Error using morphs in union types

[FrancescoLuzzi]

I'm trying to represent the following types:

const TestScope = scope({
  opts: {
    active: 'boolean',
    // the formats expected are ["en","it"] and "en|it", but I'd like to work with the former representation
    'translations?': type('string|string[]').pipe((s): string[] =>
      typeof s === 'string' ? s.split('|') : s
    )
  },
  file: {
    name: 'string',
    'opts?': 'opts'
  },
  module: {
    name: 'string',
    files: 'file[]'
  },
  package: {
    content: '(file|module)[]'
  }
}).export()

But i get the following error:

ParseError: An unordered union of a type including a morph and a type with overlapping input is indeterminate:
Left: { ext: string[], name: string, root: string, opts?: { active: boolean, translations?: (In: string | string[]) => Out<unknown> } }
Right: { files: { ext: string[], name: string, root: string, opts?: { active: boolean, translations?: (In: string | string[]) => Out<unknown> } }[], name: string }

I'm aware of the limitations of morphs, but I was curios if there's a workaround or a different approach that could work.
(different from defining 'translations?': "string|string[]", I'm trying to replace this definition)

Thanks 😄

[ssalbdivad]

The error here is essentially because if we get data that is a valid file and module like:

const data = {
  name: "foo",
  files: []
}

If you add something to one of the types so there's no way they could overlap, it should work, e.g.:

file: {
	name: "string",
	"opts?": "opts",
	"files?": "never"
},

That said, we should actually allow this case because its the same morph being applied in each branch. There's an open issue #1375 tracking an array edge case that would allow your original implementation to work.

[FrancescoLuzzi]

Thank you so much, i'll keep an eye on #1375!