[Larceny-users] Bug in syntax-rules expander (R6RS semantics changed?)

[Felix Klock]

On Sep 25, 2009, at 9:04 AM, David Rush wrote:

> 2009/9/25 William D Clinger <will at ccs.neu.edu>:
>
>> it's a bug if Larceny doesn't support that semantics in
>> ERR5RS/R6RS modes.
>
> I haven't tried and don't much care, but it is good to know about
> LET-SYNTAX in this context. Having never used it before (and
> programmed around that in various ways) I didn't have any feel for
> what to expect. In point of fact, I can see it making sense for
> let-syntax working either way, depending on the emphasis on pragmatics
> versus semantic clarity.

One can always get the effect specified by R5RS by wrapping a (let  
() ...) around the (let-syntax ...), which could itself be specified  
as a separate syntax-rules macro.

I do not think the other direction is possible, which is the best  
argument I can see for making the change to the let-syntax scoping  
semantics.

(When Will suggests making an R5RS library providing the alternative  
let-syntax semantics, I assume he is thinking of using an explicitly- 
renaming procedural macro to accomplish that task.  But maybe I have  
made an invalid inference.)

-Felix