Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Joshua D. Guttman]

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From: guttman@mitre.org (Joshua D. Guttman)
To: Daniel de Rauglaudre <daniel.de_rauglaudre@inria.fr>
Cc: guttman@mitre.org (Joshua D. Guttman)
Subject: Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]
Date: 16 May 2002 19:21:12 -0400
Message-ID: <nhak7q38ys7.fsf@banjara.mitre.org>

Daniel de Rauglaudre <daniel.de_rauglaudre@inria.fr> writes:

>   > Really?  Why did someone decide that inclusion was a bad idea?
>   
>   I say it. Camlp4 and the attempts to improve the syntax have been
>   considered *officially* by the OCaml team as a "not serious" work and a
>   "loss of time".

I'm sorry to hear this.  It's regrettable.  Camlp4 seems so useful to
me.

        Joshua 


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[Caml-list] Generating C stubs

[Jérôme Marant]

  Hi,

    In order to avoid spending some time on writing C stubs
    myself, I'd like them to be generated automaticaly.
    There are currently 3 stub generators: camouflage, ffi
    and another one I don't recall (IIRC, someone claimed
    that he was working on a SWIG interface).

    I'm a bit confused since I don't really know what generator
    to choose among all those. Moreover, they all seem to have
    been last update in august 2001 and the C interface may
    have changed since.

    Has anyone experiences and advices about this?

    Thanks in advance. 

    Regards,

-- 
Jérôme Marant
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Re: [Caml-list] Generating C stubs

[Jocelyn Sérot]

Le mercredi 15 mai 2002, à 11:13 , Jérôme Marant a écrit :

>   Hi,
>
>     In order to avoid spending some time on writing C stubs
>     myself, I'd like them to be generated automaticaly.
>     There are currently 3 stub generators: camouflage, ffi
>     and another one I don't recall (IIRC, someone claimed
>     that he was working on a SWIG interface).
>
>     I'm a bit confused since I don't really know what generator
>     to choose among all those. Moreover, they all seem to have
>     been last update in august 2001 and the C interface may
>     have changed since.
>
>     Has anyone experiences and advices about this?
>
>     Thanks in advance.
>
>     Regards,
>


I've been using CAMLIDL (http://caml.inria.fr/camlidl/) extensively and 
it works well.
It does not work directly from your C headers (.h) but from a IDL 
signature, but writting this
sig is straightforward in most of the cases.

Jocelyn

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Re: [Caml-list] Generating C stubs

[Jérôme Marant]

On Wed, May 15, 2002 at 11:49:50AM +0200, Jocelyn Sérot wrote:
> 
> I've been using CAMLIDL (http://caml.inria.fr/camlidl/) extensively and 
> it works well.
> It does not work directly from your C headers (.h) but from a IDL 
> signature, but writting this
> sig is straightforward in most of the cases.

  I thought that CamlIDL was targeted at COM and interprocess communication,
  wasn't it?

-- 
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Re: [Caml-list] Generating C stubs

[Florian Hars]

Jérôme Marant wrote:
>   I thought that CamlIDL was targeted at COM and interprocess communication,
>   wasn't it?

Yeah, the CamlIDL web site is one of the worst marketing blunders in the
history of modern computing in insinuating that it is exclusively targeted
at Windows-only programs. Unix only enters the picture as an afterthought
further down the page where everyone who is not looking for a Windows
solution has long since stopped reading. (Apart form the fact that no
sane programmer in full possession of his mental abilities would use
something with "IDL" in its name for a task as simple as linking to a
shared library :-))

Why not start the page with something like
"CamlIDL generates stub code to use C libraries and C++ classes
from Objective Caml from high level definitions. Under Windows it can
also provide COM bindings." 

And maybe the Ocaml manual should mention the existence of CamlIDL in
the introduction of the chapter about interfacing C with Ocaml, like
(stealing parts from the lower half of the website) "The following chapter
documents the low level interface between C and Objective Caml. For
practical programming tasks it might be more appropiate to use a tool
like CamlIDL that operates on a higher level of abstraction and takes
care of details such as those pesky Val_xxx and Xxx_val macros, proper
registration of GC roots, the different calling conventions from bytecode
and from native-code, etc."

Yours, Florian Hars.
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Re: [Caml-list] Generating C stubs

[Markus Mottl]

Florian Hars schrieb am Donnerstag, den 16. Mai 2002:
> And maybe the Ocaml manual should mention the existence of CamlIDL in
> the introduction of the chapter about interfacing C with Ocaml, like
> (stealing parts from the lower half of the website) "The following chapter
> documents the low level interface between C and Objective Caml.

And maybe it could also be made part of the distribution? We now already
have camlp4 and ocamldoc in it so a few bytes more don't make a big
difference anyway.

LG,
Markus

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Austrian Research Institute
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[Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Daniel de Rauglaudre]

On Thu, May 16, 2002 at 09:34:06AM +0200, Markus Mottl wrote:

> And maybe it could also be made part of the distribution? We now already
> have camlp4 and ocamldoc in it so a few bytes more don't make a big
> difference anyway.

The inclusion of Camlp4 being eventually a bad idea, in next version,
Camlp4 will be distributed separately, like before.

-- 
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daniel.de_rauglaudre@inria.fr
http://cristal.inria.fr/~ddr/
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Chris Hecker]

>The inclusion of Camlp4 being eventually a bad idea, in next version,
>Camlp4 will be distributed separately, like before.

Why?  It seemed like a great idea to me!

And what's going to happen with streams?

Chris

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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[John Prevost]

>>>>> "ddr" == Daniel de Rauglaudre <daniel.de_rauglaudre@inria.fr> writes:

    ddr> The inclusion of Camlp4 being eventually a bad idea, in next
    ddr> version, Camlp4 will be distributed separately, like before.

Really?  Why did someone decide that inclusion was a bad idea?

John.
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Daniel de Rauglaudre]

On Thu, May 16, 2002 at 03:39:45PM -0400, John Prevost wrote:

> Really?  Why did someone decide that inclusion was a bad idea?

I say it. Camlp4 and the attempts to improve the syntax have been
considered *officially* by the OCaml team as a "not serious" work and a
"loss of time". As I worried about that, and asked for more information,
it has been confirmed by the team, moreover with several personnal attacks.

Sorry for this "human" problem, but I cannot create and have
imagination in my work when I am considered like that.

Camlp4 continues and I made many changes, but in the previous CVS
distribution, directory "camlp4", no more "ocaml/camlp4". It will
be distributed normally just after OCaml releases and perhaps with
intermediate releases.

-- 
Daniel de RAUGLAUDRE
daniel.de_rauglaudre@inria.fr
http://cristal.inria.fr/~ddr/
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Chris Hecker]

I don't want to get into any "human problem" with the inria folks, but a 
brief technical note is warranted, I think:

I believe meta-programming, both at the parsing level that camlp4 does, and 
taking it farther to being able to meta-program with types, other 
semantics, at code gen time, and throughout the compiler, is a very 
important area of research for moving programming languages (and the craft 
of programming) forward.  There seems to be a lot of research on this 
(camlp4 has been referenced in research papers a couple times), and I hope 
there's more in the future.

I don't care much about the revised syntax (I'd switch if it was deemed 
"official"), but the meta-programming part of camlp4 should be valued by 
the team, in my opinion.

When I talk to other programmers in my industry about caml, I mention 
camlp4 as one of the features they should consider when evaluating the 
language relative to other languages.

Chris

"I'd rather write programs to write programs than write programs." - Dick Sites


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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Markus Mottl]

On Thu, 16 May 2002, Daniel de Rauglaudre wrote:
> On Thu, May 16, 2002 at 03:39:45PM -0400, John Prevost wrote:
> > Really?  Why did someone decide that inclusion was a bad idea?
> I say it. Camlp4 and the attempts to improve the syntax have been
> considered *officially* by the OCaml team as a "not serious" work
> and a "loss of time". As I worried about that, and asked for more
> information, it has been confirmed by the team, moreover with several
> personnal attacks.

Sigh. I also don't want to mess with social issues at INRIA, but find
it strange indeed that this is the official line. The only reason
so far why I didn't use camlp4 too often in the past was _because_ it
obviously didn't get enough official support. Its addition to the standard
distribution seemed like a good idea to me. I consider it a very useful
tool for a language that is still a somewhat moving target and which may
require syntax changes in the future. Those could be done with much less
hassle given a powerful tool. Not to mention extensions needed by users.

The syntax question has already been raised here several times so I
don't want to do it again. Suffice it to say that OCaml _has_ syntactic
problems about which beginners stumble frequently as I still remember
from my beginner time and as I can observe with people whom I have just
recently converted. One can get accustomed to and work around those
issues, but this doesn't really make them go away.

Regards,
Markus Mottl

-- 
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Austrian Research Institute
for Artificial Intelligence                  http://www.oefai.at/~markus
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Alessandro Baretta]

Markus Mottl wrote:
> On Thu, 16 May 2002, Daniel de Rauglaudre wrote:
> 
>>On Thu, May 16, 2002 at 03:39:45PM -0400, John Prevost wrote:
>>
>>>Really?  Why did someone decide that inclusion was a bad idea?
>>
>>I say it. Camlp4 and the attempts to improve the syntax have been
>>considered *officially* by the OCaml team as a "not serious" work
>>and a "loss of time". As I worried about that, and asked for more
>>information, it has been confirmed by the team, moreover with several
>>personnal attacks.
> 

FAIW, let me say I'm shedding blood to make my code compile 
when I raise exceptions that have non banal type lists: I 
always misplace my parentheses. I never realized there was 
an alternative syntax provided by CamlP4, but I'm pretty 
sure this must be the solution to my crux. Should this be 
the case, I would find it considerably inconveniencing if 
camlp4 should be removed from the distribution.

Alex Baretta

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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Pierre Weis]

> FAIW, let me say I'm shedding blood to make my code compile 
> when I raise exceptions that have non banal type lists: I 
> always misplace my parentheses.

Have you ever read the programming guidelines that explain the
``secrets'' of Caml parentheses ?

http://pauillac.inria.fr/caml/FAQ/pgl-eng.html

Section IV: When to use parentheses within an expression

If you learn the rules, if you follow those guidelines, and still
experience problems, please let me know, since I used those simple
principles for years with thousands of students (I really mean several
thousands students not several students) and they had no problems once
they had understood and learned those rules.

On the other hand, I agree with you that if you don't know the rules
for parens in Caml, you certainly should have problems to write your
programs. This is the same problems as the one of young people at
school that use to claim that mathematics _HAVE_ (*) syntactic
problems because they never know where to put parens in

1 + 2 * 3

As a teacher, I always said that probably _THEY_ (*) have to learn the
rules first, then use them properly, and then they could criticize the
notations and at the end they will probably could have authority to
claim that mathematics have problems. Fortunately, none of them ever
reached this final step! However, they could have been right in the
first place, and mathematical notation could have to be revisited; for
the time being, nobody cares, every body still have to learn the
meaning of

1 + 2 * 3

Best regards,

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://pauillac.inria.fr/~weis/

(*) In their slang those pupils use upper case letters to mean that
this is true, also to insist that this is not only true but also TRUE,
and even that this is definitely _TRUE_.
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Markus Mottl]

On Fri, 17 May 2002, Pierre Weis wrote:
> Section IV: When to use parentheses within an expression

I know that I should write OCaml-programs rather than participate in
yet another heating debate on syntax, but I just cannot resist...

> If you learn the rules, if you follow those guidelines, and still
> experience problems, please let me know, since I used those simple
> principles for years with thousands of students (I really mean several
> thousands students not several students) and they had no problems once
> they had understood and learned those rules.

It is not an argument in favour of certain syntactic rules that "people
have no problems once they have understood and learned those rules". I
agree that those rules for OCaml are not overly many and can indeed be
understood after some time. But why shouldn't we make this process even
easier by eliminating a few of them or making them simpler to comprehend
and apply?

There are cases where the current syntax can byte you by leading to
programs that compile nicely but exhibit unintended behaviour. This
certainly occurs very, very rarely and can be avoided when the programmer
happens to be in a somewhat sane state of mind. The problem is that
(at least what concerns me ;) the latter is not always the case. Syntax
designers, too, are probably well-advised to follow the principle:
"Never trust human programmers!".

> On the other hand, I agree with you that if you don't know the rules
> for parens in Caml, you certainly should have problems to write your
> programs. This is the same problems as the one of young people at
> school that use to claim that mathematics _HAVE_ (*) syntactic
> problems because they never know where to put parens in

We all have to learn conventions and standards. This does not mean that
all of them are equally clean and concise. To me OCaml is syntactically
much more beautiful than most mainstream languages. Why not let the
latter even further behind in the dust?

This all is not a plea for the Revised Syntax. IMHO, there are some things
it fixes, others that could be fixed differently and cases where we would
still need a fix. I am sure that Daniel would be prepared to discuss
this and eventually "revise the Revised Syntax". But it seems obvious
that syntactic issues are considered a non-topic by the project leaders.

My guess is that it is really pragmatic issues (costs of change; more
urgent issues) that prevent this discussion. If it is so, then why not
be honest about it?  I could live with the argument that you consider
such a step too costly, but have some sense of indirection when syntactic
problems are just discussed away.

Best regards,
Markus Mottl

-- 
Markus Mottl                                             markus@oefai.at
Austrian Research Institute
for Artificial Intelligence                  http://www.oefai.at/~markus
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Pierre Weis]

> On Fri, 17 May 2002, Pierre Weis wrote:
> > Section IV: When to use parentheses within an expression
> 
> I know that I should write OCaml-programs rather than participate in
> yet another heating debate on syntax, but I just cannot resist...

Dear Markus,

You know that I'm not on the side of those that consider syntax as a
minor concern and a waste of time: to you I can say the truth because
I know you will understand it, but please do not tell it to others! In
my mind there is no clear distinction between syntax and semantics. We
very often use syntactic models of theories, hence acknowledging the
fact that difference between syntax and semantics is tenious, subtle,
and more or less a question of point of view (consider for instance
Lisp S-expressions first as abstract syntax trees (syntactic view),
and then as programs and values (semantics view)).

Hence, (to me) there is no question about the fact that semantics
(hence syntax) is of primordial importance. So that we have to improve
the syntax of the language if we can. But we cannot say that the
regular syntax is EXTREMELY ambiguous (with upper case letters and the
like). Be quite, please! It is not ambiguous. You need some parens
sometimes as in math, and math is not known to be that ambiguous.

And we have rules, once again as in math (and generally speaking we
have the same rules, even if we use them in a generalised
manner). This is a good property. The drawback is that you must learn
them; once again as in math.

Considering the difficulties of apprentices, some pedagogical theories
of mathematics once proposed to adopt completely unambiguous (read
absolutely redundant if you want) notations or encodings for algebraic
expressions in mathematics (reverse polish or lisp like parentheses
for operators). This was a complete failure. It happens to be not only
less readable than the usual notation but even much more difficult to
teach, use, and learn!

So, as you know, we have to be careful about those syntax changes: the
best could be worse that the good (as we say in french).

In any way, claiming the Caml syntax is this or that is just useless
and a waste of time. More interesting is to state problems that have
to be solved and axioms (or rules) you want to respect. That's what is
interesting in the revised syntax. Believe it or not, I am glad to see
that it elegantly realizes some of those rules I definitely would like
to have in the syntax of the language; on the other hand it
consistantly violate other of my personal axioms about the syntaxes I
like. It is truly difficult to design a good syntax!

So, what I am interested in is to set up a list of rules to guide the
design of a syntax. This is hard, but interesting and could lead to a
syntax easy to learn and use. This would be constructive and new.

Best regards,

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://pauillac.inria.fr/~weis/


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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Dave Mason]

Although OCaml is probably my favourite language, I get to program in
Java a fair bit (and Scheme a little, but there the syntax is nice and
regular!).

The only syntax error I commonly make in OCaml is that I usually
forget to put parens around the exception and its arguments to a raise
function.  And the problem is exactly that... the raise FUNCTION.
try...with is syntactic, so why shouldn't raise be a statement instead
of a function?  And it wouldn't break many programs (except for a few
unit tests written with FORT).

Then I'd never make any errors in OCaml.  :-)

(In truth, these errors are maybe 10-15% of the type errors I get from
OCaml compilations.  And 90% of the `syntax' errors.)

And if we were looking for things to include in the standard OCaml
distribution, I would nominate FORT.  Unit testing is very important,
and perhaps we could create a culture that regularly shipped unit-test
with their code (as Java is making progress toward).

../Dave
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Pierre Weis]

> Although OCaml is probably my favourite language, I get to program in
> Java a fair bit (and Scheme a little, but there the syntax is nice and
> regular!).
> 
> The only syntax error I commonly make in OCaml is that I usually
> forget to put parens around the exception and its arguments to a raise
> function.  And the problem is exactly that... the raise FUNCTION.
> try...with is syntactic, so why shouldn't raise be a statement instead
> of a function?  And it wouldn't break many programs (except for a few
> unit tests written with FORT).
> Then I'd never make any errors in OCaml.  :-)
> 
> (In truth, these errors are maybe 10-15% of the type errors I get from
> OCaml compilations.  And 90% of the `syntax' errors.)

You are right. Raise was a keyword in Caml for 10 years, just for the
syntactic reasons you mentioned.

With Caml Light, simplicity was the rule (remember that we managed to
run on a 640 ko PC!). So that raise was turn into a primitive function
for sake of simplicity. Afterwards, Objective Caml inherits (:-) that
property of raise.

In 2002, it may be the time to turn raise into a keyword again to
give our beginners and users a more confortable and natural system.

> And if we were looking for things to include in the standard OCaml
> distribution, I would nominate FORT.  Unit testing is very important,
> and perhaps we could create a culture that regularly shipped unit-test
> with their code (as Java is making progress toward).
> 
> ../Dave

I also agree completely with you on the unvaluable importance of
program testing (and also program proving, but this much more
difficult). We plan to write a test generator for Caml
programs. Maxence Guesdon who has industrial experience on testing
volonteers on that project.

Best regards,

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://pauillac.inria.fr/~weis/


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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Diego Olivier Fernandez Pons]

    Bonjour,

Je voulais seulement contribuer avec quelques exemples d'erreurs
auxquelles je me suis confronté et dont l'origine était une mauvaise
compréhension (de ma part) de la syntaxe de Caml.

la première concerne les séquences

val start : int
val coeff : int
val name : string option

method current_state = function () ->
  ["name : " ^ match name with None -> "unknown name" | Some n -> n ;
   "coeff : " ^ string_of_int coeff ;
   "start : " ^ string_of_int start ]

ce qui donne lorsqu'on compile

Warning: this expression should have type unit
method current_state : unit -> string list

En effet, la séquence lie plus fortement que le séparateur d'éléments
dans une liste. Il suffit bien sûr - après avoir réfléchi un bon
moment - de mettre des parenthèses (mieux encore, d'évaluer le nom au
préalable et de concatener avec une constante ensuite)

A ce stade là on peste (quelques instants mais sans rancoeur réelle)
contre Caml pour avoir la mauvaise idée d'utiliser le point virgule
comme séparateur des listes plutôt que la très traditionnelle virgule.

Mais une autre erreur que j'ai commise plus d'une fois m'indique
immédiatement pourquoi c'est le cas :

[1, 2, 3] s'évalue en (int * int * int) list = [(1, 2, 3)]

car x, y est considérée comme une paire, d'où l'autre erreur qui m'a
perturbé pendant un certain temps

type term =
  | Constant of string * int
  | Variable of string
  | Apply of term * term list

let unify_terms env = function term1 term2 ->
  match (term1, term2) with
  | (Constant x, Constant y) -> (x = y, env)
  | (Variable x, Variable y) when x = y -> (true, env)
  | (Variable x, Variable y) -> (true, (x, Variable y) :: env)
  | (const, Variable _ as var) -> unify_terms env var const
etc.

This expression has type term * term but is here used with type term

C'est encore un problème de parenthèses, il faut s'habituer au fait
que x, y as value et (x, y) as value s'évaluent de la même façon.

        Diego Olivier
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Markus Mottl]

Dear Pierre,

On Fri, 17 May 2002, Pierre Weis wrote:
> Hence, (to me) there is no question about the fact that semantics (hence
> syntax) is of primordial importance. So that we have to improve the
> syntax of the language if we can. But we cannot say that the regular
> syntax is EXTREMELY ambiguous (with upper case letters and the like). Be
> quite, please! It is not ambiguous. You need some parens sometimes as
> in math, and math is not known to be that ambiguous.

I am not sure whether you, as one of the language designers, felt offended
by my use of an _emphasis_. If yes, it seems to be a misunderstanding,
because I just wanted to point out the fact that "there _are_ problems"
rather than that there was anything extremely ambiguous about OCaml, which
would certainly be unjustified criticism. The problems are comparatively
minor, but they do exist and therefore shouldn't be brushed under the
carpet but (IMHO) solved at some point in the future. That's all I wanted
to say.

> Considering the difficulties of apprentices, some pedagogical theories
> of mathematics once proposed to adopt completely unambiguous (read
> absolutely redundant if you want) notations or encodings for algebraic
> expressions in mathematics (reverse polish or lisp like parentheses
> for operators). This was a complete failure. It happens to be not only
> less readable than the usual notation but even much more difficult to
> teach, use, and learn!

I wouldn't say that e.g. RPN were "absolutely redundant". In fact, I
think the reason why it wasn't so successful is exactly because it isn't
redundant: humans just need some redundant syntactic hints to parse
texts more efficiently. In the case of RPN it is actually impossible
to interpret or correctly modify only a part of an expression without
having parsed it from the beginning. This makes both understanding and
editing very difficult.

Just to give an example, I like the fact that the following is
syntactically redundant in OCaml:

  let f = function X -> () | Y -> ()

and

  let f = function | X -> () | Y -> ()

This way I can more easily choose whether I want to put the whole code in
one line or each match in a separate one. Without allowing a preceding
"|" in the first line of a match it would be annoying to add matches at
the beginning or move the first one elsewhere.

OTOH, I really dislike the lack of distinction between constructors with
tuple arguments and several arguments (as Brian has also mentioned).

Or the following irregularity:

  try ()
  with Exit -> print_string "Hello "; print_endline "world!";
  print_endline "DONE"

and

  if false then print_string "Hello "; print_endline "world!";
  print_endline "DONE"

The catch here is that users can accidently write suggestive code,
which makes people believe that "DONE" will be printed in any case as
in the "try/with"-example or that "world!" would be printed only if the
condition were true in the "if/then/else" example.

A simple-minded fix does not resolve all problems:

  try ()
  with Exit -> (print_string "Hello "; print_endline "world!");
  print_endline "DONE"

This will still not print "DONE"! But here the behaviour changes:

  if false then (print_string "Hello "; print_endline "world!");
  print_endline "DONE"

I think this is just confusing. IMHO, "try/with" and "if/then/else" should
really syntactically force users to explicitly express what they mean. To
prevent myself from falling into such traps I have adopted the strategy
to never use ";" in code parts that are executed conditionally: I use
"let _ = ... in" instead, which doesn't look particularly beautiful, but
which I can still parse successfully even when being in brain-dead mode.

The upper case is particularly bad, because the compiler cannot help you.
But there are similar ones that are annoying, but are at least caught
at compile time, e.g.:

  match v1 with
  | A ->
      match v2 with
      | X -> ()
      | Y -> ()
  | B -> ()

Then there is this question of when to use ";;", which all beginners
wonder about...

> In any way, claiming the Caml syntax is this or that is just useless
> and a waste of time. More interesting is to state problems that have
> to be solved and axioms (or rules) you want to respect.

People are certainly willing to discuss details of syntactic aspects
they find confusing. AFAIK, it's almost always the same kind of problems.

> That's what is interesting in the revised syntax. Believe it or not,
> I am glad to see that it elegantly realizes some of those rules I
> definitely would like to have in the syntax of the language; on the
> other hand it consistantly violate other of my personal axioms about
> the syntaxes I like. It is truly difficult to design a good syntax!

I certainly agree that designing a good syntax is quite challeninging.
Another reason why we should think about it - who doesn't like being
challenged :-)

> So, what I am interested in is to set up a list of rules to guide the
> design of a syntax. This is hard, but interesting and could lead to a
> syntax easy to learn and use. This would be constructive and new.

What I consider at least as important is how to introduce syntactic
changes into a language without driving users mad.  This gets us back
to the topic of having camlp4 in the distribution or not. I think that
irrespective of the syntactic rules the community can finally agree on,
a tool like camlp4 would be very welcome to support a transition.

Best regards,
Markus Mottl

-- 
Markus Mottl                                             markus@oefai.at
Austrian Research Institute
for Artificial Intelligence                  http://www.oefai.at/~markus
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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[james woodyatt]

On Sunday, May 19, 2002, at 04:31 AM, Markus Mottl wrote:
> [...]
> What I consider at least as important is how to introduce syntactic
> changes into a language without driving users mad.  This gets us back
> to the topic of having camlp4 in the distribution or not. I think that
> irrespective of the syntactic rules the community can finally agree on,
> a tool like camlp4 would be very welcome to support a transition.

I'd like to go on record as agreeing with what Markus wrote about syntax 
issues in Ocaml in the message excerpted above.  In addition, the 
paragraph I chose to quote represents an opinion that I, too, hold quite 
strongly.


--
j h woodyatt <jhw@wetware.com>
"The plainest print cannot be read through a solid gold sovereign,
or a ruble, or a golden eagle." --sam cummings, famous arms dealer

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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Alessandro Baretta]

Pierre Weis wrote:
>>FAIW, let me say I'm shedding blood to make my code compile 
>>when I raise exceptions that have non banal type lists: I 
>>always misplace my parentheses.
> 
> 
> Have you ever read the programming guidelines that explain the
> ``secrets'' of Caml parentheses ?
> 
> http://pauillac.inria.fr/caml/FAQ/pgl-eng.html
> 
> Section IV: When to use parentheses within an expression
> 
> If you learn the rules, if you follow those guidelines, and still
> experience problems, please let me know, since I used those simple
> principles for years with thousands of students (I really mean several
> thousands students not several students) and they had no problems once
> they had understood and learned those rules.

Thanks for mentioning them. All the documentation I have on 
Ocaml now is the "official" html manual, but the syntax part 
is not human-readable. I was never actually taught Ocaml, 
but rather I learned it (if I ever did) by writing code and 
trying to get it to compile. I never had problems figuring 
out the meaning and usage of type lists in constructors, 
with the sole exception of exceptions. Somehow, they have 
always escaped my inductive learning ability. I'll try 
reading the guidelines.

> On the other hand, I agree with you that if you don't know the rules
> for parens in Caml, you certainly should have problems to write your
> programs. This is the same problems as the one of young people at
> school that use to claim that mathematics _HAVE_ (*) syntactic
> problems because they never know where to put parens in

I have absolutely no authority to criticize the syntax; I 
just claim that some aspects of it are not user-friendly. 
Math transcends user-friendliness. It simply is not meant to 
be used in any definite way. It just sits there, exists. (I 
once heard an algebraist wonder if category theory had any 
*real* use.) Software systems, on the other hand, must be 
used by humans in order to be worth creating, and, for this 
reason, they ought to be as intuitive as possible. I still 
have not had time to mess with CamlP4 and cannot say much 
about it, but if its syntax is more intuitive than the 
native one, then welcome CamlP4.

Regards,
Alex Baretta

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Re: [Caml-list] Camlp4/OCaml [was: Generating C stubs]

[Daniel de Rauglaudre]

Hi,

On Fri, May 17, 2002 at 04:12:28AM +0000, Brian Rogoff wrote:

> I dread the prospect of a flamewar over this, but I think that removing
> CamlP4 from OCaml is a very bad idea, and a step backwards. Bad news to
> me, indeed...

Right. Divorce is generally a bad idea, but the solution when the
marriage have been done with a bad preparation and lies.

> I would encourage reconsidering this decision. Note that for any
> given feature beyond core ML (labels, variants, objects, higher
> order functors, ...)  I can imagine someone considering that feature
> "not serious".

No decision is definitive, I can change my mind, but I have asked for
propositions since two months, and nothing happened. Separation is the
best compromise I found. If somebody has a better solution (except
hide the problem under the carpet), I am ready to hear it.

-- 
Daniel de RAUGLAUDRE
daniel.de_rauglaudre@inria.fr
http://cristal.inria.fr/~ddr/
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