26
edits
Faun Locke (talk | contribs) m (Faun Locke moved page Split-compose to Split composition: Generalizing the topic) |
Faun Locke (talk | contribs) mNo edit summary |
||
Line 1: | Line 1: | ||
'''Split composition''' is a [[tacit]] pattern, used to pre-process argument(s) with the outer-most operands before applying the middle operand between the result. Given functions <syntaxhighlight lang=apl inline>f</syntaxhighlight>, <syntaxhighlight lang=apl inline>g</syntaxhighlight>, and <syntaxhighlight lang=apl inline>h</syntaxhighlight>, | '''Split composition''' is a [[tacit]] pattern, used to pre-process argument(s) with the outer-most operands before applying the middle operand between the result. Given functions <syntaxhighlight lang=apl inline>f</syntaxhighlight>, <syntaxhighlight lang=apl inline>g</syntaxhighlight>, and <syntaxhighlight lang=apl inline>h</syntaxhighlight>, a split composition on arguments <syntaxhighlight lang=apl inline>x</syntaxhighlight> and <syntaxhighlight lang=apl inline>y</syntaxhighlight> is defined as <syntaxhighlight lang=apl inline>(f x) g (h y)</syntaxhighlight>. | ||
This construct was introduced by the [[I|I language]] as "split-compose", where it is represented with <syntaxhighlight lang=apl inline>O</syntaxhighlight>. <syntaxhighlight lang=apl inline>O</syntaxhighlight> also represents the [[Over]] operator, as it is a split composition with identical outer operands. | This construct was introduced by the [[I|I language]] as "split-compose", where it is represented with <syntaxhighlight lang=apl inline>O</syntaxhighlight>. <syntaxhighlight lang=apl inline>O</syntaxhighlight> also represents the [[Over]] operator, as it is a split composition with identical outer operands. | ||
Line 18: | Line 18: | ||
== Alternatives == | == Alternatives == | ||
In dialects that lack Reverse Compose (and even Compose), split compositions can be denoted either by defining the missing operator(s), or as a single derived function or [[fork]], if this is supported. For example, in [[Dyalog APL]] the | In dialects that lack Reverse Compose (and even Compose), split compositions can be denoted either by defining the missing operator(s), or as a single derived function or [[fork]], if this is supported. For example, in [[Dyalog APL]] the pattern can be formed with Compose and [[Commute]] (<syntaxhighlight lang=apl inline>⍨</syntaxhighlight>) as <syntaxhighlight lang=apl inline>g⍨∘f⍨∘h</syntaxhighlight>: | ||
<syntaxhighlight lang=apl> | <syntaxhighlight lang=apl> | ||
5 ×⍨∘⍳⍨∘| 5 ¯8 ¯2 ¯5 3 | 5 ×⍨∘⍳⍨∘| 5 ¯8 ¯2 ¯5 3 |
edits