Classic Edition: the symbol ⍥ is not available in Classic Edition, and the Over operator is instead represented by ⎕U2365.

g can be any monadic function which returns a result. Y can be any array that is suitable as the argument to function g with gY being suitable as the right argument to function f.

If X is omitted, f must be a monadic function. If X is specified, f must be a dyadic function and X can be any array that is suitable as argument to function g with gX being suitable as the left argument to function f.

The derived function is equivalent to fgY or (gX)f(gY) and need not return a result.

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

      2 3 ,⍥⊂ 'text'   ⍝ ,⍥⊂  ←→  {⍺⍵}
┌───┬────┐
│2 3│text│
└───┴────┘
 
     scores←82 90 76
     weights←20 35 45
     (weights×scores)÷⍥(+/)weights ⍝ Weighted average
82.1