Operator Syntax

Operators take one or two operands. An operator with one operand is monadic. The operand of a monadic operator is to the left of the operator. An operator with two operands is dyadic. Both operands are required for a dyadic operator.

Operators have long scope to the left.  That is, the left operand is the longest function or array expression to its left (see Programmer's Guide: "Operators"). A dyadic operator has short scope on the right.  Right scope may be extended by the use of parentheses.

An operand may be an array, a primitive function, a system function, a defined function or a derived function. An array may be the result of an array expression.

An operator with its operand(s) forms a derived function. The derived function may be monadic or dyadic and it may or may not return an explicit result.

Examples

      +/⍳5
15
      (*∘2)⍳3
1 4 9

      PLUS ← + ⋄ TIMES ← ×
      1 PLUS.TIMES 2
2

Monadic Operators

Like primitive functions, monadic operators can be:

• named
• enclosed within parentheses
• displayed in the session

Examples

      ⎕ ← each ← (¨)      ⍝ name and display
¨
      shape←⍴
      shape each (1 2) (3 4 5)
 2  3 

      slash←/
      +slash ⍳10
55
      swap←⍨
      3 -swap 4
1

Right Operand Currying

A dyadic operator may be bound or curried with its right operand to form a monadic operator:

Examples

      ⎕ ← inv ← ⍣¯1  ⍝ produces monadic inverse operator
⍣ ¯1
      +\inv 1 2 3    ⍝ scan-inverse
1 1 1
      lim ← ⍣≡       ⍝ power-limit

      1 +∘÷lim 1     ⍝ Phi
1.61803