def object_from_module(mod: ModuleType, pred: Callable[[Any], bool],
desc: str) -> Do:
all = yield Maybe.getattr(mod, '__all__').to_either(
f'module `{mod.__name__}` does not define `__all__`')
yield (Lists.wrap(all).flat_map(L(Maybe.getattr)(
mod,
_)).find(pred).to_either(f'no {desc} in `{mod.__name__}.__all__`'))
def type_arg(tpe: type, index: int) -> Do:
def error() -> str:
return f'{tpe} has no type args'
raw = yield Maybe.getattr(tpe, '__args__').to_either_f(error)
types = yield Right(Lists.wrap(raw)) if isinstance(
raw, Iterable) else Left(error())
yield types.lift(index).to_either_f(
lambda: f'{tpe} has less than {index + 1} args')
def objects_from_module(mod: ModuleType, pred: Callable[[Any], bool]) -> Do:
all = yield Maybe.getattr(mod, '__all__').to_either(
f'module `{mod.__name__}` does not define `__all__`')
return (Lists.wrap(all).flat_map(L(Maybe.getattr)(mod, _)).filter(pred))
def _dat__values(self) -> List[Any]:
return (self._dat__fields.traverse(
lambda a: Maybe.getattr(self, a.name),
Maybe).get_or_fail(lambda: f'corrupt `Dat`: {type(self)}'))
def list_type_decoder(ltpe: Type[Collection]) -> Do:
args = yield Maybe.getattr(ltpe, '__args__').map(Lists.wrap)
tpe = yield args.head
decoder = yield Decoder.m(tpe)
return tpe, decoder
