Passing a type as the first argument of map

[cjolowicz]

The following expression should type-check fine, right?

map(list, [{1}])

The intended use is to convert (iterables of) sets to (iterables of) lists, e.g. to support slicing.

I'm getting this error:

main.py:1: error: Argument 1 to "map" has incompatible type "Type[List[Any]]"; expected "Callable[[Set[int]], List[_T]]"
Found 1 error in 1 file (checked 1 source file)

This issue seems related to #3092.

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[msullivan]

It looks like there are a bunch of bugs having to do with using types as functions in generic situations.

[pcworld]

As a workaround, the following passes with Python 3.9: map(list[int], [{1}])
On earlier Python versions, the following works: map(lambda i: list(i), [{1}])

[ilevkivskyi]

This now works properly (most likely by polymorphic inference).