Signature.__repr__ already exits. It is inherited from object. So you must be proposing to override the inherited method. For what purpose? With what outcome?

Without reading the signature PEP, I believe the current difference between str and repr is intentional, not accidental. Example:
>>> repr(s)
'<inspect.Signature object at 0x02E7BC08>'
>>> str(s)
'(self, a)'

If so, this issue should be closed unless you can provide an excellent reason to break code the expects the current behavior.

My impression is that the __repr__ method of any object is intended to describe that object, hopefully in a succinct way, possibly in a REPL-friendly way (like list.__repr__ for example) but if not then at least human-friendly. This is for easy introspection. When I come across a Signature object in the shell, I want to immediately get a good feel for what it contains without exploring vars(sig) manully.

If you have a Signature object, why not have its __repr__ return something like '<Signature f: alpha, beta=3, *args, **kwargs>`? This would do an awesome job at helping me understand what kind of signature object I'm looking at.

Ram, yes, I agree. Something like '<Signature f: alpha, beta=3, *args, **kwargs>' should work.

If you'd like to expand this issue's scope to all the objects related to Signature, I think that'll be good. All objects need good introspection strings.

New changeset 3f9a81297b39 by Yury Selivanov in branch 'default':
inspect.signature: Improve repr of Signature and Parameter. Closes bpo-20378
http://hg.python.org/cpython/rev/3f9a81297b39