On 05/12/11 15:32, Andy Wingo wrote: > On Thu 12 May 2011 14:36, Jim Rees <[email protected]> writes: > >> On Thu, May 12, 2011 at 7:36 AM, Alaric Snell-Pym <[email protected]> >> wrote: >> >> But what happens if you try to REVERSE a syntax-object wrapping a list? >> You can't - >> >> Overall your essay is illuminating, but reversing a syntax-object >> representing a list is easy in an R6RS-conforming implementation. >> >> (define (reverse-wrapped-list obj) >> (syntax-case obj () >> ((e ...) (reverse #'(e ...))))) > > This works on psyntax systems, where lists are never wrapped, but AFAIK > it does not work on Racket, where lists are wrapped.
Yeah, I based my point on a statement by Eli that, IIRC, stated that even the lists get magic wrapped cons cells some of the time. > Andy ABS -- Alaric Snell-Pym http://www.snell-pym.org.uk/alaric/ _______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
