Beside
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∘

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 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