Operator Definition

operator statement defines a custom operator and its precedence and associativity. The implementation of the operator is defined separately using the operator function statement.

Specifications

infix operators take two operands on both sides, prefix operators take a single operand on the right, and postfix operators take a single operand on the left.

Precedence determines the order of evaluation when multiple operators appear in an expression. A higher precedence value means the operator binds more tightly.

Associativity determines how operators of the same precedence are grouped. left groups from the left, right groups from the right, and none disallows chaining operators of the same precedence. Prefix and postfix operators do not have associativity.

Syntax

operator infix <Symbol> {
    precedence: <Precedence>,
    associativity: <Associativity>
}

operator prefix <Symbol> {
    precedence: <Precedence>
}

operator postfix <Symbol> {
    precedence: <Precedence>
}

Example

This example program defines a custom operator ** and declares its implementation for Float using operator function statement.

import std

operator infix ** {
    precedence: 95,
    associativity: right
}

func infix **(lhs: Float, rhs: Float) -> Float {
    return std.float.pow(lhs, rhs)
}

func main() {
    let square = 5.0 ** 2.0
}