Behind {R}←{X}f⍛gY

Information

The ⍛ glyph is not available in Classic Edition, and the behind operator is instead represented by ⎕U235B.

f can be any monadic function that returns a result; the result must be suitable as the left argument to the function g.

g can be any dyadic function; it does not need to return a result.

Y can be any array that is suitable as the right argument to the function g. If X is omitted, Y must also be suitable as the right argument to the function f.

X can be any array that is suitable as the right argument to the function f.

The derived function is equivalent to either (f Y) g Y or (f X) g Y, depending on whether X is specified or not.

The behind operator allows functions to be glued together to build up more complex functions. For further information, see Function Composition.

Examples

      ⍝ Is it a palindrome?
      ⌽⍛≡ 'Dyalog' 
0
      ⌽⍛≡ 'racecar'
1

      ⍝ Drop from the right
      4-⍛↓'Dyalog APL'
Dyalog