[r6rs-discuss] [Formal] SRFI-39 should be made an R6RS library
sperber at informatik.uni-tuebingen.de
Fri Feb 9 02:05:02 EST 2007
John Cowan <cowan at ccil.org> writes:
> I have searched the various status reports and seen nothing about
> dynamic binding, dynamic variables, or parameters. I suggest
> that SRFI-39 be incorporated into R6RS as the (r6rs parameters)
> Judging by the SRFI-39 mail archives, the only thing controversial
> about the final form of the SRFI is the behavior when interacting
> with threads. As threads are not part of R6RS, the issue does not
That's a pretty incomplete characterization of the discussion: Since
the semantics includes mutation, an eventual (bad) interaction with
threads is inevitable. For gory details, check out:
Martin Gasbichler, Eric Knauel, Michael Sperber Richard A. Kelsey: How
to Add Threads to a Sequential Language Without Getting Tangled Up, In
The 2003 Scheme Workshop, Boston, Ma., October 2003.
This paper is available from:
Moreover, the interface for parameters is bizarre. Some elaboration
on that argument can be found at:
In any case, SRFI 39 (standing by itself) can be implemented portably
on top of R5.92RS. It may indeed be a good idea to have a standard
policy and/or interface for dynamically bound parameters, but there
doesn't seem to be universal agreement on what that should look like.
> The reason for making parameters part of the standard, beside their
> general utility, is that they are intertwingled with the current-*-port
> facilities, which are explicitly specified as parameters by SRFI-39.
> As a result, it is hard to load a portable implementation of parameters
> into a Scheme that doesn't have it; current-*-port cannot be rebound
> by parameterize correctly.
That seems to be a defect of SRFI 39, and hardly sufficient reason to
force it into the standard.
Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla
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