[r6rs-discuss] R6 counterproposal

From: Thomas Lord <lord>
Date: Mon, 28 May 2007 13:07:27 -0700

Joe Marshall wrote:
> I'm confused. On comp.lang.scheme you proposed introducing FEXPRs
> into the language, but you describe them as a call-by-name mechanism.
>
> Traditionally, a FEXPR is a first-class macro. When applied, the
> source code of the arguments is passed in.
>
> A call-by-name procedure, on the other hand, would take its arguments
> as thunks (like Algol 60!). Call-by-need is a variation where the
> value is memoized if it is ever forced (like Haskell does).
>
> So which is it that you are proposing?

I confused matters by formulating fexprs two different (dual of one another)
ways and also by not clearly distinguishing between Scheme identifiers
and meta-syntactic variables in a formula. Nevermind:

It's sufficient to think of classic lisp-style fexprs and first-class
environments.
Any other description is just some dual of that in which those two things
can be expressed and those two things are enough to express all other
descriptions.

-t



>
> On 5/28/07, Joe Marshall <jmarshall at alum.mit.edu> wrote:
>> So am I right in assuming that you were thinking of FEXPRs in the
>> general case rather than the way SCM uses the term?
>>
>> On 5/27/07, Thomas Lord <lord at emf.net> wrote:
>> > Thomas Lord wrote:
>> > > In the *general case* you can't expand fexpr-style macros at
>> > > run-time however
>> >
>> > ur... that's "until" run-time, not "at," of course.
>> >
>> > -t
>> >
>> >
>>
>>
>> --
>> ~jrm
>>
>
>
Received on Mon May 28 2007 - 16:07:27 UTC