Mark partial functions as such

[Richard Eisenberg]

Proposal: Mark partial functions in `base` as partial

Motivation: I'm about to teach Haskell to a classful of beginners. In my experience, they will soon reach for functions like `head` and `tail`, because pattern-matching is foreign to them. I would love just to be able to say "Don't use partial functions", but many students will not easily be able to tell partial functions from total ones.

I do expect this problem to work itself out rather quickly, and then students will be able to identify partial functions, but loudly marking partial functions as partial seems like a small service to everyone and a bigger one to newbies. I don't see any downsides.

Thoughts?

Thanks,
Richard