Re: srfi-0 and srfi-7

>>>>> "Neil" == Neil W Van Dyke <[email protected]> writes:

Neil> Thanks for the response.

Neil> 3. Are SRFI-0/7 feature names for MzScheme-specific extensions defined?
Neil>    I don't see any in "features.ss".
>> 
>> No, and for good reason.

Neil> I can only guess at the guiding philosophy; could you elaborate?

SRFI 7 is for writing portable programs based on specifications shared
by multiple implementations.  Adding "MzScheme-specific" extensions
defeats that goal, and SRFI 7 just isn't good at handling this case.

Neil> Also, there are cases like Scsh and Scheme48 declining to provide an
Neil> R5RS-compliant "integer->char".  So I need a way of talking about
Neil> how to get "ascii->char" behavior.

Ah ... what?  R5RS doesn't specify ASCII, and thus Scheme 48 and scsh
actually invite you not to write unportable programs by relying on
this  If you want something like ASCII->CHAR, it seems the way to go
about it is to provide a specification (in form of a SRFI, of course
:-) ) which you can then use.

Neil> And sometimes I just want to know which implementation I'm running on,
Neil> since I have a priori information about particular ways to do things on
Neil> that implementation for big wins or to work at all.  In fact, this is
Neil> probably what I need most often: "If we're using Foo Scheme, then do
Neil> THIS.  If Bar Scheme, then THAT.  If neither of those, but the
Neil> implementation supports a Baz API, then do THOSE THINGS.  If all else
Neil> fails, use THESE criminally inefficient R5RS-based procedures."

That of, course, is not only unportable now, it's also likely to make
a program written and working now fail in the future.

I know this situation is frustrating---but the methods are (IMHO) not
likely to improve it.

Your best bet for writing programs portable between PLT Scheme and
Scheme 48 / scsh is to use their respective module systems, and factor
out APIs that will work across both.  (This is actually a pretty
effective approach, and Matthew and I are slowly working on making it
easier still.)

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


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