Compose

In the following descriptions, f and g represent functions and a and b represent variables.

• The form f∘g may be used both monadically and dyadically.

Monadic: Z←f∘gR is identical to Z←fgR.

Dyadic: Z←Lf∘gR is identical to Z←LfgR.

• The form f∘b may be used monadically only.

Monadic: Z←(f∘b) R is identical to Z←R f b.

Note that parentheses are required around the function to avoid interpreting b R as a strand.

• The form a∘g may be used monadically only.

Monadic: Z←a∘gR is identical to Z←a g R.

• The derived function from the form a∘b always signals a SYNTAX ERROR.

Compose can be useful for function assignment (but enclosing parentheses are necessary).
For example
      p1←(1∘+¯2∘π) ⍝ 1 more than the Nth prime number
      p1 ⍳9
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