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{{Built-in|Beside|∘}}, '''Compose''' or '''After''' is a [[primitive operator]]. It shares the glyph < | {{Built-in|Beside|∘}}, '''Compose''' or '''After''' is a [[primitive operator]]. It shares the glyph [[Jot]] (<syntaxhighlight lang=apl inline>∘</syntaxhighlight>) with [[Bind]]. Called [[Dyadic function|dyadically]] with function [[operand]]s <syntaxhighlight lang=apl inline>f</syntaxhighlight> and <syntaxhighlight lang=apl inline>g</syntaxhighlight>, it uses <syntaxhighlight lang=apl inline>g</syntaxhighlight> [[Monadic function|monadically]] to pre-processes the right argument before applying <syntaxhighlight lang=apl inline>f</syntaxhighlight> to the given left argument and pre-processed right argument. Called [[Monadic function|monadically]] with operands <syntaxhighlight lang=apl inline>f</syntaxhighlight> and <syntaxhighlight lang=apl inline>g</syntaxhighlight>, it applies <syntaxhighlight lang=apl inline>f</syntaxhighlight> to the result of applying <syntaxhighlight lang=apl inline>g</syntaxhighlight> to the argument. | ||
In usage, < | In usage, <syntaxhighlight lang=apl inline>X f∘g Y</syntaxhighlight> is equivalent to <syntaxhighlight lang=apl inline>X f g Y</syntaxhighlight>, and <syntaxhighlight lang=apl inline>f∘g Y</syntaxhighlight> is equivalent to <syntaxhighlight lang=apl inline>f g Y</syntaxhighlight>. Thus, beside can be defined as the [[dop]] <syntaxhighlight lang=apl inline>{⍺←⊢ ⋄ ⍺ ⍺⍺ ⍵⍵ ⍵}</syntaxhighlight>. | ||
== Examples == | |||
When used [[monadic]]ally, <syntaxhighlight lang=apl inline>f∘g</syntaxhighlight> behaves the same as an [[atop]]: | |||
<syntaxhighlight lang=apl> | |||
-∘÷ 2 | |||
¯0.5 | |||
⍝ same as | |||
-(÷2) | |||
¯0.5 | |||
</syntaxhighlight> | |||
When used [[dyadic]]ally, <syntaxhighlight lang=apl inline>f∘g</syntaxhighlight> forms a dyadic [[hook]]: | |||
<syntaxhighlight lang=apl> | |||
'oy'≡∘⌽'yo' | |||
1 | |||
⍝ same as | |||
'oy'≡⌽'yo' | |||
1 | |||
</syntaxhighlight> | |||
When used monadically with [[Commute]], <syntaxhighlight lang=apl inline>f∘g</syntaxhighlight> forms a monadic [[hook]]: | |||
<syntaxhighlight lang=apl> | |||
≡∘⌽⍨'UwU' | |||
1 | |||
⍝ same as this, because operators are left-associative, unlike functions which are right-associative | |||
(≡∘⌽)⍨'UwU' | |||
1 | |||
⍝ same as | |||
'UwU'≡⌽'UwU' | |||
1 | |||
</syntaxhighlight> | |||
== External links == | == External links == | ||
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=== Documentation === | === Documentation === | ||
* [ | * [https://help.dyalog.com/latest/#Language/Primitive%20Operators/Beside.htm Dyalog] | ||
{{APL built-ins}} | {{APL built-ins}}[[Category:Primitive operators]][[Category:Composition operators]] |