[r6rs-discuss] Lexical Syntax

[Michael Sperber]

Alan Watson <alan at alan-watson.org> writes:

> William D Clinger wrote:
>> It sounds as though the R6RS has created a need for some
>> kind of tool and/or language that would allow us to read
>> R5RS data reliably and then to write that data reliably
>> as R6RS-readable data.  
>
> Such a tool would be trivial to write in R5RS Scheme. It would still be 
> worth having, though.

It certainly would be trivial to write in R6RS Scheme.  I was able to
hack the R5RS reader and writer that come with Scheme 48 to run in
Ikarus in about 20 minutes.  The result is attached.  The following R6RS
top-level program then can perform a trivial conversion:

(import (rnrs base)
	(rnrs programs)
	(prefix (de deinprogramm r5rs-write) r5rs:)
	(prefix (de deinprogramm r5rs-read) r5rs:)
	(rnrs io simple))

(r5rs:write
 (call-with-input-file (cadr (command-line))
   (lambda (port)
     (r5rs:read port))))
(newline)

It's only a proof-of-concept, with no claims as to its correctness,
completeness, usefulness, or R6RS compliance.  To be sure, there's a few
shortcomings, notably the reliance on R6RS's `string->number' in the
reader, which doesn't support '#' anymore, but I'm sure the interested
reader can easily fix that problem.  (As well as fixing the 80,000+
other failing test cases a decent test suite can probably be made to
find.)

-- 
Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla
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