[Python-ideas] A nice __repr__ for the ast.* classes?

[Haoyi Li]

Wouldn't it be nice if this

>>> import ast
>>> print repr(ast.parse("(1 + 1)").body[0].value)
<_ast.BinOp object at 0x0000000001E94B38>

printed something more useful?

>>> print repr(ast.parse("(1 + 1)").body[0].value)
BinOp(left=Num(n=1), op=Add(), right=Num(n=1))

I've been doing some work on macropy <https://github.com/lihaoyi/macropy>,
which uses the ast.* classes extensively, and it's annoying that we have to
resort to dirty-tricks like monkey-patching the AST classes (for CPython
2.7) or even monkey-patching __builtin__.repr (to get it working on PyPy)
just to get

    eval(repr(my_ast)) == my_ast

to hold true. And a perfectly good solution already exists in the
ast.dump() method, too! (It would also be nice if "==" did a structural
comparison on the ast.* classes too, but that's a different issue).

-Haoyi
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