Fractional/negative fixity?

[apfelmus at quantentunnel.de]

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. 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