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{{BuiltinBeside∘}}, '''Compose''' or '''After''' is a [[primitive operator]]. It shares the glyph <  {{BuiltinBeside∘}}, '''Compose''' or '''After''' is a [[primitive operator]]. It shares the glyph [[Jot]] (<syntaxhighlight lang=apl inline>∘</syntaxhighlight>) with [[Bind]]. Called [[Dyadic functiondyadically]] 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 functionmonadically]] to preprocesses the right argument before applying <syntaxhighlight lang=apl inline>f</syntaxhighlight> to the given left argument and preprocessed right argument. Called [[Monadic functionmonadically]] 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 leftassociative, unlike functions which are rightassociative  
(≡∘⌽)⍨'UwU'  
1  
⍝ same as  
'UwU'≡⌽'UwU'  
1  
</syntaxhighlight>  
== External links ==  == External links ==  
Line 11:  Line 44:  
=== Documentation ===  === Documentation ===  
* [  * [https://help.dyalog.com/latest/#Language/Primitive%20Operators/Beside.htm Dyalog]  
{{APL builtins}}  {{APL builtins}}[[Category:Primitive operators]][[Category:Composition operators]] 
Latest revision as of 21:52, 10 September 2022
∘

Beside (∘
), Compose or After is a primitive operator. It shares the glyph Jot (∘
) with Bind. Called dyadically with function operands f
and g
, it uses g
monadically to preprocesses the right argument before applying f
to the given left argument and preprocessed right argument. Called monadically with operands f
and g
, it applies f
to the result of applying g
to the argument.
In usage, X f∘g Y
is equivalent to X f g Y
, and f∘g Y
is equivalent to f g Y
. Thus, beside can be defined as the dop {⍺←⊢ ⋄ ⍺ ⍺⍺ ⍵⍵ ⍵}
.
Examples
When used monadically, f∘g
behaves the same as an atop:
∘÷ 2
¯0.5
⍝ same as
(÷2)
¯0.5
When used dyadically, f∘g
forms a dyadic hook:
'oy'≡∘⌽'yo'
1
⍝ same as
'oy'≡⌽'yo'
1
When used monadically with Commute, f∘g
forms a monadic hook:
≡∘⌽⍨'UwU'
1
⍝ same as this, because operators are leftassociative, unlike functions which are rightassociative
(≡∘⌽)⍨'UwU'
1
⍝ same as
'UwU'≡⌽'UwU'
1
External links
Lessons
Documentation