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Uses and additional types
Miraheze>Adám Brudzewsky (Created page with "{{Built-ins|Type|∊|⊤}} is a monadic function which in the nested array model gives information about the type and structure of its argument array's elements. I...") |
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|<code>∊</code> <code>⊤</code> <code>⍷</code> | |||
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'''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│0│ │ | │0│0│ │ | ||
└─┴─┴──┘ | └─┴─┴──┘ | ||
</ | </syntaxhighlight> | ||
{{Works in|[[Dyalog APL]] with [[migration level]] | {{Works in|[[Dyalog APL]] with [[migration level]]≥2, [[APL2]], [[APLX]]}} | ||
< | <syntaxhighlight lang=apl> | ||
⊃ 0 ⍴ ⊂ 1 2 'ab' | |||
┌─┬─┬──┐ | ┌─┬─┬──┐ | ||
│0│0│ │ | │0│0│ │ | ||
└─┴─┴──┘ | └─┴─┴──┘ | ||
</ | </syntaxhighlight> | ||
{{Works in|[[Dyalog APL]] with [[migration level]] | {{Works in|[[Dyalog APL]] with [[migration level]]<nowiki>=</nowiki>1}} | ||
=== Additional types === | |||
Dyalog APL has additional data types, besides for the traditional numeric, character, and nested ones. [[Null]]s and [[Object Representation]]s are their own type, while instances of objects with [[niladic]] constructor (or no constructors) cause the creation of new instances of the same class. Other objects, namely [[namespace]]s and classes with constructors but no niladic constructor, cause a [[NONCE ERROR]]. | |||
== Examples == | |||
Type can be used to construct universal utilities that adapt to the type of data given as argument. For example: | |||
<syntaxhighlight lang=apl> | |||
Null ← ≡∘∊⍨ ⍝ Indicate empty or all blank and/or zero | |||
Nil ← ∊∘∊⍨ ⍝ Indicates null items | |||
Clean ← ~∘∊⍨ ⍝ Without null items | |||
Split ← (⊢⊆⍨∊≢¨⊢) ⍝ Split on null items | |||
data ← 'Hello' ' ' 'World' ⎕NULL (2 7 1 8) (3 1 4 1 5) (0 0 0) (0 0 7) | |||
Null 2⊃data | |||
1 | |||
Null 3⊃data | |||
0 | |||
Nil data | |||
0 1 0 1 0 0 1 0 | |||
Clean data | |||
┌─────┬─────┬───────┬─────────┬─────┐ | |||
│Hello│World│2 7 1 8│3 1 4 1 5│0 0 7│ | |||
└─────┴─────┴───────┴─────────┴─────┘ | |||
Split data | |||
┌───────┬───────┬───────────────────┬───────┐ | |||
│┌─────┐│┌─────┐│┌───────┬─────────┐│┌─────┐│ | |||
││Hello│││World│││2 7 1 8│3 1 4 1 5│││0 0 7││ | |||
│└─────┘│└─────┘│└───────┴─────────┘│└─────┘│ | |||
└───────┴───────┴───────────────────┴───────┘ | |||
</syntaxhighlight> | |||
{{Works in|[[Dyalog APL]] with [[migration level]]<nowiki>=</nowiki>0}} | |||
{{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]] | |||