Seq and generators about expression HOT 4 CLOSED

The generator is not the problem. The problem is that your transform function takes two arguments. So you need to star the tuple argument:

ys = pipe(get_train_test_years(), seq.map(lambda x: transform(*x)))

But we should probably just add a starmap operator to the seq module:

def starmap(
    mapper: Callable[[Tuple[Any, ...]], Any]
) -> Callable[[Iterable[Any]], Iterable[Any]]:
    return seq.map(lambda x: mapper(*x))

from expression.

At

ys = pipe(get_train_test_years(), seq.map(lambda x: transform(*x)))

I get

(parameter) x: TSource@map
"object*" is not iterable
  "__iter__" method not definedPylance

from expression.

Yes, lambdas do not support type annotations. Use a function instead so you can specify the type of x e.g:

def mapper(x: Tuple[List[int], int]):
    return transform(*x)


ys = pipe(get_train_test_years(), seq.map(mapper))

PS: Also add type annotations to transform.

from expression.

Thanks for explaining this to me.

from expression.