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<h4 class="subsubsection" id="SRFI_002d43-Iteration-1"><span>7.5.30.4 SRFI-43 Iteration<a class="copiable-link" href="#SRFI_002d43-Iteration-1"> &para;</a></span></h4>
<dl class="first-deffn">
<dt class="deffn" id="index-vector_002dfold"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">vector-fold</strong> <var class="def-var-arguments">kons knil vec1 vec2 &hellip;</var><a class="copiable-link" href="#index-vector_002dfold"> &para;</a></span></dt>
<dd><p>The fundamental vector iterator. <var class="var">kons</var> is iterated over each index
in all of the vectors, stopping at the end of the shortest; <var class="var">kons</var>
is applied as
</p><div class="example smalllisp lisp">
<pre class="lisp-preformatted">(kons i state (vector-ref vec1 i) (vector-ref vec2 i) ...)
</pre></div>
<p>where <var class="var">state</var> is the current state value, and <var class="var">i</var> is the current
index. The current state value begins with <var class="var">knil</var>, and becomes
whatever <var class="var">kons</var> returned at the respective iteration. The iteration
is strictly left-to-right.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-vector_002dfold_002dright"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">vector-fold-right</strong> <var class="def-var-arguments">kons knil vec1 vec2 &hellip;</var><a class="copiable-link" href="#index-vector_002dfold_002dright"> &para;</a></span></dt>
<dd><p>Similar to <code class="code">vector-fold</code>, but it iterates right-to-left instead of
left-to-right.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-vector_002dmap"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">vector-map</strong> <var class="def-var-arguments">f vec1 vec2 &hellip;</var><a class="copiable-link" href="#index-vector_002dmap"> &para;</a></span></dt>
<dd><p>Return a new vector of the shortest size of the vector arguments. Each
element at index i of the new vector is mapped from the old vectors by
</p><div class="example smalllisp lisp">
<pre class="lisp-preformatted">(f i (vector-ref vec1 i) (vector-ref vec2 i) ...)
</pre></div>
<p>The dynamic order of application of <var class="var">f</var> is unspecified.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-vector_002dmap_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">vector-map!</strong> <var class="def-var-arguments">f vec1 vec2 &hellip;</var><a class="copiable-link" href="#index-vector_002dmap_0021"> &para;</a></span></dt>
<dd><p>Similar to <code class="code">vector-map</code>, but rather than mapping the new elements
into a new vector, the new mapped elements are destructively inserted
into <var class="var">vec1</var>. The dynamic order of application of <var class="var">f</var> is
unspecified.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-vector_002dfor_002deach"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">vector-for-each</strong> <var class="def-var-arguments">f vec1 vec2 &hellip;</var><a class="copiable-link" href="#index-vector_002dfor_002deach"> &para;</a></span></dt>
<dd><p>Call <code class="code">(f i (vector-ref vec1 i) (vector-ref vec2 i) ...)</code> for each
index i less than the length of the shortest vector passed. The
iteration is strictly left-to-right.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-vector_002dcount"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">vector-count</strong> <var class="def-var-arguments">pred? vec1 vec2 &hellip;</var><a class="copiable-link" href="#index-vector_002dcount"> &para;</a></span></dt>
<dd><p>Count the number of parallel elements in the vectors that satisfy
<var class="var">pred?</var>, which is applied, for each index i less than the length of
the smallest vector, to i and each parallel element in the vectors at
that index, in order.
</p>
<div class="example">
<pre class="example-preformatted">(vector-count (lambda (i elt) (even? elt))
'#(3 1 4 1 5 9 2 5 6))
&rArr; 3
(vector-count (lambda (i x y) (&lt; x y))
'#(1 3 6 9) '#(2 4 6 8 10 12))
&rArr; 2
</pre></div>
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