Typed function results and program errors

Purpose and scope

Separates a program's own outcome from successful engine execution. An error deliberately returned by user code is different from a parser or simulator failure.

Core design rules

• The entry function can return a value or symbolic error through a bounded Result<T, Error> contract.
• The payload of ok(...) must match the declared return type.
• Engine success and program outcome are reported separately; a program error is not labeled an engine failure.

Example from the original

This example illustrates the design recorded in the original. It is not by itself a claim of executable or stable support; check required options and the current version.

module typed_result;

fn main() -> Result<Int, Error> {
  let q = qreg[1];
  let measured: Bit = measure(q[0]);
  let encoded: Int = bit_to_int(measured);
  return ok(encoded);
}

Limits and interpretation

• Arbitrary exceptions, general error objects and unchecked return payloads are outside the scope.
• Result recovery in classical helpers does not automatically extend this historical entry-function slice.

Status and implementation boundary

The source describes a runtime-experimental result contract. Check NM-RFC-0035 and the corresponding guides for the boundaries of later helper-function additions.