Null

The null literal represents the absence of a value:

null

null is its own type. A variable declared without initialisation defaults to null:

var x          # x is null

Null equality

null is never equal to anything, including itself. Use is null / is not null to test for null:

null == null           # false
null != null           # true

var x = null
if x is null then
    # correct way to check for null
end

Truthiness

null is falsy. In boolean contexts (if, while, and/or/not) it behaves like false:

if null then
    # never runs
end

not null               # true
null or "fallback"     # "fallback"
null and "skipped"     # null

Null coalescing

The ?? operator returns the left operand if it is not null, otherwise the right operand:

var name = null ?? "Unknown"       # "Unknown"
var value = "hello" ?? "default"   # "hello"

Null in arithmetic

Using null with arithmetic operators (-, *, /, %) causes a runtime error because these operators require numeric operands. The + operator will concatenate null as the string "null" when the other operand is a string:

"value: " + null       # "value: null"