Appendix B: Operators

This document lists ZuzuScript expression operators, ordered from highest precedence to lowest precedence.

Precedence summary table (highest to lowest)

Notes

  • Higher rows bind tighter than lower rows.
  • Most binary operators are left-associative.
  • ** is right-associative.
  • ⊤ and ⊥ are boolean literals, not operators, so they do not appear in the precedence table.
  • ?:, ? :, and assignment operators are parsed after the Pratt precedence table, so they behave as the lowest-precedence expression forms.
  • Postfix forms (call/member/index/dict access/postfix ++/--) are parsed immediately after primaries and therefore bind tighter than all infix operators.
Level Associativity Operators
Postfix left-to-right chaining (...) (call), .name, .(expr)(...), [index], [start:length], {key}, postfix ++, postfix --
Prefix right-to-left nesting unary +, unary -, !, ¬, unary ~, unary √, unary \\ (reference), not, abs, sqrt, floor, ceil, round, int, uc, lc, length, typeof, prefix ++, prefix --
13 right-to-left **
12 left-to-right *, /, ×, ÷, mod
11 left-to-right +, -
10 left-to-right _
9 left-to-right union, ⋃, intersection, ⋂, \\, ∖
8 left-to-right &
7 left-to-right ^
6 left-to-right |
5 left-to-right =, ≠, <, >, <=, ≤, >=, ≥, <=>, ≶, ≷, eq, ne, gt, ge, lt, le, cmp, eqi, nei, gti, gei, lti, lei, cmpi, in, ∈, ∉, subsetof, ⊂, supersetof, ⊃, equivalentof, ⊂⊃, instanceof, does, can, binary ~, @, @?, @@
4 left-to-right ==, ≡, !=, ≢
3 left-to-right and, ⋀, nand, ⊼
2 left-to-right xor, ⊻
1 left-to-right or, ⋁
Ternary right-to-left grouping in practice ? :, ?:
Assignment right-to-left grouping in practice :=, ~=, +=, -=, *=, ×=, /=, ÷=, **=, _=, ?:=

Detailed table

Operator Aliases Kind Precedence Definition
Mathematical operators and numeric comparisons
+ Unary prefix Numeric identity.
- Unary prefix Negative number.
√ sqrt Unary prefix Square root.
abs Unary prefix Absolute value.
floor Unary prefix Round down to the nearest integer.
ceil Unary prefix Round up to the nearest integer.
round Unary prefix Round to the nearest integer.
int Unary prefix Convert to an integer value.
** Binary infix 13 Exponentiation.
× * Binary infix 12 Multiplication.
÷ / Binary infix 12 Division.
mod Binary infix 12 Remainder after division.
+ Binary infix 11 Addition.
- Binary infix 11 Subtraction.
= Binary infix 5 Numeric equality.
≠ Binary infix 5 Numeric inequality.
< Binary infix 5 Less than.
> Binary infix 5 Greater than.
≤ <= Binary infix 5 Less than or equal to.
≥ >= Binary infix 5 Greater than or equal to.
≶ <=>, ≷ Binary infix 5 Numeric three-way comparison.
String operators and string comparisons
uc Unary prefix Uppercase string conversion.
lc Unary prefix Lowercase string conversion.
length Unary prefix String length.
_ Binary infix 10 String concatenation.
eq Binary infix 5 Case-sensitive string equality.
ne Binary infix 5 Case-sensitive string inequality.
gt Binary infix 5 Case-sensitive string greater-than comparison.
ge Binary infix 5 Case-sensitive string greater-than-or-equal comparison.
lt Binary infix 5 Case-sensitive string less-than comparison.
le Binary infix 5 Case-sensitive string less-than-or-equal comparison.
cmp Binary infix 5 Case-sensitive string three-way comparison.
eqi Binary infix 5 Case-insensitive string equality.
nei Binary infix 5 Case-insensitive string inequality.
gti Binary infix 5 Case-insensitive string greater-than comparison.
gei Binary infix 5 Case-insensitive string greater-than-or-equal comparison.
lti Binary infix 5 Case-insensitive string less-than comparison.
lei Binary infix 5 Case-insensitive string less-than-or-equal comparison.
cmpi Binary infix 5 Case-insensitive string three-way comparison.
~ Binary infix 5 Regexp match.
Bitwise operators
~ Unary prefix Bitwise NOT.
& Binary infix 8 Bitwise AND.
^ Binary infix 7 Bitwise XOR.
| Binary infix 6 Bitwise OR.
Logical operators
! Unary prefix Logical negation.
¬ not Unary prefix Logical negation.
⋀ and Binary infix 3 Logical AND.
⊼ nand Binary infix 3 Logical NAND.
⊻ xor Binary infix 2 Logical XOR.
⋁ or Binary infix 1 Logical OR.
Set operators and set comparisons
⋃ union Binary infix 9 Set union.
⋂ intersection Binary infix 9 Set intersection.
∖ \ Binary infix 9 Set difference.
∈ in Binary infix 5 Membership test using type-aware equality.
∉ Binary infix 5 Negative membership test.
⊂ subsetof Binary infix 5 Subset test.
⊃ supersetof Binary infix 5 Superset test.
⊂⊃ equivalentof Binary infix 5 Set equivalence test.
Path operators
@ Binary infix 5 Evaluate a path and return the first match.
@@ Binary infix 5 Evaluate a path and return all matches.
@? Binary infix 5 Check whether a path has at least one match.
OO / type related operators
typeof Unary prefix Return the runtime type name.
instanceof Binary infix 5 Inheritance-aware type or class check.
does Binary infix 5 Trait implementation check.
can Binary infix 5 Method availability check.
≡ == Binary infix 4 Type-aware equality.
≢ != Binary infix 4 Type-aware inequality.
Assignment operators
:= Assignment infix Assign a new value.
~= Assignment infix Regexp-replace assignment.
+= Assignment infix Add and assign.
-= Assignment infix Subtract and assign.
×= *= Assignment infix Multiply and assign.
÷= /= Assignment infix Divide and assign.
**= Assignment infix Exponentiate and assign.
_= Assignment infix Concatenate and assign.
?:= Assignment infix Assign only when the current value is undefined or null-like.
Other operators
++ Postfix Increment and return the previous value.
-- Postfix Decrement and return the previous value.
++ Unary prefix Increment and return the new value.
-- Unary prefix Decrement and return the new value.
\ Unary prefix Create an lvalue reference.
? : Ternary Conditional expression with true and false branches.
?: Ternary Elvis-style short ternary with a fallback value.

Ambiguous tokens by role

Some tokens are valid in more than one role:

  • ~ is both unary bitwise-not (prefix) and binary regexp-match.
  • \\ is both unary reference (prefix) and binary set difference.
  • + and - can be unary (prefix) or binary arithmetic.
  • ++ and -- can be prefix or postfix.

When mixing forms, parentheses are recommended for readability.

This matters especially for path lvalues. When applying prefix/postfix ++ or --, or unary reference \\, to data @ path, data @@ path, or data @? path, parenthesize the path expression:

( data @ "/meta/count" )++;
++ ( data @@ "/users/*/age" );
\( data @? "/meta/title" );