Changes

|<code><b>fn:map</b>($f as function(item()) as item()*, $seq as item()*) as item()*</code><br />

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|Applies the function item <code>$f</code> to every element of the sequence <code>$seq</code> and returns all of the results as a sequence.

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<ul><li>Squaring all numbers from 1 to 10:

</li></ul>

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|<pre class="brush:xquery">

declare function local:map(

|<code><b>fn:filter</b>($pred as function(item()) as xs:boolean, $seq as item()*) as item()*</code><br />

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|Applies the boolean predicate <code>$pred</code> to all elements of the sequence <code>$seq</code>, returning those for which it returns <code>true()</code>.

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|<ul><li>All even integers until 10:

<pre class="brush:xquery">

</li></ul>

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|<code>fn:filter</code> can be easily implemented with <code>fn:map</code>:

<pre class="brush:xquery">

</pre>

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|<pre class="brush:xquery">

declare function local:filter(

|<code><b>fn:map-pairs</b>($f as function(item(), item()) as item()*, $seq1 as item()*, $seq2 as item()*) as item()*</code><br />

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|''zips'' the elements from the two sequences <code>$seq1</code> and <code>$seq2</code> together with the function <code>$f</code>. It stops after the shorter sequence ends.

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|<ul><li>Adding one to the numbers at odd positions:

<pre class="brush:xquery">

''Result:'' <code>true false</code>

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|<pre class="brush:xquery">

declare function local:map-pairs(

|<code><b>fn:fold-left</b>($f as function(item()*, item()) as item()*, $seed as item()*, $seq as item()*) as item()*</code><br />

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|The ''left fold'' traverses the sequence from the left.

The query <code>fn:fold-left($f, 0, 1 to 5)</code> for example would be evaluated as:

</pre>

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|<ul><li>Product of a sequence of integers:

<pre class="brush:xquery">

</li></ul>

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|As folds are more general than ''FLWOR'' expressions, the implementation isn't as concise as the former ones:

<pre class="brush:xquery">

|<code><b>fn:fold-right</b>($f as function(item(), item()*) as item()*, $seed as item()*, $seq as item()*) as item()*</code><br />

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|The ''right fold'' <code>fn:fold-right($f, $seed, $seq)</code> traverses the from the right.

The query <code>fn:fold-right($f, 0, 1 to 5)</code> for example would be evaluated as:

</pre>

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|<ul><li>Product of a sequence of integers:

<pre class="brush:xquery">

</li></ul>

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|<pre class="brush:xquery">

declare function local:fold-right(