John Cowan <cowan_at_ccil.org> writes:
> Michael Sperber scripsit:
>
>> That's a pretty incomplete characterization of the discussion: Since
>> the semantics includes mutation, an eventual (bad) interaction with
>> threads is inevitable.
>
> Mutation and threads *never* interact well, but Scheme is full of
> mutation: if it didn't have mutation, it would be Erlang or something.
> Consequently, whoever is going to implement threads in Scheme must
> make many decisions about the behavior of threads, and the decision
> about parameters is just another of them.
Sure. All I'm arguing for is not making the wrong decision. The
interaction that SRFI 39 entails happens to be particularly hideous,
and unnecessary at that.
> # I agree that the API of parameters is not abstract, and that this
> # could be improved with separate procedures (or syntax) for creation,
> # mutation, reading and binding of dynamic variables. I did not propose
> # this because of the convergence by many implementations to the
> # "parameters" API and I wanted to place minimal burden on
> # implementors/users of this API.
So most everybody isn't happy with the API in SRFI 39. SRFIs are
perfectly suited for codifying widely implemented interfaces. It's
not a good idea to set something we know is defective into the
standard.
>> > 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.
Actually, thinking about it, with the R5.92RS interface the current
ports, implementing all of SRFI 39 on top of it is no longer a
problem. (Given that there's now `call-with-ports'.) So I think
there's even less reason to put SRFI 39 into the standard.
--
Cheers =8-} Mike
Friede, V?lkerverst?ndigung und ?berhaupt blabla
Received on Sat Feb 10 2007 - 05:24:28 UTC