For those asking "who uses PyPy?": the truth is that very few people using it get back to us and say how it helps them or what they are doing with it. For instance crossbar.io uses it [0]. Some shops use it as a second step until they refactor code into a compiled language, but often that second step never materializes.
But the value of a second implementation of a language goes beyond the immediate "who uses this in practice". It can be a fertile bed for innovation and for new ideas, and provides a contrast to the nay sayers. For instance, the recent pitch to vastly improve CPython's speed has some roots in ideas that were tested out in PyPy. CFFI [1], revdb [2] and vmprof [3] all started as PyPy projects. Some of these turned out to be very popular, some less so. The next project in this line is HPy [4] (still alpha-quality), which is trying to re-think the C-API for Python to make it even easier to interface with.
RPython [5], the language behind PyPy, is also an accessible playground for dynamic language research.
But the value of a second implementation of a language goes beyond the immediate "who uses this in practice". It can be a fertile bed for innovation and for new ideas, and provides a contrast to the nay sayers. For instance, the recent pitch to vastly improve CPython's speed has some roots in ideas that were tested out in PyPy. CFFI [1], revdb [2] and vmprof [3] all started as PyPy projects. Some of these turned out to be very popular, some less so. The next project in this line is HPy [4] (still alpha-quality), which is trying to re-think the C-API for Python to make it even easier to interface with.
RPython [5], the language behind PyPy, is also an accessible playground for dynamic language research.
[0] https://crossbar.io/about/FAQ/#python-runtime
[1] https://cffi.readthedocs.io/en/latest/
[2] https://morepypy.blogspot.com/2016/07/reverse-debugging-for-...
[3] https://vmprof.readthedocs.io/en/latest/
[4] https://hpy.readthedocs.io/en/latest/
[5] https://rpython.readthedocs.io/en/latest/examples.html