Match for scalar values

match compares a value against a list of patterns and hands back a value — think switch, but as an expression, with no fallthrough and no break. Each arm is pattern -> result, and else is the catch-all for “everything not listed above” (there’s no cryptic _).

fix roll = 3;
fix prize = match roll {
  1 -> "gold",
  2 -> "silver",
  3 -> "bronze",
  else -> "no prize",
};
prize

fix roll = 3;
fix prize = match roll {
  1 -> "gold",
  2 -> "silver",
  3 -> "bronze",
  else -> "no prize",
};
prize

The subject is parenthesized nowhere — just match value { ... } — and because it’s an expression, you bind its result straight to a slot.

The one rule switch never enforced: a match must cover every possible value. There are infinitely many Ints, so a scalar match can’t list them all — which means you need that else. Leave it off and Ascent flags the gap on the spot, with Run greyed out until you close it:

fix code = 2;
match code {
  1 -> "start",
  2 -> "stop",
}

fix code = 2;
match code {
  1 -> "start",
  2 -> "stop",
}

Add an else arm above so the match handles the values you didn’t name, and it’ll run. You can’t forget a case here — the compiler won’t let you.

These patterns are shallow for now: plain literals and else, nothing more. Matching over your own types, with fields pulled out of each case, comes once you’ve built some types of your own.