[r6rs-discuss] R6 counterproposal
lord at emf.net
Mon May 28 16:07:27 EDT 2007
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
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
> 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
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