Fractional/negative fixity?

apfelmus at apfelmus at
Tue Nov 7 11:47:52 EST 2006

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
>> 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!


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