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|<code>⊃</code> <code>↑</code> | |<code>⊃</code> <code>↑</code> | ||
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'''First''' (<code>⊃</code> or <code>↑</code> and also called '''Disclose''') is a [[monadic function]] in [[Nested array model|nested]] APLs which extracts the first [[element]] in [[ravel order]] from its argument, or, if the argument is [[empty]], returns its [[prototype]]. The [[glyph]] used varies by dialect. In a [[Nested array model|nested]] APL, First reduces the positive [[depth]] of an argument other than a [[simple scalar]] by at least one; in a [[Flat array model|flat]] APL it does not change the depth. A flat array language may also use the [[Head]] function to get the first [[major cell]] of its argument rather than the first 0-[[cell]]. In this case First can be obtained by [[take|taking]] the Head of the [[Ravel]] of the argument. | '''First''' (<code>⊃</code> or <code>↑</code> and also called '''[[Disclose]]''') is a [[monadic function]] in [[Nested array model|nested]] APLs which extracts the first [[element]] in [[ravel order]] from its argument, or, if the argument is [[empty]], returns its [[prototype]]. The [[glyph]] used varies by dialect. In a [[Nested array model|nested]] APL, First reduces the positive [[depth]] of an argument other than a [[simple scalar]] by at least one; in a [[Flat array model|flat]] APL it does not change the depth. A flat array language may also use the [[Head]] function to get the first [[major cell]] of its argument rather than the first 0-[[cell]]. In this case First can be obtained by [[take|taking]] the Head of the [[Ravel]] of the argument. | ||
== External links == | == External links == | ||
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== See also == | == See also == | ||
* [[Mix]] | * [[Mix]] | ||
* [[Right Shoe]] | * [[Right Shoe]] | ||
{{APL built-ins}}[[Category:Primitive functions]] | {{APL built-ins}}[[Category:Primitive functions]] | ||
Revision as of 17:50, 26 October 2020
⊃ ↑
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First (⊃ or ↑ and also called Disclose) is a monadic function in nested APLs which extracts the first element in ravel order from its argument, or, if the argument is empty, returns its prototype. The glyph used varies by dialect. In a nested APL, First reduces the positive depth of an argument other than a simple scalar by at least one; in a flat APL it does not change the depth. A flat array language may also use the Head function to get the first major cell of its argument rather than the first 0-cell. In this case First can be obtained by taking the Head of the Ravel of the argument.