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Miraheze>Adám Brudzewsky m (Adám Brudzewsky moved page Array prototype to Prototype over redirect: Merge with primitive function) |
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{{Built-ins|Prototype|∊|⊤}} is a [[monadic function]] which in the [[nested array model]] gives information about the type and structure of its argument array's [[element]]s. The result is derived from the first element of the array in [[ravel order]], or, if the array is [[Empty array|empty]], from information stored alongside the array (usually this information is just the prototype itself). An array's prototype is used as a [[fill element]] for operations involving that array, and to determine some [[identity element]]s. | |||
== Support== | |||
Few dialects have Prototype as a [[primitive function]]. [[Dyalog APL]] uses <source lang=apl inline>∊</source> (as in ''prototypical '''e'''lement''), but only when [[migration level]] is 0, while [[NARS2000]] uses [[monadic]] <source lang=apl inline>⊤</source> (resembling the Latin letter '''T''' for '''''T'''ype''). | |||
However, an arrays prototype can always be determined by enclosing the array in an empty array, and then coercing our a fill value. Since prototypes are used as fill elements, the resulting array will be the prototype of the original array: | |||
<source lang=apl> | |||
⊃ 0 ⍴ ⊂ 1 2 'ab' | |||
┌─┬─┬──┐ | |||
│0│0│ │ | |||
└─┴─┴──┘ | |||
</source> | |||
APLs with a [[flat array model]] do not typically store prototype information, instead using only the array's type ([[character]], [[numeric]], or [[Box|boxed]]) to determine its [[Fill element|fills]]. | APLs with a [[flat array model]] do not typically store prototype information, instead using only the array's type ([[character]], [[numeric]], or [[Box|boxed]]) to determine its [[Fill element|fills]]. | ||
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{{Works in|[[Dyalog APL]]}} | {{Works in|[[Dyalog APL]]}} | ||
{{APL programming language}} | {{APL programming language}} | ||
{{APL built-ins}} | |||