gnd

The bool operation produces a Boolean value. It accepts zero or one operand:

• No operand - shorthand for bool _. The current value of _ is evaluated.

• One operand - that value is evaluated and converted to either true or false.

Conversion rules - values are mapped to false only when they are “empty / zero”; everything else becomes true.

Operand type	Result is false when …	Otherwise
Boolean	the operand itself is false	true
Number (int / uint / float)	numeric value equals 0	true
String	length is 0	true
Array / Map	length is 0	true
null / none	always	-
Errors	always	-
Any other type	always	-

If the operand is missing or unrecognisable (for example, a malformed string literal that cannot be parsed at all), bool raises an error. The operation never mutates its input; it returns a fresh Boolean value.

Syntax

[ $destination ] bool [ value ]

• $destination is optional; if omitted, the Boolean result is stored in _.

• At most one operand may follow bool. Writing bool with no operand is equivalent to bool _.

Examples

Explicit literal:

$isReady bool true          # $isReady = true

Convert an integer:

$flag bool 0                # false
$flag bool 42               # true

Convert a string:

$empty let ""
$nonEmpty bool $empty       # false
bool "hello"                # true, result in _

Use the shorthand to convert the current _:

len [ ]                      # length 0 -> _ becomes 0
bool                         # converts 0 to false

Convert array length:

$items let ["a" "b"]
$has   bool $items          # true

bool always produces a single Boolean value, never changes existing variables, and respects Gendo’s single-assignment rule.