Welcome to PyPy!

PyPy is both an implementation of the Python programming language, and an extensive compiler framework for dynamic language implementations. You can build self-contained Python implementations which execute independently from CPython.

The home page is:

http://pypy.org/

If you want to help developing PyPy, this document might help you:

http://doc.pypy.org/

It will also point you to the rest of the documentation which is generated from files in the pypy/doc directory within the source repositories. Enjoy and send us feedback!

the pypy-dev team <pypy-dev@python.org>

First switch to or download the correct branch. The basic choices are default for Python 2.7 and, for Python 3.X, the corresponding py3.X branch (e.g. py3.5).

Build with:

$ rpython/bin/rpython -Ojit pypy/goal/targetpypystandalone.py

This ends up with a pypy-c or pypy3-c binary in the main pypy directory. We suggest to use virtualenv with the resulting pypy-c/pypy3-c as the interpreter; you can find more details about various installation schemes here:

http://doc.pypy.org/en/latest/install.html

http://eli.thegreenplace.net/2010/06/30/python-internals-adding-a-new-statement-to-python/

http://hirzels.com/martin/papers/dls12-thorn-patterns.pdf

http://doc.pypy.org/en/latest/getting-started-dev.html?highlight=grammar

Patterns: 1. check whether a given input has certain "structure" 2. extract the pieces or no piece 3. can optionally bind pieces to variables that can be used later

Some Use Cases (may not be the same syntax) =============== If none of the cases matches, it will throw an exception. We may want match to be an expression but not a statement.

def haha(arg):

x = match(arg):

with 1 or 2:

3

with 3:

7

with y : Int:

2

with _:

throws Exception("Not an Int")

return x

def yosh(arg):

x = match(arg):

with []:

[3]

with {}:

{3}

with _:

print "nima" None

return x

More use cases of match:

x = match(L):

[x : str , y : str, x[::-1]]:

x + y

_:

"Wrong"

y = match(L):

[_ : int, _ : int, _ : int]:

...

_:

...

Problems of Expression vs. Statement:

If we make match a expression, it would include indentations inside the expression, which is not normal and intuitive for python, and not sure if it is even possible. However, it is definetly more powerful than just a statement.