Operators
- Operator Precedence
- Mathematical Operators
- Equality & Comparison Operators
- Logical Operators
- The Conditional Operator
- The Null-coalescing Operator
- The Error-coalescing Operator
Operator Precedence
Operator precedence in the table below goes from high at the top to low at the bottom. Operators at the same level have the same precedence.
| Level | Operators | Associativity |
|---|---|---|
| Call |
() . : ::
|
Left |
| Power |
**
|
Right |
| Unary |
! + - ~ try
|
Right |
| Bitwise |
& | ^ >> <<
|
Left |
| Multiplication |
* / // %
|
Left |
| Addition |
+ -
|
Left |
| Comparison |
> >= < <=
|
Left |
| Equality |
== !=
|
Left |
| Logical |
&& || ?? !!
|
Left |
| Conditional |
? :|
|
None |
| Assignment |
= += -=
|
Right |
Note that conditional expressions using the ternary operator ? :| can't be nested. (Checkmate, Satan.)
Mathematical Operators
| + | Addition (binary) or a no op (unary). Addition returns an integer if both operands are integers or a float if either or both are floats. |
| - | Subtraction (binary) or negation (unary). Subtraction returns an integer if both operands are integers or a float if either or both are floats. |
| * | Multiplication. Returns an integer if both operands are integers or a float if either or both are floats. |
| / | Floating-point division. Both operands will be converted to floats and the result will be a float. |
| // | Truncating division. Returns an integer if both operands are integers or a float if either or both are floats. |
| % | Modulo/remainder operator. Returns an integer if both operands are integers or a float if either or both are floats. |
| ** | Power operator. Both operands are converted to floats and the result is a float. |
You can overload the mathematical operators to customize their behaviour for your own types.
Equality & Comparison Operators
The equality (==, !=) and comparison (>, >=, <, <=) operators each take two operands and evaluate to a boolean.
- Numbers are equal if their values are numerically equal.
- Strings are equal if they have the same content.
- Tuples are equal if they have the same length and their elements are equal.
- By default, other objects are equal only if they are the same object.
Logical Operators
The logical operators are || (OR), && (AND), and ! (NOT). They evaluate the truthiness of their operands.
The logical operators || and && are short-circuiting.
The value of the logical-OR expression a || b is the value of the first operand if that operand is truthy, otherwise the value of the second operand.
This means you can use the || operator to swap in a default value in place of a falsey expression:
var foo = maybe_falsey() || "default";
The value of the logical-AND expression a && b is the value of the first operand if that operand is falsey, otherwise the value of the second operand.
This means you can use the && operator to conditionally chain a sequence of expressions:
func1() && func2() && func3();
func2() will only be called if func1() returns a truthy value; func3() will only be called if func2() returns a truthy value.
The Conditional Operator
The conditional or ternary operator takes three operands. It looks like this:
var foo = condition ? expr1 :| expr2;
The value of the expression is expr1 if condition evaluates as truthy, otherwise expr2.
The Null-coalescing Operator
The null-coalescing operator ?? lets you swap in a default value in place of a null:
var foo = maybe_null() ?? "default";
The value of the expression a ?? b is the value of the first operand if that operand is not null, otherwise the value of the second operand.
The Error-coalescing Operator
The error-coalescing operator !! lets you swap in a default value in place of an error:
var foo = maybe_error() !! "default";
The value of the expression a !! b is the value of the first operand if that operand is not an $err, otherwise the value of the second operand.