Opine

• Opine Opine is an OCaml library that unparses the python AST produced by pyre-ast library back to python source code.

** Why would this be useful? I find this to be useful to do large scale python code transformations in OCaml.

** Can this be done in Python itself? Yes. But if you are looking for an OCaml library to do this, you probably already know why you are looking. Maybe this will help. I needed something like this to maintain python source code transformations.

** How it works? Fairly simple. The pyre-ast module provides a concrete AST representation of the python AST. The unparse module walks through the ast recursively while maintaining some state information and converts the AST back to python code. It doesn't use the visitor pattern. Everything is pure, simple functions.

** Example transformation If you wanted to add getters and setters to all the members in the class #+begin_src bash dune exec examples -- module test.py #+end_src *** Input file #+begin_src python class Sample(): def init(self, embed_dim, backend=None): self.embed_dim = embed_dim self.backend = backend

def forward(self, weight, value):
    return torch.bmm(weight, value)

#+end_src *** Output file #+begin_src python class Sample: def init(self, embed_dim, backend=None): self.embed_dim = embed_dim self.backend = backend

def forward(self, weight, value):
    return torch.bmm(weight, value)

@property
def embed_dim(self):
    return self._embed_dim

@property
def backend(self):
    return self._backend

@embed_dim.setter
def embed_dim(self, embed_dim):
    self._embed_dim = embed_dim

@backend.setter
def backend(self, backend):
    self._backend = backend

#+end_src ** How to run the unparser? Pass a python file or module as input and have it generate the python ast and back. #+begin_src bash dune exec bin/main.exe -- module expr.py #+end_src

** Credits This library exists because of [[https://github.com/grievejia/pyre-ast][pyre-ast]]