
       else empty</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>p</code>
</p></div><p class="src"><a name="v:dropWhile" class="def">dropWhile</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#dropWhile" class="link">Source</a></p><div class="doc"><p>Delete the maximal prefix of elements satisfying the
   given predicate.
</p><pre> dropWhile p xs = snd (splitWhile p xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>dropWhile p empty = empty</pre></li><li><pre>dropWhile p (lcons x xs) = if p x
      then dropWhile p xs
      else lcons x xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>p</code>
</p></div><p class="src"><a name="v:splitWhile" class="def">splitWhile</a> ::  (a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a>) -&gt; s a -&gt; (s a, s a)<a href="src/Data-Edison-Seq.html#splitWhile" class="link">Source</a></p><div class="doc"><p>Split a sequence into the maximal prefix of elements
   satisfying the given predicate, and the remaining sequence.
</p><pre> splitWhile p &lt;x0,...,xn-1&gt; = (&lt;x0,...,xi-1&gt;, &lt;xi,...,xn-1&gt;)
   where i = min j such that p xj (or n if no such j)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>splitWhile p xs = (takeWhile p xs,dropWhile p xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>p</code>
</p></div><p class="src"><a name="v:inBounds" class="def">inBounds</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a><a href="src/Data-Edison-Seq.html#inBounds" class="link">Source</a></p><div class="doc"><p>Test whether an index is valid for the given sequence. All indexes
   are 0 based.
</p><pre> inBounds i &lt;x0,...,xn-1&gt; = (0 &lt;= i &amp;&amp; i &lt; n)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>inBounds i xs = (0 &lt;= i &amp;&amp; i &lt; size xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i )</code>
</p></div><p class="src"><a name="v:lookup" class="def">lookup</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#lookup" class="link">Source</a></p><div class="doc"><p>Return the element at the given index.  All indexes are 0 based.
   Signals error if the index out of bounds.
</p><pre> lookup i xs@&lt;x0,...,xn-1&gt;
   | inBounds i xs = xi
   | otherwise = error &quot;ModuleName.lookup: index out of bounds&quot;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>not (inBounds i xs)  ==&gt; lookup i xs = undefined</pre></li><li><pre>size xs == i ==&gt; lookup i (append xs (lcons x ys)) = x</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i )</code>
</p></div><p class="src"><a name="v:lookupM" class="def">lookupM</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#t:Monad">Monad</a> m =&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; m a<a href="src/Data-Edison-Seq.html#lookupM" class="link">Source</a></p><div class="doc"><p>Return the element at the given index.  All indexes are 0 based.
   Calls <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Control-Monad.html#v:fail">fail</a></code> if the index is out of bounds.
</p><pre> lookupM i xs@&lt;x0,...,xn-1&gt;
   | inBounds i xs = Just xi
   | otherwise = Nothing
</pre><p><em>Axioms:</em>
</p><ul><li><pre>not (inBounds i xs) ==&gt; lookupM i xs = fail</pre></li><li><pre>size xs == i ==&gt; lookupM i (append xs (lcons x ys)) = return x</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i )</code>
</p></div><p class="src"><a name="v:lookupWithDefault" class="def">lookupWithDefault</a> ::  a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; a<a href="src/Data-Edison-Seq.html#lookupWithDefault" class="link">Source</a></p><div class="doc"><p>Return the element at the given index, or the
   default argument if the index is out of bounds.  All indexes are
   0 based.
</p><pre> lookupWithDefault d i xs@&lt;x0,...,xn-1&gt;
   | inBounds i xs = xi
   | otherwise = d
</pre><p><em>Axioms:</em>
</p><ul><li><pre>not (inBounds i xs) ==&gt; lookupWithDefault d i xs = d</pre></li><li><pre>size xs == i ==&gt; lookupWithDefault d i (append xs (lcons x ys)) = x</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i )</code>
</p></div><p class="src"><a name="v:update" class="def">update</a> ::  <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#update" class="link">Source</a></p><div class="doc"><p>Replace the element at the given index, or return
   the original sequence if the index is out of bounds.
   All indexes are 0 based.
</p><pre> update i y xs@&lt;x0,...,xn-1&gt;
   | inBounds i xs = &lt;x0,...xi-1,y,xi+1,...,xn-1&gt;
   | otherwise = xs
</pre><p><em>Axioms:</em>
</p><ul><li><pre>not (inBounds i xs) ==&gt; update i y xs = xs</pre></li><li><pre>size xs == i ==&gt; update i y (append xs (lcons x ys)) =
      append xs (lcons y ys)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i )</code>
</p></div><p class="src"><a name="v:adjust" class="def">adjust</a> ::  (a -&gt; a) -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#adjust" class="link">Source</a></p><div class="doc"><p>Apply a function to the element at the given index, or
   return the original sequence if the index is out of bounds.
   All indexes are 0 based.
</p><pre> adjust f i xs@&lt;x0,...,xn-1&gt;
   | inBounds i xs = &lt;x0,...xi-1,f xi,xi+1,...,xn-1&gt;
   | otherwise = xs
</pre><p><em>Axioms:</em>
</p><ul><li><pre>not (inBounds i xs) ==&gt; adjust f i xs = xs</pre></li><li><pre>size xs == i ==&gt; adjust f i (append xs (lcons x ys)) =
      append xs (cons (f x) ys)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( i + t )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:mapWithIndex" class="def">mapWithIndex</a> ::  (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b) -&gt; s a -&gt; s b<a href="src/Data-Edison-Seq.html#mapWithIndex" class="link">Source</a></p><div class="doc"><p>Like <code><a href="Data-Edison-Seq.html#v:map">map</a></code>, but include the index with each element.
   All indexes are 0 based.
</p><pre> mapWithIndex f &lt;x0,...,xn-1&gt; = &lt;f 0 x0,...,f (n-1) xn-1&gt;
</pre><p><em>Axioms:</em>
</p><ul><li><pre>mapWithIndex f empty = empty</pre></li><li><pre>mapWithIndex f (rcons x xs) = rcons (f (size xs) x) (mapWithIndex f xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldrWithIndex" class="def">foldrWithIndex</a> ::  (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#foldrWithIndex" class="link">Source</a></p><div class="doc"><p>Like <code><a href="Data-Edison-Seq.html#v:foldr">foldr</a></code>, but include the index with each element.
   All indexes are 0 based.
</p><pre> foldrWithIndex f c &lt;x0,...,xn-1&gt; = 
     f 0 x0 (f 1 x1 (... (f (n-1) xn-1 c)))
</pre><p><em>Axioms:</em>
</p><ul><li><pre>foldrWithIndex f c empty = c</pre></li><li><pre>foldrWithIndex f c (rcons x xs) =
      foldrWithIndex f (f (size xs) x c) xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldrWithIndex-39-" class="def">foldrWithIndex'</a> ::  (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#foldrWithIndex%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:foldrWithIndex">foldrWithIndex</a></code>.
</p><p><em>Axioms:</em>
</p><ul><li><pre>forall i a. f i a _|_ = _|_ ==&gt; foldrWithIndex f x xs = 
       foldrWithIndex' f x xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldlWithIndex" class="def">foldlWithIndex</a> ::  (b -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#foldlWithIndex" class="link">Source</a></p><div class="doc"><p>Like <code><a href="Data-Edison-Seq.html#v:foldl">foldl</a></code>, but include the index with each element.
   All indexes are 0 based.
</p><pre> foldlWithIndex f c &lt;x0,...,xn-1&gt; =
     f (...(f (f c 0 x0) 1 x1)...) (n-1) xn-1)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>foldlWithIndex f c empty = c</pre></li><li><pre>foldlWithIndex f c (rcons x xs) =
      f (foldlWithIndex f c xs) (size xs) x</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:foldlWithIndex-39-" class="def">foldlWithIndex'</a> ::  (b -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a> -&gt; a -&gt; b) -&gt; b -&gt; s a -&gt; b<a href="src/Data-Edison-Seq.html#foldlWithIndex%27" class="link">Source</a></p><div class="doc"><p>Strict variant of <code><a href="Data-Edison-Seq.html#v:foldlWithIndex">foldlWithIndex</a></code>.
</p><p><em>Axioms:</em>
</p><ul><li><pre>forall i a. f _|_ i a = _|_ ==&gt; foldlWithIndex f x xs = 
       foldlWithIndex' f x xs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:zip" class="def">zip</a> ::  s a -&gt; s b -&gt; s (a, b)<a href="src/Data-Edison-Seq.html#zip" class="link">Source</a></p><div class="doc"><p>Combine two sequences into a sequence of pairs.  If the
   sequences are different lengths, the excess elements of the
   longer sequence is discarded.
</p><pre> zip &lt;x0,...,xn-1&gt; &lt;y0,...,ym-1&gt; = &lt;(x0,y0),...,(xj-1,yj-1)&gt;
     where j = min {n,m}
</pre><p><em>Axioms:</em>
</p><ul><li><pre>zip xs ys = zipWith (,) xs ys</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( min( n1, n2 ) )</code>
</p></div><p class="src"><a name="v:zip3" class="def">zip3</a> ::  s a -&gt; s b -&gt; s c -&gt; s (a, b, c)<a href="src/Data-Edison-Seq.html#zip3" class="link">Source</a></p><div class="doc"><p>Like <code><a href="Data-Edison-Seq.html#v:zip">zip</a></code>, but combines three sequences into triples.
</p><pre> zip3 &lt;x0,...,xn-1&gt; &lt;y0,...,ym-1&gt; &lt;z0,...,zk-1&gt; = 
      &lt;(x0,y0,z0),...,(xj-1,yj-1,zj-1)&gt;
    where j = min {n,m,k}
</pre><p><em>Axioms:</em>
</p><ul><li><pre>zip3 xs ys zs = zipWith3 (,,) xs ys zs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( min( n1, n2, n3 ) )</code>
</p></div><p class="src"><a name="v:zipWith" class="def">zipWith</a> ::  (a -&gt; b -&gt; c) -&gt; s a -&gt; s b -&gt; s c<a href="src/Data-Edison-Seq.html#zipWith" class="link">Source</a></p><div class="doc"><p>Combine two sequences into a single sequence by mapping
   a combining function across corresponding elements.  If
   the sequences are of different lengths, the excess elements
   of the longer sequence are discarded.
</p><pre> zipWith f xs ys = map (uncurry f) (zip xs ys)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>zipWith f (lcons x xs) (lcons y ys) =
     lcons (f x y) (zipWith f xs ys)</pre></li><li><pre>(null xs || null ys) ==&gt; zipWith xs ys = empty</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * min( n1, n2 ) )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:zipWith3" class="def">zipWith3</a> ::  (a -&gt; b -&gt; c -&gt; d) -&gt; s a -&gt; s b -&gt; s c -&gt; s d<a href="src/Data-Edison-Seq.html#zipWith3" class="link">Source</a></p><div class="doc"><p>Like <code><a href="Data-Edison-Seq.html#v:zipWith">zipWith</a></code> but for a three-place function and three
   sequences.
</p><pre> zipWith3 f xs ys zs = map (uncurry f) (zip3 xs ys zs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>zipWith3 (lcons x xs) (lcons y ys) (lcons z zs) =
      lcons (f x y z) (zipWith3 f xs ys zs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * min( n1, n2, n3 ) )</code>
     where <code>t</code> is the running time of <code>f</code>
</p></div><p class="src"><a name="v:unzip" class="def">unzip</a> ::  s (a, b) -&gt; (s a, s b)<a href="src/Data-Edison-Seq.html#unzip" class="link">Source</a></p><div class="doc"><p>Transpose a sequence of pairs into a pair of sequences.
</p><pre> unzip xs = (map fst xs, map snd xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>unzip xys = unzipWith fst snd xys</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:unzip3" class="def">unzip3</a> ::  s (a, b, c) -&gt; (s a, s b, s c)<a href="src/Data-Edison-Seq.html#unzip3" class="link">Source</a></p><div class="doc"><p>Transpose a sequence of triples into a triple of sequences
</p><pre> unzip3 xs = (map fst3 xs, map snd3 xs, map thd3 xs)
    where fst3 (x,y,z) = x
          snd3 (x,y,z) = y
          thd3 (x,y,z) = z
</pre><p><em>Axioms:</em>
</p><ul><li><pre>unzip3 xyzs = unzipWith3 fst3 snd3 thd3 xyzs</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:unzipWith" class="def">unzipWith</a> ::  (a -&gt; b) -&gt; (a -&gt; c) -&gt; s a -&gt; (s b, s c)<a href="src/Data-Edison-Seq.html#unzipWith" class="link">Source</a></p><div class="doc"><p>Map two functions across every element of a sequence,
   yielding a pair of sequences
</p><pre> unzipWith f g xs = (map f xs, map g xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>unzipWith f g xs = (map f xs, map g xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the maximum running time
     of <code>f</code> and <code>g</code>
</p></div><p class="src"><a name="v:unzipWith3" class="def">unzipWith3</a> ::  (a -&gt; b) -&gt; (a -&gt; c) -&gt; (a -&gt; d) -&gt; s a -&gt; (s b, s c, s d)<a href="src/Data-Edison-Seq.html#unzipWith3" class="link">Source</a></p><div class="doc"><p>Map three functions across every element of a sequence,
   yielding a triple of sequences.
</p><pre> unzipWith3 f g h xs = (map f xs, map g xs, map h xs)
</pre><p><em>Axioms:</em>
</p><ul><li><pre>unzipWith3 f g h xs = (map f xs,map g xs,map h xs)</pre></li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( t * n )</code>
     where <code>t</code> is the maximum running time
     of <code>f</code>, <code>g</code>, and <code>h</code>
</p></div><p class="src"><a name="v:strict" class="def">strict</a> ::  s a -&gt; s a<a href="src/Data-Edison-Seq.html#strict" class="link">Source</a></p><div class="doc"><p>Semanticly, this function is a partial identity function.  If the
   datastructure is infinite in size or contains exceptions or non-termination
   in the structure itself, then <code>strict</code> will result in bottom.  Operationally,
   this function walks the datastructure forcing any closures.  Elements contained
   in the sequence are <em>not</em> forced.
</p><p><em>Axioms:</em>
</p><ul><li> <code>strict xs = xs</code> OR <code>strict xs = _|_</code>
</li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: <code>O( n )</code>
</p></div><p class="src"><a name="v:strictWith" class="def">strictWith</a> ::  (a -&gt; b) -&gt; s a -&gt; s a<a href="src/Data-Edison-Seq.html#strictWith" class="link">Source</a></p><div class="doc"><p>Similar to <code><a href="Data-Edison-Seq.html#v:strict">strict</a></code>, this function walks the datastructure forcing closures.
   However, <code>strictWith</code> will additionally apply the given function to the
   sequence elements, force the result using <code>seq</code>, and then ignore it.
   This function can be used to perform various levels of forcing on the
   sequence elements.  In particular:
</p><pre> strictWith id xs
</pre><p>will force the spine of the datastructure and reduce each element to WHNF.
</p><p><em>Axioms:</em>
</p><ul><li> forall <code>f :: a -&gt; b</code>, <code>strictWith f xs = xs</code> OR <code>strictWith f xs = _|_</code>
</li></ul><p>This function is always <em>unambiguous</em>.
</p><p>Default running time: unbounded (forcing element closures can take arbitrairly long)
</p></div><p class="src"><a name="v:structuralInvariant" class="def">structuralInvariant</a> ::  s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a><a href="src/Data-Edison-Seq.html#structuralInvariant" class="link">Source</a></p><div class="doc"><p>A method to facilitate unit testing.  Returns <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#v:True">True</a></code> if the structural
   invariants of the implementation hold for the given sequence.  If
   this function returns <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#v:False">False</a></code>, it represents a bug in the implementation.
</p></div><p class="src"><a name="v:instanceName" class="def">instanceName</a> ::  s a -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a><a href="src/Data-Edison-Seq.html#instanceName" class="link">Source</a></p><div class="doc"><p>The name of the module implementing s.
</p></div></div><div class="subs instances"><p id="control.i:Sequence" class="caption collapser" onclick="toggleSection('i:Sequence')">Instances</p><div id="section.i:Sequence" class="show"><table><tr><td class="src"><a href="Data-Edison-Seq.html#t:Sequence">Sequence</a> []</td><td class="doc empty">&nbsp;</td></tr></table></div></div></div></div></div><div id="footer"><p>Produced by <a href="http://www.haskell.org/haddock/">Haddock</a> version 2.10.0</p></div></body></html>