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{ | {| class=vertical-navbox style="float:right; font-size:500%; margin:0 1ex;" | ||
|<code>∊</code> <code>⊤</code> <code>⍷</code> | |||
|} | |||
'''Type''' (<code>∊</code>, <code>⊤</code>, <code>⍷</code>) is a [[monadic]] [[scalar function]] which in the [[nested array model]] gives information about the type and structure of its argument array's [[element]]s. In normal cases, the result is identical to the argument, with all numbers replaced by zeros and all characters replaced by spaces, and the substitution is done recursively. | |||
== Support== | == Support== | ||
Few dialects have Type as a [[primitive function]]. [[Dyalog APL]] | Few dialects have Type as a [[primitive function]]. [[APL2]] IUP had it,<ref>Graham, Alan. [https://dl.acm.org/doi/pdf/10.1145/22008.22033#page=4 Idioms and Problem Solving Techniques in APL2; Appendix - APL2 Idiom List: 9. Type]. [[APL86]].</ref> and thus [[Dyalog APL]] originally supported it too. However, by the time [[IBM]] released APL2, <syntaxhighlight lang=apl inline>∊</syntaxhighlight> (as in ''prototypical '''e'''lement'') was repurposed for [[Enlist]]. Thus, Dyalog left the Type meaning in place only when [[migration level]] is 0, while setting it to 1 or higher follows IBM's replacement meaning. [[NARS2000]] uses [[monadic]] <syntaxhighlight lang=apl inline>⊤</syntaxhighlight> (resembling the Latin letter '''T''' for '''''T'''ype''), which it inherited from [[NARS]]. [[Extended Dyalog APL]] uses monadic <syntaxhighlight lang=apl inline>⍷</syntaxhighlight> with the underscore indicating functionality of the corresponding non-underscored glyph from a non-default migration level.<ref>[[Partition]] is <syntaxhighlight lang=apl inline>⊆</syntaxhighlight> with migration level≤2 while the original glyph is <syntaxhighlight lang=apl inline>⊂</syntaxhighlight> as with migration level 3. Dyalog Language Reference Guide: [https://help.dyalog.com/latest/#Language/Symbols/Left%20Shoe.htm Left Shoe].</ref> | ||
However, in all dialects that support nested arrays, the type can be determined by enclosing/boxing the array in an empty array, and then coercing out a fill value. Since the [[array prototype]] is used as fill element, the resulting array will be the type of the original array: | However, in all dialects that support nested arrays, the type can be determined by enclosing/boxing the array in an empty array, and then coercing out a fill value. Since the [[array prototype]] is used as fill element, the resulting array will be the type of the original array: | ||
< | <syntaxhighlight lang=apl> | ||
↑ 0 ⍴ ⊂ 1 2 'ab' | ↑ 0 ⍴ ⊂ 1 2 'ab' | ||
┌─┬─┬──┐ | ┌─┬─┬──┐ | ||
│0│0│ │ | │0│0│ │ | ||
└─┴─┴──┘ | └─┴─┴──┘ | ||
</ | </syntaxhighlight> | ||
{{Works in|[[Dyalog APL]] with [[migration level]]≥2, [[APL2]], [[APLX]]}} | {{Works in|[[Dyalog APL]] with [[migration level]]≥2, [[APL2]], [[APLX]]}} | ||
< | <syntaxhighlight lang=apl> | ||
⊃ 0 ⍴ ⊂ 1 2 'ab' | ⊃ 0 ⍴ ⊂ 1 2 'ab' | ||
┌─┬─┬──┐ | ┌─┬─┬──┐ | ||
│0│0│ │ | │0│0│ │ | ||
└─┴─┴──┘ | └─┴─┴──┘ | ||
</ | </syntaxhighlight> | ||
{{Works in|[[Dyalog APL]] with [[migration level]]<nowiki>=</nowiki>1}} | {{Works in|[[Dyalog APL]] with [[migration level]]<nowiki>=</nowiki>1}} | ||
{{APL built-ins}} | == External links == | ||
=== Documentation === | |||
* [https://help.dyalog.com/latest/#Language/Primitive%20Functions/Type.htm Dyalog] | |||
== References == | |||
<references/> | |||
{{APL built-ins}}[[Category:Primitive functions]][[Category:Scalar monadic functions]] | |||