On 2016-11-09 07:19:04 -0800 (-0800), John Villalovos wrote: > Sort of related, what is the plan for supporting requirements which are > Python 3 only packages? > > In particular the package: mypy-lang > https://pypi.python.org/pypi/mypy-lang [...] If you only want mypy-lang installed when the interpreter is Python 3.3 or later (what their trove classifiers seem to imply for supported versions), use the following environment marker syntax: mypy-lang;python_version>='3.3' (see dnspython3 in global-requirements.txt for a similar example) https://pip.pypa.io/en/stable/reference/pip_install/#requirement-specifiers https://www.python.org/dev/peps/pep-0426/#environment-markers -- Jeremy Stanley