* stupid mail about letrec
@ 2002-03-21 17:22 Sebastien.deMentendeHorne
2002-03-21 23:09 ` Neil Jerram
0 siblings, 1 reply; 7+ messages in thread
From: Sebastien.deMentendeHorne @ 2002-03-21 17:22 UTC (permalink / raw)
sorry...
have confused letrec and let* (in fact, csi (chicken interpreter) and scheme
(MIT-scheme interpreter, i guess)) gave me the solution I was expecting with
letrec).
Is letrec supposed to have at least the same effect of let* ?
Sébastien de Menten | ELECTRABEL
Tel: ++32 10 48 51 76 | Quantitative Analysis,
Fax: ++32 10 48 51 09 | Place de l'université, 16, 4ème étage
Gsm: ++32 478 789 444 | B-1348 Louvain-la-Neuve, BELGIUM
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* Re: stupid mail about letrec
2002-03-21 17:22 stupid mail about letrec Sebastien.deMentendeHorne
@ 2002-03-21 23:09 ` Neil Jerram
0 siblings, 0 replies; 7+ messages in thread
From: Neil Jerram @ 2002-03-21 23:09 UTC (permalink / raw)
Cc: guile-user
>>>>> "Sebastien" == Sebastien deMentendeHorne <Sebastien.deMentendeHorne@electrabel.com> writes:
Sebastien> sorry... have confused letrec and let* (in fact, csi
Sebastien> (chicken interpreter) and scheme (MIT-scheme
Sebastien> interpreter, i guess)) gave me the solution I was
Sebastien> expecting with letrec).
So chicken and MIT-scheme don't give you an error for the letrec
expression that you quoted before?
Sebastien> Is letrec supposed to have at least the same effect of
Sebastien> let* ?
No. letrec is more similar (in my way of seeing things) to let than
to let*. See R5RS for the details.
Neil
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* stupid mail about letrec
@ 2002-03-25 13:02 Sven Hartrumpf
2002-03-25 16:02 ` Thomas Bushnell, BSG
0 siblings, 1 reply; 7+ messages in thread
From: Sven Hartrumpf @ 2002-03-25 13:02 UTC (permalink / raw)
>So chicken and MIT-scheme don't give you an error for the letrec
>expression that you quoted before?
No, all return 8 for (letrec ((a 2) (b (* a 4))) b).
Also mzscheme, bigloo, chez, sisc, scsh, gauche, gambit.
Only SCM behaves like guile.
This might make an interesting posting in comp.lang.scheme :-)
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* Re: stupid mail about letrec
2002-03-25 13:02 Sven Hartrumpf
@ 2002-03-25 16:02 ` Thomas Bushnell, BSG
2002-03-25 18:33 ` Per Bothner
2002-03-25 18:50 ` Marius Vollmer
0 siblings, 2 replies; 7+ messages in thread
From: Thomas Bushnell, BSG @ 2002-03-25 16:02 UTC (permalink / raw)
Cc: guile-user
Sven Hartrumpf <Sven.Hartrumpf@FernUni-Hagen.de> writes:
> >So chicken and MIT-scheme don't give you an error for the letrec
> >expression that you quoted before?
>
> No, all return 8 for (letrec ((a 2) (b (* a 4))) b).
> Also mzscheme, bigloo, chez, sisc, scsh, gauche, gambit.
> Only SCM behaves like guile.
> This might make an interesting posting in comp.lang.scheme :-)
Yes, but it is an error nontheless.
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* Re: stupid mail about letrec
2002-03-25 16:02 ` Thomas Bushnell, BSG
@ 2002-03-25 18:33 ` Per Bothner
2002-03-25 18:50 ` Marius Vollmer
1 sibling, 0 replies; 7+ messages in thread
From: Per Bothner @ 2002-03-25 18:33 UTC (permalink / raw)
Cc: Sven Hartrumpf, guile-user
Thomas Bushnell, BSG wrote:
> Sven Hartrumpf <Sven.Hartrumpf@FernUni-Hagen.de> writes:
>
>>>So chicken and MIT-scheme don't give you an error for the letrec
>>>expression that you quoted before?
>>
>>No, all return 8 for (letrec ((a 2) (b (* a 4))) b).
>>Also mzscheme, bigloo, chez, sisc, scsh, gauche, gambit.
>>Only SCM behaves like guile.
>>This might make an interesting posting in comp.lang.scheme :-)
>
>
> Yes, but it is an error nontheless.
But an error that implementations are not requied to detect.
And it is not unreasonable to consider this an implementation
extension.
--
--Per Bothner
per@bothner.com http://www.bothner.com/per/
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* Re: stupid mail about letrec
2002-03-25 16:02 ` Thomas Bushnell, BSG
2002-03-25 18:33 ` Per Bothner
@ 2002-03-25 18:50 ` Marius Vollmer
2002-03-25 19:48 ` Neil Jerram
1 sibling, 1 reply; 7+ messages in thread
From: Marius Vollmer @ 2002-03-25 18:50 UTC (permalink / raw)
Cc: Sven Hartrumpf, guile-user
tb@becket.net (Thomas Bushnell, BSG) writes:
> Sven Hartrumpf <Sven.Hartrumpf@FernUni-Hagen.de> writes:
>
> > >So chicken and MIT-scheme don't give you an error for the letrec
> > >expression that you quoted before?
> >
> > No, all return 8 for (letrec ((a 2) (b (* a 4))) b).
> > Also mzscheme, bigloo, chez, sisc, scsh, gauche, gambit.
> > Only SCM behaves like guile.
> > This might make an interesting posting in comp.lang.scheme :-)
>
> Yes, but it is an error nontheless.
However, I think it is an interesting extension. Internal defines
would behave more 'natural' that way. It's probably better to define
a new letrec* form, tho, instead of changing the definition of letrec.
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* Re: stupid mail about letrec
2002-03-25 18:50 ` Marius Vollmer
@ 2002-03-25 19:48 ` Neil Jerram
0 siblings, 0 replies; 7+ messages in thread
From: Neil Jerram @ 2002-03-25 19:48 UTC (permalink / raw)
Cc: Thomas Bushnell, BSG, Sven Hartrumpf, guile-user
>>>>> "Marius" == Marius Vollmer <mvo@zagadka.ping.de> writes:
Marius> tb@becket.net (Thomas Bushnell, BSG) writes:
>> Sven Hartrumpf <Sven.Hartrumpf@FernUni-Hagen.de> writes:
>>
>> > >So chicken and MIT-scheme don't give you an error for the letrec
>> > >expression that you quoted before?
>> >
>> > No, all return 8 for (letrec ((a 2) (b (* a 4))) b).
>> > Also mzscheme, bigloo, chez, sisc, scsh, gauche, gambit.
>> > Only SCM behaves like guile.
>> > This might make an interesting posting in comp.lang.scheme :-)
>>
>> Yes, but it is an error nontheless.
Marius> However, I think it is an interesting extension. Internal defines
Marius> would behave more 'natural' that way. It's probably better to define
Marius> a new letrec* form, tho, instead of changing the definition of letrec.
I'm pretty sure there was a big discussion about this a few years ago.
Neil
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2002-03-21 17:22 stupid mail about letrec Sebastien.deMentendeHorne
2002-03-21 23:09 ` Neil Jerram
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2002-03-25 13:02 Sven Hartrumpf
2002-03-25 16:02 ` Thomas Bushnell, BSG
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2002-03-25 18:50 ` Marius Vollmer
2002-03-25 19:48 ` Neil Jerram
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