[m-dev.] Re: [m-rev.] field syntax (was: smart recompilation)

[Fergus Henderson]

On 06-Jul-2001, Ralph Becket <rbeck at microsoft.com> wrote:
> > From: Fergus Henderson [mailto:fjh at cs.mu.OZ.AU]
> > Sent: 06 July 2001 12:09
> > 
> > `|' would be nice, but unfortunately that's taken.
> > Anyway, there's a shortage of single-character operators, and I don't
> > think this is important enough for that, so I'd recommend a two- or
> > three-character operator name.
> 
> That's a moot point...  I'd be inclined to go for '$'.

I think that would be confusing, at least for Haskell programmers,
since Haskell uses $ for function composition.  It would be making
things unnecessarily difficult to define that as *reverse* function
composition.

And I also have the same objection as for `|', i.e. I don't think
this operator is important enough to steal one of the last remaining
single-character operators.

> > '$|', which I have seen used in Haskell code, would also be OK,
> 
> Ugh.

I think that's quite nice, since it is reminiscent of both Haskell's
function composition operator and the Unix pipe operator.

> > but unfortunately that lexes as two tokens, not one.
> > The only characters which can be combined to form operators without
> > changing the lexical syntax are the following:
> > 
> > 	# $ & + - . / : < = > ? @ ^ ~ \
> > 
> > But I guess "$>" would work.
> 
> Could we reuse '-->'?

We could, but I wouldn't recommend it -- I think that would be confusing.
Also it probably doesn't have the right precedence.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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