Pair: Difference between revisions

{{Built-in|Pair|⍮}} or '''Juxtapose''' is a [[primitive]] [[ambivalent function]] that constructs a [[vector]] of its [[argument]]s. It can be implemented as the [[dfn]] <syntaxhighlight lang=apl inline>{⍺←,⊂ ⋄ ⍺ ⍵}</syntaxhighlight>, or the [[catenate|catenation]] of the [[enclose]]d arguments, written <syntaxhighlight lang=apl inline>,⍥⊂</syntaxhighlight> using [[Over]].<ref>[https://www.jsoftware.com/papers/satn41.htm "Composition and Enclosure"] § Composition Operators. SATN-41, 1981-06-20.</ref> Pair aids in constructing nested arrays in [[tacit programming]], where [[stranding]] by juxtaposition is not available. It was introduced in [[Extended Dyalog APL]] in 2018, and then adopted into [[dzaima/APL]]. It was added to [[BQN]] with the glyph <code>⋈</code> in 2021. The [[monadic]] case, which is similar to [[Enclose]] except that it gives a result of [[rank]] 1 rather than 0, is called '''Enlist''' in BQN, as well as [[K]], where it is the monadic case of <code>,</code> (K has no dyadic Pair primitive).