[Ur] Functional infix operators ?

[Ziv Scully]

Both these function combinators and more concise operators for sources
would be encompassed by user-defined infix operators. I expect this would
be more work than the proposed patch, but if the demand for infix operators
is high enough, I think this would be better than an ever-expanding
unconfigurable hodgepodge of built-in operators.

On Thu, Feb 19, 2015 at 9:46 PM, Timothy Beyer <beyert at fastmail.net> wrote:

> At Thu, 19 Feb 2015 18:34:49 +0000 (UTC),
> Gabriel Riba wrote:
> >
> > Adam Chlipala <adamc <at> csail.mit.edu> writes:
> >
> > >
> > > OK, I see.  By "functional," you meant "related to function
> application,
> > > composition, etc.", not a general mechanism for introducing new infix
> > > operators.
> > >
> > > If you (or anyone else) want to experiment with tweaking src/urweb.grm
> > > to add some new operators, I'll be happy to accept a patch embodying
> > > tasteful choices. :)  (May also require adding to lib/ur/top.ur[s] new
> > > definitions of conventionally named functions, to which the new
> > > operators desugar.)
> > >
> >
> > Hello!
> >
> > I've worked out a solution for the function application and composition
> > operators, after revising the mlton manuals for ml-lex and ml-yacc, and
> it
> > works.
> >
> > I need your opinion to ensure if it is complete.
> >
> > The operators in this trial are
> >
> > (<|) : forward application (right associative), named FWDAPP in .lex and
> .grm
> > (|>) : reverse application (left associative), named REVAPP
> > (<<<) : right-to-left composition (right associative) (equivalent to ML's
> > (o)), named COMPOSE
> > (>>>) : left-to-right composition (right associative), named ANDTHEN
>
> I can't speak for Adam, but I've wanted infix apply and compose operators
> in Ur/Web for a while, so I'm looking forward to trying this patch.
>
> If Ur/Web ever gains pattern matching on a function level (eg. without
> requiring an extra case statement), plus pattern matching extensions such
> as OR patterns, and more concise operators for sources, then it would be
> absolute bliss for me, even though what I suggest is quite a lot of
> syntactic sugar.
>
> Regards,
> Tim
>
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