[R6RS] Making -> a valid identifier

Anton van Straaten anton at appsolutions.com
Wed May 24 12:02:08 EDT 2006

Will wrote:
> Kent wrote:
>>The simplest approach to adding symbols that start with -> would be the
>>one you suggested a long time ago:
>>  <peculiar identifier> -> + | - | ... | -> <subsequent>*
>>This is "piling feature on top of feature", but anything else short of an
>>"excluding <number>" solution will likely further complicate the identifier
>>grammar and still feel like piling feature on top of feature.
> I agree with the productions shown above.

I also agree.  I don't consider the feature-piling argument to have 
sufficient jurisdiction here.  The syntax is going to have weird quirks 
like this if it is to support the weird quirkiness of humans who want to 
start words with "->".  It's much better to have explicit rules for such 
things than having to detect them via a process of elimination.

>>If we do figure out how to add identifiers that start with -> to the
>>language, should we rename exact->inexact to ->inexact and inexact->exact
>>to ->exact?  It's always seemed funny that exact->inexact allows inexact
>>inputs and inexact->exact allows exact inputs.
> That would be fine with me, except I'd want to retain the
> exact->inexact and inexact->exact names for backward
> compatibility.  They could be banished to the R5RS
> compatibility library.

This is fine with me too.  I've added exact->inexact and inexact->exact 
to an r5rs-compatibility library in the core/library split proposal, in SVN.


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