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In usage, <source lang=apl inline>X f∘g Y</source> is equivalent to <source lang=apl inline>X f g Y</source>, and <source lang=apl inline>f∘g Y</source> is equivalent to <source lang=apl inline>f g Y</source>. Thus, beside can be defined as the [[dop]] <source lang=apl inline>{⍺←⊢ ⋄ ⍺ ⍺⍺ ⍵⍵ ⍵}</source>. | In usage, <source lang=apl inline>X f∘g Y</source> is equivalent to <source lang=apl inline>X f g Y</source>, and <source lang=apl inline>f∘g Y</source> is equivalent to <source lang=apl inline>f g Y</source>. Thus, beside can be defined as the [[dop]] <source lang=apl inline>{⍺←⊢ ⋄ ⍺ ⍺⍺ ⍵⍵ ⍵}</source>. | ||
== Examples == | |||
When used [[monadic]]ally, <source lang=apl inline>f∘g</source> behaves the same as an [[atop]]: | |||
<source lang=apl> | |||
-∘÷ 2 | |||
¯0.5 | |||
⍝ same as | |||
-(÷2) | |||
¯0.5 | |||
</source> | |||
When used [[dyadic]]ally, <source lang=apl inline>f∘g</source> forms a dyadic [[hook]]: | |||
<source lang=apl> | |||
'oy'≡∘⌽'yo' | |||
1 | |||
⍝ same as | |||
'oy'≡⌽'yo' | |||
1 | |||
</source> | |||
When used monadically with [[Commute]], <source lang=apl inline>f∘g</source> forms a monadic [[hook]]: | |||
<source 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 | |||
</source> | |||
== External links == | == External links == | ||
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=== Documentation === | === Documentation === | ||
* [ | * [https://help.dyalog.com/18.0/#Language/Primitive%20Operators/Beside.htm Dyalog] | ||
{{APL built-ins}}[[Category:Primitive operators]] | {{APL built-ins}}[[Category:Primitive operators]][[Category:Composition operators]] |
Revision as of 10:18, 6 September 2021
∘
|
Beside (∘
), Compose or After is a primitive operator. It shares the glyph ∘
with Bind. Called dyadically with function operands f
and g
, it uses g
monadically to pre-processes the right argument before applying f
to the given left argument and pre-processed 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 left-associative, unlike functions which are right-associative (≡∘⌽)⍨'UwU' 1 ⍝ same as 'UwU'≡⌽'UwU' 1
External links
Lessons
Documentation