⍨
f⍨Y is Y f Y.
f⍨Y
Y f Y
×⍨3 ⍝ 9
X f⍨Y is Y f X.
X f⍨Y
Y f X
2-⍨10 ⍝ 8
An array operand makes a constant function: A⍨Y and X A⍨Y return A.
A⍨Y
X A⍨Y
A
42⍨0 ⍝ 42