- Gambit-list - mailman.iro.umontreal.ca

Commercial Users of Functional Programming: program is published, registration is open
by Matthew Flatt 21 Aoû '07

21 Aoû '07

[posted on behalf of the organizers] Friends, The program for the 2007 Commercial Users of Functional Programming workshop is now published. http://cufp.galois.com/ The workshop is co-located with ICFP, and will be held in Freiburg, Germany, on 4 October 2007. We had a terrific response to our call for talks, and there are twelve (!) speakers describing commercial applications, variously written in Caml Erlang F# Haskell ML Scheme The talks are informal, and there are no proceedings. We'll just have fun learning about functional programming used to solve real problems. Do come! Kathleen Fisher Simon Peyton Jones

1 0

Re: [gambit-list] floating point number representation
by Marc Feeley 21 Aoû '07

21 Aoû '07

On 20-Aug-07, at 5:11 PM, naruto canada wrote: > On 8/21/07, naruto canada <narutocanada(a)gmail.com> wrote: >> On 8/21/07, Marc Feeley <feeley(a)iro.umontreal.ca> wrote: >>> >>> On 20-Aug-07, at 3:41 PM, naruto canada wrote: >>> >>>> hi >>>> >>>> (+ 1.0 3.0) >>>> ;; 4. >>>> >>>> can I have "4.0" instead? >>>> where do I have to change in "lib/_num.scm"? (I am guessing) >>> >>> In lib/_num.scm change >>> >>> (##define-macro (macro-chez-fp-syntax) #f) >>> >>> to >>> >>> (##define-macro (macro-chez-fp-syntax) #t) >>> >>> and do a "make". >> >> I've just tried it, it segfaults. >> (+ 4.0 5.0) >> Segmentation fault > > Gambit Version 4.0 beta 22 >> (+ 4.0 5.0) > Segmentation fault Strange... it works fine when I make the change: > (+ 4.0 5.0) 9.0 Marc

2 2

Re: [gambit-list] (eval (cons func '(1 2))) don't work
by Marc Feeley 21 Aoû '07

21 Aoû '07

On 20-Aug-07, at 5:34 PM, naruto canada wrote: >> >> I'm not sure what you tried but Gambit supports a multiple argument >> apply (the last argument is a list of the remaining arguments. So: >> >>> (apply + '(1 2 3 4)) >> 10 >>> (apply + 1 '(2 3 4)) >> 10 >>> (apply + 1 2 '(3 4)) >> 10 >>> (apply + 1 2 3 '(4)) >> 10 >>> (apply + 1 2 3 4 '()) >> 10 >> >> Marc >> >> > > You are right, I had a mismatch of arity. It works now. > Still, both methods should be equivalent. In general (apply E1 E2) != (eval (cons E1 E2)) because eval tries to recursively evaluate its argument. It will try to evaluate the **result** of evaluating E1, and all the elements of the list **resulting** from the evaluation of E2. With apply the second round of evaluation does not occur. Note that sometimes there is no difference because 5 = (eval 5) = (eval (eval 5)) = ... but in other cases there is a difference because car = (eval 'car) != (eval (eval 'car)) != ... Marc

2 1

Re: [gambit-list] (eval (cons func '(1 2))) don't work
by naruto canada 21 Aoû '07

21 Aoû '07

On 8/21/07, naruto canada <narutocanada(a)gmail.com> wrote: > On 8/21/07, Etienne Laurin <laurieti(a)iro.umontreal.ca> wrote: > > On Tue, Aug 21, 2007 at 02:08:43AM +0800, naruto canada wrote: > > > ;; propositional calculator > > > (map (lambda (p) (implies p p)) (list #t #f)) > > > (cross-product '((0 1) (0 1) (0 1) ) ) > > > (cross-product '((0 1) (0 1) (0 1) (0 1)) ) > > > (define (prop-calc func lst) > > > (map (lambda (x) (eval (cons func x))) lst) > > > ) > > > (prop-calc (lambda (p) (implies p p)) (bag-of (list (amb-list (list #t > > > #f))))) ;; test tautology > > > 'done (exit) > > > > You can use apply instead: > > > > (map (lambda (x) (apply func x)) lst) > > > > Unless you really need to evaluate arbitrary scheme expressions, > > eval doesn't need to be used and shouldn't have to be. > oops, forgot to reply to list. apply won't work more then one parameters (I've tried it): (prop-calc (lambda (p q) (iff (implies p q) (implies (not q) (not p)))) (cross-product '((#t #f)(#t #f))) ) Besides, when I start on predicate calculus, it's going to become ugly (symbolic), I need to make sure I can still evaluate arbitrary lambdas before planning out data structure. > > > > > Etienne Laurin > > >

2 1

floating point number representation
by naruto canada 21 Aoû '07

21 Aoû '07

hi (+ 1.0 3.0) ;; 4. can I have "4.0" instead? where do I have to change in "lib/_num.scm"? (I am guessing) Thanks

2 1

http://www.iro.umontreal.ca/~gambit/ only has 4.0b22
by naruto canada 21 Aoû '07

21 Aoû '07

http://www.iro.umontreal.ca/~gambit/ only has 4.0b22, where can I obtain 4.0b23? Thanks.

1 0

(eval (cons func '(1 2))) don't work
by naruto canada 21 Aoû '07

21 Aoû '07

hi how to make this code work with gambit-c? (define (func x y) (+ x y)) (eval (cons func '(1 2))) Thanks.

2 1

Re: [gambit-list] (eval (cons func '(1 2))) don't work
by andrew cooke 20 Aoû '07

20 Aoû '07

[replying to list this time - realised my last example below is probably what you intended] it think it does work - the error seems reasonable to me. what are you trying to do? > (define (func x y) (+ x y)) > (eval (func 1 2)) 3 1> (eval '(func 1 2)) 3 > (eval `(func ,@'(1 2))) 3 1> (eval '(cons 4 (func 1 2))) (4 . 3) 1> (eval (cons 'func '(1 2))) 3 (eval (func 1 2)) is (eval 3) which is 3 (eval '(func 1 2)) evaluates the quoted expression (eval `(func ,@'(1 2))) is (eval '(func 1 2)) (eval (cons 'func '(1 2))) is (eval (func 1 2)) andrew

1 0

Hygienic macros failing?
by andrew cooke 20 Aoû '07

20 Aoû '07

I may be misunderstanding hygienic macros here, but as far as I can tell I am getting variable capture. (define-syntax bad (syntax-rules () ((_ (arg1 ...) (arg2 ...)) (receive (a b c) (values arg1 ...) (newline) (write (list arg2 ...)))))) (receive (a b c) (values 1 2 3) (bad (7 8 9) (a b c))) This displays (7 8 9) when arg2 should be (1 2 3) (the value of a b c in the calling code, not the value in "bad"). It can be avoided by using different variable names, but that should not be necessary, right? Thanks, Andrew PS Gambit Version 4.0 beta 22, on Suse linux 10.2, amd64.

5 6

Segfault while running Gambit; values/receive efficiency
by andrew cooke 20 Aoû '07

20 Aoû '07

Hi, Well, first of all this segfaults: qp6 napito: ./napito-base.scm Segmentation fault which I guess is a bug. But also, I got a bit carried away trying to remove function calls in matrix multiplication. I'd appreciate some advice - if the code worked, would it be efficient? In particular, do the values/receive pairs get "compiled away"? I hope the code is fairly obvious - I'm trying to unpack a list with contains the non-zero elements from a typical 2D geometric transform and then do the matrix multiplication on a point. Thanks, Andrew

2 5