The simple answer is, go look at @partial's __call__: https://github.com/markshroyer/pointfree/blob/master/pointfr...

All that code is executing on every partial call. So, a very brief list of reasons not to use this in production:

1. overhead

2. complexity

3. debugging

4. don't fight the language

edited to add: I just want to emphasize that I think it's a really, really neat hack!

Because it deviates entirely from Python's semantics.

edit: In other words, "Don't fight the language" as another commenter said.