On 20 December 2014 at 10:55, Guido van Rossum
A few months ago we had a long discussion about type hinting. I've thought a lot more about this. I've written up what I think is a decent "theory" document -- writing it down like this certainly helped *me* get a lot of clarity about some of the important issues.
I should thank Jeremy Siek for his blog post about Gradual Typing, Jukka Lehtosalo for mypy (whose notation I am mostly borrowing), and Jim Baker for pushing for an in-person meeting where we all got a better understanding of several issues.
There's also a PEP draft, written by Łukasz Langa and revised by him based on notes from the above-mentioned in-person meeting; unfortunately it is still a bit out of date and I didn't have time to update it yet. Instead of working on the PEP, I tried to implement a conforming version of typing.py, for which I also ran out of time -- then I decided to just write up an explanation of the theory.
This looks like a great direction to me. While I know it's not the primary purpose, a multidispatch library built on top of it could potentially do wonders for cleaning up some of the ugliness in the URL parsing libraries (which have quite a few of those "all str, or all bytes, but not a mixture" style interfaces). Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia