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/FixityResolut...
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. Consequently a precedence relation to general infix operators like ($) and (.) had be defined in each library.
I think that computable real fixity levels are useful, too. A further step to complex numbers is not advised because those cannot be ordered. But to be serious, the non-numeric rule based approach yields lattice-valued fixity levels. If we use a CPO, we gain ultimate expressiveness by being able to express fixity levels as fixed points of continuous functionals! Regards, apfelmus