Optional fields pattern matching: untagged variants

[cristianoc]

Add support for untagged variants to optimised pattern matching for optional fields.

[cknitt]

👍 For reference, what would the output for the new example have looked like before this change?

And interesting - why is it checking for id === null, but not for name === null?

Is it possible to further simplify to something like

function decodeGroup(group) {
  let id = group.id;
  let name = group.name;

  if (typeof id !== "string" || typeof name !== "string") {
    return [
      "e",
      "f"
    ];
  } else {
    return [
      id,
      name
    ];
  }
}

[cristianoc]

👍 For reference, what would the output for the new example have looked like before this change?

And interesting - why is it checking for id === null, but not for name === null?

Is it possible to further simplify to something like

function decodeGroup(group) {
  let id = group.id;
  let name = group.name;

  if (typeof id !== "string" || typeof name !== "string") {
    return [
      "e",
      "f"
    ];
  } else {
    return [
      id,
      name
    ];
  }
}

Same answer to both: it's an artifact the pattern matching algorithm.
Which hasn't changed yet, but will in #7135