Match block

A match expression allows to branch by pattern on an expression.

Syntax

match_expression
  = "match" expression
  "{" pattern_matching_clause ("," pattern_matching_clause)* ","? "}"

Example

match result {
  (@ok) -> {
    # ...
  },
  (@error) -> {
    # ...
  },
};

Semantics

A match expression MUST evaluate to the value the matching clause evaluates to.

If no clause matches, and exception MUST be thrown, the value of that exception is defined by the implementation:

match 42 {
  (41) -> @ok,
};

# is equivalent to:

match 42 {
  (41) -> @ok,
  (_) -> throw @implementation_defined_error,
};