Henning Thielemann wrote:
On Tue, 7 Nov 2006, Simon Marlow wrote:
I'd support fractional and negative fixity. It's a simple change to make, but we also have to adopt
http://hackage.haskell.org/cgi-bin/haskell-prime/trac.cgi/wiki /FixityResolution
I've added the proposal to the end of that page. In fact, the page already mentioned that we could generalise fixity levels, but it didn't mention fractional or negative values being allowed.
Maybe that page could also mention earlier proposals and the solutions without precedence numbers. I prefer the non-numeric approach with rules like "(<) binds more tightly than (&&)", because it says what is intended and it allows to make things unrelated that are unrelated, e.g. infix operators from different libraries.
This is a much more heavyweight change, and its not a clear win. Yes I agree that in some ways it's strange to enforce a total order between unrelated things, but on the other hand it's very convenient, and easy to understand. Currently the default fixity is infixl 9. That is, if you don't declare a fixity, you automatically get a fixity that can be used relative to every other operator. This is quite useful - I bet if we made it mandatory to declare all the relative fixities then we'd need to add fixity declarations to lots of code. I forsee this being quite tiresome. If you'd like to make a concrete proposal, then feel free to do so and I'll make sure it gets onto the wiki. Cheers, Simon