Internal documentation — Work in progress

This page has not been confirmed as accurate or approved for publication. Current documentation version: 0.1.0-internal.1.

Control flow

The parser implements if, else, for, in, while, until, break, continue, return, match, and case. The tokenizer also reserves yield for a later milestone.

for item in items {
  if item.invalid {
    continue
  }
  while item.pending {
    item.poll()
    if item.failed {
      break
    }
  }
}

until simulation.complete {
  simulation.step!()
}

return simulation.result

break and continue are unlabeled and valid only inside a loop. A return may carry an expression or stand alone to return without a value.

A match statement contains one or more block-bodied cases:

match simulation.status {
  case "ready" {
    simulation.run!()
  }
  case expected_status {
    simulation.prepare!()
  }
  case else {
    simulation.wait!()
  }
}

case else is optional, unique, and must be last. The parser accepts expression-shaped case patterns. Whether an identifier denotes a value, binds a new name, or participates in destructuring will be decided by semantic analysis.

Settled design: and, or, not, and ! provide logical operations. A conditional expression uses ? and ;:

let status = active ? "running" ; "stopped"

Newlines normally terminate statements; ; is not an ordinary statement terminator. The tokenizer already suppresses newlines inside parentheses and brackets and after tokens that leave an expression incomplete.

Provisional design: match-pattern meaning and exhaustiveness, iteration protocols, yield semantics, unreachable-code analysis, and the runtime meaning of returned values.