Skip to main content

Walrus Operator

The Walrus operator allows you to perform assignment expresssions, where the second operand to your assignment is the value of the expression.

Examples​

if a := get_value() then    -- 'a' was assigned a truthy value.else    -- 'a' was assigned a falsy value.end--> This code is semantically equal.local a = get_value()if a then    -- 'a' was assigned a truthy value.else    -- 'a' was assigned a falsy value.end

Expressions for the Walrus operator may be evaluated multiple times in circumstances like loops.

local function get()    return trueendwhile a := get() do    --> This will loop forever. It'll keep evaluating `a := get()`, just like any other condition.end

Like any other expression, you can also do things like this:

if (a := math.random(1, 10)) < 5 then    print("A is less than five! Value: " .. a)else    print("A is greater than five! Value: " .. a)end
  • The Walrus operator can be used anywhere an expression is accepted.
  • The Walrus operator does not support tuple assignment.

This feature is inspired from Python's implementation, which can be found here.