First: Difference between revisions

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|<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.