Higher-Order Functions Module - Revision history

CG: Text replacement - "" to "

2023-12-01T16:35:06Z

Text replacement - "<syntaxhighlight lang="xquery">" to "<pre lang='xquery'>"

CG: Text replacement - "" to ""

2023-12-01T16:31:41Z

Text replacement - "</syntaxhighlight>" to "</pre>"

CG at 08:47, 27 November 2023

2023-11-27T08:47:12Z

CG at 15:20, 11 November 2023

2023-11-11T15:20:20Z

CG at 14:46, 11 November 2023

2023-11-11T14:46:21Z

CG at 14:46, 11 November 2023

2023-11-11T14:46:01Z

CG: /* Changelog */

2023-11-11T14:45:25Z

Changelog

CG at 14:45, 11 November 2023

2023-11-11T14:45:08Z

Andy Bunce: signatures add comma

2023-07-03T13:22:45Z

signatures add comma

Andy Bunce: signatures

2023-07-03T13:06:25Z

signatures

@@ Line 59: / Line 59: @@
 | '''Summary'''
 |This function is similar to [[Higher-Order Functions#fn:fold-left|fn:fold-left]], but it returns a list of successive reduced values from the left. It is equivalent to:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 declare function hof:scan-left($input, $acc, $action) {
    if(empty($input)) then $acc else (
@@ Line 71: / Line 71: @@
+|
 * Returns triangular numbers:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 hof:scan-left(1 to 10, 0, function($a, $b) { $a + $b })
 </pre>
@@ Line 91: / Line 91: @@
 | '''Summary'''
 |Returns the {{Code|$k}} items in {{Code|$input}} that are greatest when sorted by the result of {{Code|$key}} applied to the item. The function is a much more efficient implementation of the following scheme:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 (for $item in $input
   order by $key($item) descending
@@ Line 144: / Line 144: @@
 * {{Code|hof:const(42, 1337)}} returns {{Code|42}}.
 * With higher-order functions:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 let $zip-sum := function($f, $seq1, $seq2) {
    sum(for-each-pair($seq1, $seq2, $f))
@@ Line 156: / Line 156: @@
 </pre>
 * Another use-case: When inserting a key into a map, {{Code|$f}} decides how to combine the new value with a possibly existing old one. {{Code|hof:const}} here means ignoring the old value, so that's normal insertion.
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 let $insert-with := function($f, $map, $k, $v) {
    let $old := $map($k)

@@ Line 66: / Line 66: @@
+   )
 };
-</syntaxhighlight>
+</pre>
 |- valign="top"
 | '''Examples'''
@@ Line 73: / Line 73: @@
 <syntaxhighlight lang="xquery">
 hof:scan-left(1 to 10, 0, function($a, $b) { $a + $b })
-</syntaxhighlight>
+</pre>
 |}
@@ Line 96: / Line 96: @@
   return $item
 )[position() <= $k]
-</syntaxhighlight>
+</pre>
 |- valign="top"
 | '''Examples'''
@@ Line 154: / Line 154: @@
    $sum-left((1, 1, 1, 1, 1), 1 to 5)
+)
-</syntaxhighlight>
+</pre>
 * Another use-case: When inserting a key into a map, {{Code|$f}} decides how to combine the new value with a possibly existing old one. {{Code|hof:const}} here means ignoring the old value, so that's normal insertion.
 <syntaxhighlight lang="xquery">
@@ Line 169: / Line 169: @@
    $ins($map, 'foo', 42)('foo')
+)
-</syntaxhighlight>
+</pre>
 returns {{Code|3 42}}
 |}

← Older revision		Revision as of 08:47, 27 November 2023
Line 1:		Line 1:
	This [[Module Library\|XQuery Module]] adds some useful higher-order functions, additional to the [[Higher-Order Functions]] provided by the official specification.		This [[Module Library\|XQuery Module]] adds some useful higher-order functions, additional to the [[Higher-Order Functions]] provided by the official specification.
		+
		+	With {{Announce\|Version 11}}, many functions have been removed in favor of new features of XQuery 4:
		+
		+	{\|
		+	\|- valign="top"
		+	\| '''BaseX 10'''
		+	\| '''XQuery 4'''
		+	\|- valign="top"
		+	\| {{Code\|hof:drop-while}}
		+	\| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-drop-while <code>fn:items-starting-where</code>]
		+	\|- valign="top"
		+	\| {{Code\|hof:id}}
		+	\| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-identity <code>fn:identity</code>]
		+	\|- valign="top"
		+	\| {{Code\|hof:until}}
		+	\| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-iterate-while <code>fn:iterate-while</code>]
		+	\|- valign="top"
		+	\| {{Code\|hof:take-while}}
		+	\| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-take-while <code>fn:items-before</code>]
		+	\|}

	=Conventions=		=Conventions=

@@ Line 53: / Line 53: @@
 <syntaxhighlight lang="xquery">
 hof:scan-left(1 to 10, 0, function($a, $b) { $a + $b })
 </syntaxhighlight>
 |}
@@ Line 220: / Line 156: @@
 ;Version 11.0
-* Removed: {{Code|hof:until}} (replaced with {{Code|fn:iterate-while}}, {{Code|hof:if}} (replaced with {{Code|fn:identity}}
+* Removed: {{Code|hof:until}} (replaced with {{Code|fn:iterate-while}}, {{Code|hof:if}} (replaced with {{Code|fn:identity}}, {{Code|hof:drop-while}} (replaced with {{Code|fn:items-starting-where}}), {{Code|hof:take-while}} (replaced with {{Code|fn:items-before}})
 ;Version 9.5

@@ Line 168: / Line 168: @@
 * {{Code|hof:top-k-with(-5 to 5, function($a, $b) { abs($a) gt abs($b) }, 5)}} returns {{Code|0 1 -1 2 -2}}
 |}
 ==hof:const==

@@ Line 24: / Line 24: @@
 * {{Code|hof:fold-left1(1 to 10, function($a, $b) { $a + $b })}} returns {{Code|55}}.
 * {{Code|hof:fold-left1((), function($a, $b) { $a + $b })}} throws {{Code|XPTY0004}}, because {{Code|$seq}} has to be non-empty.
 |}
@@ Line 291: / Line 246: @@
 =Changelog=
 ;Version 9.5

@@ Line 173: / Line 173: @@
 | width='120' | '''Signature'''
 |<pre>hof:top-k-by(
-   $input  as item()*
+   $input  as item()*,
-   $key    as function(item()) as item()
+   $key    as function(item()) as item(),
    $k      as xs:integer
 ) as item()*</pre>
@@ Line 200: / Line 200: @@
 | width='120' | '''Signature'''
 |<pre>hof:top-k-with(
-   $input       as item()*
+   $input       as item()*,
-   $comparator  as function(item(), item()) as xs:boolean
+   $comparator  as function(item(), item()) as xs:boolean,
    $k           as xs:integer
 ) as item()*</pre>