Overview of Logical Operators¶

Logical operators combine conditions and produce BOOL values. Quxlang uses suffix operators for negation and for explicit presence tests.

Logical combinations¶

::may_enter FUNCTION(@has_key BOOL, @door_open BOOL): BOOL
{
  RETURN has_key && door_open;
}

ASSERT(may_enter(@has_key TRUE, @door_open TRUE));
ASSERT((may_enter(@has_key TRUE, @door_open FALSE) !!));

The common operators are && for and, || for or, ^^ for exclusive or, and suffix !! for negation. Quxlang additionally provides nand (!&), nor (!|), equivalence (!^), implication (^>), and reverse implication (^<).

Short-circuit evaluation¶

&& stops when its left operand is false, while || stops when its left operand is true. This is useful when the right operand is only valid after the left check succeeds:

IF (item?? && item-> > 0)
{
  item-> := item-> - 1;
}

Nand, nor, and the implication operators also skip the right operand whenever the left operand already determines the result. Exclusive-or and equivalence evaluate both operands.

Presence tests¶

value?? asks whether a supported value is present or nonzero. value!? asks the opposite.

VAR item ->I32;
ASSERT(item!?);

VAR storage I32 := 7;
item := storage<-;
ASSERT(item??);
ASSERT(item-> == 7);

Pointers use null versus non-null, integers use zero versus nonzero, interfaces use empty versus populated, and unions or variants use valueless versus holding an alternative.

Reference¶

See the Logical Operators Reference for the full truth-table meanings, evaluation rules, and supported presence tests.