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<h1>Module <a href="type_Seq.html">Seq</a></h1> <pre><span id="MODULESeq"><span class="keyword">module</span> Seq</span>: <code class="code"><span class="keyword">sig</span></code> <a href="Seq.html">..</a> <code class="code"><span class="keyword">end</span></code></pre><div class="info module top"> <div class="info-desc"> <h2 id="1_FunctionalIterators">Functional Iterators</h2></div> </div> <hr width="100%"> <p>The type <code class="code"><span class="keywordsign">'</span>a t</code> is a <b>delayed list</b>, i.e. a list where some evaluation is needed to access the next element. This makes it possible to build infinite sequences, to build sequences as we traverse them, and to transform them in a lazy fashion rather than upfront.</p> <pre><span id="TYPEt"><span class="keyword">type</span> <code class="type">'a</code> t</span> = <code class="type">unit -> 'a <a href="Seq.html#TYPEnode">node</a></code> </pre> <div class="info "> <div class="info-desc"> <p>The type of delayed lists containing elements of type <code class="code"><span class="keywordsign">'</span>a</code>. Note that the concrete list node <code class="code"><span class="keywordsign">'</span>a node</code> is delayed under a closure, not a <code class="code"><span class="keyword">lazy</span></code> block, which means it might be recomputed every time we access it.</p> </div> </div> <pre><code><span id="TYPEnode"><span class="keyword">type</span> <code class="type">'a</code> node</span> = </code></pre><table class="typetable"> <tr> <td align="left" valign="top" > <code><span class="keyword">|</span></code></td> <td align="left" valign="top" > <code><span id="TYPEELTnode.Nil"><span class="constructor">Nil</span></span></code></td> </tr> <tr> <td align="left" valign="top" > <code><span class="keyword">|</span></code></td> <td align="left" valign="top" > <code><span id="TYPEELTnode.Cons"><span class="constructor">Cons</span></span> <span class="keyword">of</span> <code class="type">'a * 'a <a href="Seq.html#TYPEt">t</a></code></code></td> <td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><div class="info "> <div class="info-desc"> <p>A fully-evaluated list node, either empty or containing an element and a delayed tail.</p> </div> </div> </td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td> </tr></table> <pre><span id="VALempty"><span class="keyword">val</span> empty</span> : <code class="type">'a <a href="Seq.html#TYPEt">t</a></code></pre><div class="info "> <div class="info-desc"> <p>The empty sequence, containing no elements.</p> </div> </div> <pre><span id="VALreturn"><span class="keyword">val</span> return</span> : <code class="type">'a -> 'a <a href="Seq.html#TYPEt">t</a></code></pre><div class="info "> <div class="info-desc"> <p>The singleton sequence containing only the given element.</p> </div> </div> <pre><span id="VALmap"><span class="keyword">val</span> map</span> : <code class="type">('a -> 'b) -> 'a <a href="Seq.html#TYPEt">t</a> -> 'b <a href="Seq.html#TYPEt">t</a></code></pre><div class="info "> <div class="info-desc"> <p><code class="code">map f seq</code> returns a new sequence whose elements are the elements of <code class="code">seq</code>, transformed by <code class="code">f</code>. This transformation is lazy, it only applies when the result is traversed.</p> <p>If <code class="code">seq = [1;2;3]</code>, then <code class="code">map f seq = [f 1; f 2; f 3]</code>.</p> </div> </div> <pre><span id="VALfilter"><span class="keyword">val</span> filter</span> : <code class="type">('a -> bool) -> 'a <a href="Seq.html#TYPEt">t</a> -> 'a <a href="Seq.html#TYPEt">t</a></code></pre><div class="info "> <div class="info-desc"> <p>Remove from the sequence the elements that do not satisfy the given predicate. This transformation is lazy, it only applies when the result is traversed.</p> </div> </div> <pre><span id="VALfilter_map"><span class="keyword">val</span> filter_map</span> : <code class="type">('a -> 'b option) -> 'a <a href="Seq.html#TYPEt">t</a> -> 'b <a href="Seq.html#TYPEt">t</a></code></pre><div class="info "> <div class="info-desc"> <p>Apply the function to every element; if <code class="code">f x = <span class="constructor">None</span></code> then <code class="code">x</code> is dropped; if <code class="code">f x = <span class="constructor">Some</span> y</code> then <code class="code">y</code> is returned. This transformation is lazy, it only applies when the result is traversed.</p> </div> </div> <pre><span id="VALflat_map"><span class="keyword">val</span> flat_map</span> : <code class="type">('a -> 'b <a href="Seq.html#TYPEt">t</a>) -> 'a <a href="Seq.html#TYPEt">t</a> -> 'b <a href="Seq.html#TYPEt">t</a></code></pre><div class="info "> <div class="info-desc"> <p>Map each element to a subsequence, then return each element of this sub-sequence in turn. This transformation is lazy, it only applies when the result is traversed.</p> </div> </div> <pre><span id="VALfold_left"><span class="keyword">val</span> fold_left</span> : <code class="type">('a -> 'b -> 'a) -> 'a -> 'b <a href="Seq.html#TYPEt">t</a> -> 'a</code></pre><div class="info "> <div class="info-desc"> <p>Traverse the sequence from left to right, combining each element with the accumulator using the given function. The traversal happens immediately and will not terminate on infinite sequences.</p> <p>Also see <a href="List.html#VALfold_left"><code class="code"><span class="constructor">List</span>.fold_left</code></a></p> </div> </div> <pre><span id="VALiter"><span class="keyword">val</span> iter</span> : <code class="type">('a -> unit) -> 'a <a href="Seq.html#TYPEt">t</a> -> unit</code></pre><div class="info "> <div class="info-desc"> <p>Iterate on the sequence, calling the (imperative) function on every element. The traversal happens immediately and will not terminate on infinite sequences.</p> </div> </div> </body></html>