wscript: pattern matching

match is an expression, exhaustiveness-checked at compile time; guards, or-patterns, if-let and let-else.

match is an expression, exhaustiveness-checked at compile time:

match e {
    Event::Quit => false,
    Event::Key(c) if c == 'q' => false,          // guards (don't count for exhaustiveness)
    Event::Key('h') | Event::Key('?') => help(), // or-patterns (no bindings inside, v1)
    Event::Key(_) => true,
    Event::Click { x, y } => x >= 0 && y >= 0,
}

if let Some(x) = opt { … } and let Some(n) = expr else { return Err("…") } work as in Rust (the let-else block must diverge).