Update project since mypy is introduced

[jxltom]

Since mypy in introduced in #51, this PR update requirements, add mypy to pipenv's scripts and update relevant .gitignore

It is blocked by #53 and #51 for now

[jxltom]

I'm curious why typed-ast, which is a dep of mypy and requires python3.3 or higher, needs markers manually? Why pipenv can not add markers automatically... 😕

[techalchemy]

Mypy itself doesn’t require markers does it? You just need typing; python_version<3.5

[jxltom]

Actually mypy required python 3.4+, otherwise pipenv will fail on locking

Check here https://github.com/python/mypy/blob/master/setup.py#L8-L10

[techalchemy]

Ah yeah. Anyway we considered cascading markers down. Now that we have a way to check reverse dependencies we can do that

[jxltom]

That will be great

[techalchemy]

Now do you see why i want --keep-outdated to respect things that used to be in the pipfile even if we can't find a parent for them anymore? This is a valid dependency!

[jxltom]

Indeed. But I'm curious why it is removed. I'm using python3 within the virtualenv and locking. Maybe you are using python2?

[techalchemy]

I generate and update with both versions typically to make sure I don’t have failing builds, which is why I focused on the use case of not removing dependencies that the resolver thinks are invalid

[jxltom]

Understood, feels the same now