lib.types.coercedTo

The following is the current implementation of this function.

coercedTo =
        coercedType: coerceFunc: finalType:
        assert lib.assertMsg (
          coercedType.getSubModules == null
        ) "coercedTo: coercedType must not have submodules (it’s a ${coercedType.description})";
        mkOptionType rec {
          name = "coercedTo";
          description = "${optionDescriptionPhrase (class: class == "noun") finalType} or ${
            optionDescriptionPhrase (class: class == "noun") coercedType
          } convertible to it";
          check = x: (coercedType.check x && finalType.check (coerceFunc x)) || finalType.check x;
          merge =
            loc: defs:
            let
              coerceVal = val: if coercedType.check val then coerceFunc val else val;
            in
            finalType.merge loc (map (def: def // { value = coerceVal def.value; }) defs);
          emptyValue = finalType.emptyValue;
          getSubOptions = finalType.getSubOptions;
          getSubModules = finalType.getSubModules;
          substSubModules = m: coercedTo coercedType coerceFunc (finalType.substSubModules m);
          typeMerge = t: null;
          functor = (defaultFunctor name) // {
            wrappedDeprecationMessage = makeWrappedDeprecationMessage { elemType = finalType; };
          };
          nestedTypes.coercedType = coercedType;
          nestedTypes.finalType = finalType;
        };