Grammar
The exact grammar can be read from the source code at grammar.pest. Because it is a functional language it consists only of expressions, no statements.
It supports
- groups for precedence (
(...)), - binary and unary operators (
and,not,!, etc.), - functions (
func(a, b, c)), - patterns (
r:^foo), - and basic data types like strings (
"...",'...') and numbers (1,1_000).
Operators
The following operators are available:
| Type | Prec. | Name | Symbols | Explanation |
|---|---|---|---|---|
| infix | 1 | union | | , or | Includes all tests which are in either the left OR right test set expression. |
| infix | 1 | difference | ~, diff | Includes all tests which are in the left but NOT in the right test set expression. |
| infix | 2 | intersection | &, and | Includes all tests which are in both the left AND right test set expression. |
| infix | 3 | symmetric difference | ^, xor | Includes all tests which are in either the left OR right test set expression, but NOT in both. |
| prefix | 4 | complement | !, not | Includes all tests which are NOT in the test set expression. |
Be aware of precedence when combining different operators, higher precedence means operators bind more strongly, e.g. not a and b is (not a) and b, not not (a and b) because not has a higher precedence than and.
Binary operators are left associative, e.g. a ~ b ~ c is (a ~ b) ~ c, not a ~ (b ~ c).
When in doubt, use parentheses to force the precedence of expressions.