kw match

Reserved keyword

The list of words: §1.4

Syntax

Match       = "match" Expr "{" { Pattern [ "if" Expr ] "=>" Expr ( "," | NL ) } "}" ;

Grammar: App. A

Defined in

• 5.5 Pattern matching — A match MUST be exhaustive.
• 3.5 Unions and optionals — A | B — an anonymous union.
• 4.4 enum — A variant: without fields, with positional or with named fields.
• 5.1 General rules — Almost everything is an expression
• 5.4 Conditions — There is no ternary operator.
• 6.5 Errors — There are no exceptions.
• 1.4 Keywords — Reserved (cannot be used as names)

Examples

match result {
  Receipt r if r.amount > LIMIT => review(r)
  Receipt r                     => ok(r)
  Declined(reason)              => warn(reason)
  Timeout | Unavailable         => retryLater()
  _                             => fail Unknown
}

— 5.5 Pattern matching

Related diagnostics

non-exhaustive, pattern-bindings, unreachable-arm, type-mismatch, not-assignable, fail-type, question-context, unhandled-error