widen (method)

widen

• widen<U, R>(): Opt<R>
• Experimental

  Widen union (typically union of strings to string).

  May be removed if it is later found out it's unsafe and unfixable.

  Type Parameters

  • U

  • R = SuperUnionOf<U, T>

  Returns Opt<R>

  Example

  type EnumAB = 'a' | 'b';
  type EnumABC = 'a' | 'b' | 'c';
  const ab = 'a' as EnumAB;
  const abc = 'c' as EnumABC;
  const correctWiden: Opt<EnumABC> = opt(ab).widen<EnumABC>(); // AB -> ABC: Ok
  const wrongWiden: Opt<never> = opt(abc).widen<EnumAB>(); // ABC -> AB: Not Ok, C is not in AB