* [Caml-list] eval order and 'and'
@ 2002-09-11 1:21 Chris Hecker
2002-09-11 7:30 ` malc
0 siblings, 1 reply; 6+ messages in thread
From: Chris Hecker @ 2002-09-11 1:21 UTC (permalink / raw)
To: caml-list
Does "let a and b in" guarantee a is evaluated before b, like "let a in let
b in" does?
Chris
PS. I don't think this is a FAQ, but it's basically impossible to
construct a search that finds this specific question, so who knows! ;)
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Caml-list] eval order and 'and'
2002-09-11 1:21 [Caml-list] eval order and 'and' Chris Hecker
@ 2002-09-11 7:30 ` malc
0 siblings, 0 replies; 6+ messages in thread
From: malc @ 2002-09-11 7:30 UTC (permalink / raw)
To: Chris Hecker; +Cc: caml-list
On Tue, 10 Sep 2002, Chris Hecker wrote:
> Does "let a and b in" guarantee a is evaluated before b, like "let a in let
> b in" does?
>
> Chris
>
> PS. I don't think this is a FAQ, but it's basically impossible to
> construct a search that finds this specific question, so who knows! ;)
<quote>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Caml-list] eval order and 'and'
2002-09-11 7:47 ` Sven LUTHER
@ 2002-09-11 8:32 ` Hendrik Tews
0 siblings, 0 replies; 6+ messages in thread
From: Hendrik Tews @ 2002-09-11 8:32 UTC (permalink / raw)
To: caml-list
Sven LUTHER writes:
Date: Wed, 11 Sep 2002 09:47:53 +0200
Subject: Re: [Caml-list] eval order and 'and'
So he can do things like :
if x <> 0 and 1 / x ...
like it is possible to do in C, instead of doing :
if x <> 0 then if 1 / x ...
which gives more lines of code, and needs to redefine two time the else
condition.
Anyway, i don't think the order is defined, but in any case, i guess
it would be revere sequential if anything (execution starts from the
right).
IMO you are mixing things up, "and" is not an operator and
if x <> 0 and 1 / x ...
is not legal ocaml.
For let a = ex1 and b = ex2 ... the manual says that the
evaluation is unspecified (6.7.1. local definitions).
For the logical operators (&&, &, ||, or) the manual specifies left
to right (non-strict) evaluation (Module Pervasives).
Bye,
Hendrik
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Caml-list] eval order and 'and'
2002-09-11 5:05 Arturo Borquez
2002-09-11 7:19 ` Chris Hecker
@ 2002-09-11 7:47 ` Sven LUTHER
2002-09-11 8:32 ` Hendrik Tews
1 sibling, 1 reply; 6+ messages in thread
From: Sven LUTHER @ 2002-09-11 7:47 UTC (permalink / raw)
To: Arturo Borquez; +Cc: Chris Hecker, caml-list
On Wed, Sep 11, 2002 at 01:05:46AM -0400, Arturo Borquez wrote:
> Chris Hecker <checker@d6.com> wrote:
>
> >
> >Does "let a and b in" guarantee a is evaluated before b, like "let a in let
> >b in" does?
> >
> Sorry but I don't understand the purpose of your question.
> If a and b are functions with 'related side effects' the secure
> way should be the later ('let a in let b ..'), otherwise
> the order of evaluation in the first case is irrelevant
> as a and b are two unrelated functions (with no side effects),
> or 'let a and b in ..' is the same as 'let b and a in ..'
So he can do things like :
if x <> 0 and 1 / x ...
like it is possible to do in C, instead of doing :
if x <> 0 then if 1 / x ...
which gives more lines of code, and needs to redefine two time the else
condition.
Anyway, i don't think the order is defined, but in any case, i guess
it would be revere sequential if anything (execution starts from the
right).
But then again, it could be different in bytecode and in native code.
Friendly,
Sven Luther
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^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [Caml-list] eval order and 'and'
2002-09-11 5:05 Arturo Borquez
@ 2002-09-11 7:19 ` Chris Hecker
2002-09-11 7:47 ` Sven LUTHER
1 sibling, 0 replies; 6+ messages in thread
From: Chris Hecker @ 2002-09-11 7:19 UTC (permalink / raw)
To: Arturo Borquez; +Cc: caml-list
> >Does "let a and b in" guarantee a is evaluated before b, like "let a in let
> >b in" does?
>Sorry but I don't understand the purpose of your question.
I was simply asking if the 'and' construct guarantees order or not (is a
"sequence point" in C terminology), that's all.
Chris
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^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [Caml-list] eval order and 'and'
@ 2002-09-11 5:05 Arturo Borquez
2002-09-11 7:19 ` Chris Hecker
2002-09-11 7:47 ` Sven LUTHER
0 siblings, 2 replies; 6+ messages in thread
From: Arturo Borquez @ 2002-09-11 5:05 UTC (permalink / raw)
To: Chris Hecker; +Cc: caml-list
Chris Hecker <checker@d6.com> wrote:
>
>Does "let a and b in" guarantee a is evaluated before b, like "let a in let
>b in" does?
>
Sorry but I don't understand the purpose of your question.
If a and b are functions with 'related side effects' the secure
way should be the later ('let a in let b ..'), otherwise
the order of evaluation in the first case is irrelevant
as a and b are two unrelated functions (with no side effects),
or 'let a and b in ..' is the same as 'let b and a in ..'
Regards.
--
Arturo Borquez
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2002-09-11 1:21 [Caml-list] eval order and 'and' Chris Hecker
2002-09-11 7:30 ` malc
2002-09-11 5:05 Arturo Borquez
2002-09-11 7:19 ` Chris Hecker
2002-09-11 7:47 ` Sven LUTHER
2002-09-11 8:32 ` Hendrik Tews
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