Brian Denheyer <firstname.lastname@example.org> wrote:
| Is there a way to "fake" dynamic-wind in a scheme which does not
| support it. It's not obvious to me that it can be done without
| low-level support of some sort.
The minutes of the legendary "June 1992" meeting at Xerox PARC
june-92-meeting.ps.gz> included a "user-mode" reference implementation
of dynamic-wind, but noted:
Since dynamic-wind interacts with call-with-current-continuation,
this implementation must replace the usual definition of the latter.
That is, *all* calls to call/cc must be to the one defined in the
dynamic-wind code (which saves away the original function value and
replaces it with its own, by set!-ing the global variable). This can
only work if no built-in route uses call/cc, and if the dynamic-wind
code appears lexical *before* any code that uses call/cc.
| Of course, if you could do it without low level support, then what's
| the point of it being in R5RS, right ?
Rob Warnock, 31-2-510 email@example.com
Network Engineering http://reality.sgi.com/rpw3/
Silicon Graphics, Inc. Phone: 650-933-1673
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