[Caml-list] getting the name of a function from its body

[Caml-list] getting the name of a function from its body

[Gustave Nimant]

Hello,

is there any way in OCaml to get the name of a function from its body, 
in order to write precise error messages for instance ?

Regards
Gustave

Re: [Caml-list] getting the name of a function from its body

[Fabrice Le Fessant]

Recent versions of OCaml provide "__LOC__", "__FILE__", "__LINE__",
"__MODULE__" and "__POS__" primitives that can be used to display
precise error messages.

--Fabrice

On Mon, Jun 1, 2015 at 1:42 PM, Gustave Nimant <gustave.nimant@free.fr> wrote:
> Hello,
>
> is there any way in OCaml to get the name of a function from its body, in
> order to write precise error messages for instance ?
>
> Regards
> Gustave
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs



-- 
Fabrice LE FESSANT
Chercheur en Informatique
INRIA Paris Rocquencourt -- OCamlPro
Programming Languages and Distributed Systems

Re: [Caml-list] getting the name of a function from its body

[Gabriel Scherer]

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"Recent" is 4.02 in that case -- although the implementors forgot to
indicate it as such using @since tags in the documentation.

On Mon, Jun 1, 2015 at 1:46 PM, Fabrice Le Fessant <
Fabrice.Le_fessant@inria.fr> wrote:

> Recent versions of OCaml provide "__LOC__", "__FILE__", "__LINE__",
> "__MODULE__" and "__POS__" primitives that can be used to display
> precise error messages.
>
> --Fabrice
>
> On Mon, Jun 1, 2015 at 1:42 PM, Gustave Nimant <gustave.nimant@free.fr>
> wrote:
> > Hello,
> >
> > is there any way in OCaml to get the name of a function from its body, in
> > order to write precise error messages for instance ?
> >
> > Regards
> > Gustave
> >
> > --
> > Caml-list mailing list.  Subscription management and archives:
> > https://sympa.inria.fr/sympa/arc/caml-list
> > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> > Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>
>
> --
> Fabrice LE FESSANT
> Chercheur en Informatique
> INRIA Paris Rocquencourt -- OCamlPro
> Programming Languages and Distributed Systems
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>

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Re: [Caml-list] getting the name of a function from its body

[Gustave Nimant]

On 01/06/2015 13:46, Fabrice Le Fessant wrote:
> Recent versions of OCaml provide "__LOC__", "__FILE__", "__LINE__",
> "__MODULE__" and "__POS__" primitives that can be used to display
> precise error messages.
>
> --Fabrice
Thank you for this information I was not aware of.
It seems that the functions described in
http://caml.inria.fr/pub/docs/manual-ocaml/libref/Pervasives.html
do not answer my question :
"how to get the name of the current function ?"

Do I miss something ?

Gustave

Re: [Caml-list] getting the name of a function from its body

[Francois Berenger]

On 06/01/2015 06:36 PM, Gustave Nimant wrote:
> On 01/06/2015 13:46, Fabrice Le Fessant wrote:
>> Recent versions of OCaml provide "__LOC__", "__FILE__", "__LINE__",
>> "__MODULE__" and "__POS__" primitives that can be used to display
>> precise error messages.
>>
>> --Fabrice
> Thank you for this information I was not aware of.
> It seems that the functions described in
> http://caml.inria.fr/pub/docs/manual-ocaml/libref/Pervasives.html
> do not answer my question :
> "how to get the name of the current function ?"

It is currently not possible.

There is no __FUNCTION__ like you have in C.
I was also quite interested by this feature a long time ago.
For loggers it is quite useful.

I cannot find the thread back, I don't know where to search the archives
of caml-list.
Gabriel Scherer mentioned there is not always a function name since
they can be inlined by the compiler, if I remember correctly.

> Do I miss something ?
>
> Gustave
>

-- 
Regards,
Francois.

Re: [Caml-list] getting the name of a function from its body

[Gustave Nimant]

On 01/06/2015 18:46, Francois Berenger wrote:
>>
>> It seems that the functions described in
>> http://caml.inria.fr/pub/docs/manual-ocaml/libref/Pervasives.html
>> do not answer my question :
>> "how to get the name of the current function ?"
>
> It is currently not possible.
>
> There is no __FUNCTION__ like you have in C.
> I was also quite interested by this feature a long time ago.
> For loggers it is quite useful.
>
> I cannot find the thread back, I don't know where to search the archives
> of caml-list.
> Gabriel Scherer mentioned there is not always a function name since
> they can be inlined by the compiler, if I remember correctly.
I hope the argument of the inlining case is not serious, is it ?

Best,
Gustave

Re: [Caml-list] getting the name of a function from its body

[Yotam Barnoy]

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The argument makes no sense since inlining would also affect MODULE, FILE,
etc. It seems more like an omission.

-Yotam

On Mon, Jun 1, 2015 at 1:38 PM, Gustave Nimant <gustave.nimant@free.fr>
wrote:

> On 01/06/2015 18:46, Francois Berenger wrote:
>
>>
>>> It seems that the functions described in
>>> http://caml.inria.fr/pub/docs/manual-ocaml/libref/Pervasives.html
>>> do not answer my question :
>>> "how to get the name of the current function ?"
>>>
>>
>> It is currently not possible.
>>
>> There is no __FUNCTION__ like you have in C.
>> I was also quite interested by this feature a long time ago.
>> For loggers it is quite useful.
>>
>> I cannot find the thread back, I don't know where to search the archives
>> of caml-list.
>> Gabriel Scherer mentioned there is not always a function name since
>> they can be inlined by the compiler, if I remember correctly.
>>
> I hope the argument of the inlining case is not serious, is it ?
>
> Best,
> Gustave
>
>
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>

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Re: [Caml-list] getting the name of a function from its body

[Fabrice Le Fessant]

The main reason for the absence of __FUNCTION__ is probably that it
does not really make sense : you might have several functions with the
same name within the same module :

let f x = x+1
let f list = List.map f list

It makes sense in C, because you can only define a symbol once in a
file, so the pair (__FILE__, __FUNCTION__) is uniq (and if the
function is not static, it is probably even uniq within the
executable).

In OCaml, it is probably better to use the pair (__FILE__, __LINE__)
to tell the dev where to search for the problem.

--Fabrice





On Mon, Jun 1, 2015 at 6:36 PM, Gustave Nimant <gustave.nimant@free.fr> wrote:
> On 01/06/2015 13:46, Fabrice Le Fessant wrote:
>>
>> Recent versions of OCaml provide "__LOC__", "__FILE__", "__LINE__",
>> "__MODULE__" and "__POS__" primitives that can be used to display
>> precise error messages.
>>
>> --Fabrice
>
> Thank you for this information I was not aware of.
> It seems that the functions described in
> http://caml.inria.fr/pub/docs/manual-ocaml/libref/Pervasives.html
> do not answer my question :
> "how to get the name of the current function ?"
>
> Do I miss something ?
>
>
> Gustave
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs



-- 
Fabrice LE FESSANT
Chercheur en Informatique
INRIA Paris Rocquencourt -- OCamlPro
Programming Languages and Distributed Systems

Re: [Caml-list] getting the name of a function from its body

[Francois Berenger]

On 06/01/2015 11:57 PM, Fabrice Le Fessant wrote:
> The main reason for the absence of __FUNCTION__ is probably that it
> does not really make sense : you might have several functions with the
> same name within the same module :
>
> let f x = x+1
> let f list = List.map f list
>
> It makes sense in C, because you can only define a symbol once in a
> file, so the pair (__FILE__, __FUNCTION__) is uniq (and if the
> function is not static, it is probably even uniq within the
> executable).
>
> In OCaml, it is probably better to use the pair (__FILE__, __LINE__)
> to tell the dev where to search for the problem.

Then, the triplet (__FILE__, __LINE__, __FUNCTION__) is unique in OCaml.

The problem I saw a long time ago while working with people who were not 
programmers (but still scientits)
is that they have more chance to fix an error in one of their input
file when given the function name than when not.

And since I created and maintain a logging library in OCaml, I was (and 
I am still) interested into making log messages as useful as possible to 
end users.

> --Fabrice
>
>
>
>
>
> On Mon, Jun 1, 2015 at 6:36 PM, Gustave Nimant <gustave.nimant@free.fr> wrote:
>> On 01/06/2015 13:46, Fabrice Le Fessant wrote:
>>>
>>> Recent versions of OCaml provide "__LOC__", "__FILE__", "__LINE__",
>>> "__MODULE__" and "__POS__" primitives that can be used to display
>>> precise error messages.
>>>
>>> --Fabrice
>>
>> Thank you for this information I was not aware of.
>> It seems that the functions described in
>> http://caml.inria.fr/pub/docs/manual-ocaml/libref/Pervasives.html
>> do not answer my question :
>> "how to get the name of the current function ?"
>>
>> Do I miss something ?
>>
>>
>> Gustave
>>
>> --
>> Caml-list mailing list.  Subscription management and archives:
>> https://sympa.inria.fr/sympa/arc/caml-list
>> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>
>

-- 
Regards,
Francois.

Re: [Caml-list] getting the name of a function from its body

[Jacques Garrigue]

On 2015/06/02 17:10, Francois Berenger wrote:
> 
> On 06/01/2015 11:57 PM, Fabrice Le Fessant wrote:
>> The main reason for the absence of __FUNCTION__ is probably that it
>> does not really make sense : you might have several functions with the
>> same name within the same module :
>> 
>> let f x = x+1
>> let f list = List.map f list
>> 
>> It makes sense in C, because you can only define a symbol once in a
>> file, so the pair (__FILE__, __FUNCTION__) is uniq (and if the
>> function is not static, it is probably even uniq within the
>> executable).
>> 
>> In OCaml, it is probably better to use the pair (__FILE__, __LINE__)
>> to tell the dev where to search for the problem.
> 
> Then, the triplet (__FILE__, __LINE__, __FUNCTION__) is unique in OCaml.
> 
> The problem I saw a long time ago while working with people who were not programmers (but still scientits)
> is that they have more chance to fix an error in one of their input
> file when given the function name than when not.
> 
> And since I created and maintain a logging library in OCaml, I was (and I am still) interested into making log messages as useful as possible to end users.


You make a good point here.
The subtlety however is that it would require keeping track of the enclosing function name in the compiler, which is not done at all currently.
Also, this feature would require some kind of specification: I suppose by function you mean the enclosing toplevel let, but we also have the case of classes, where the occurence might be in the initialization part or inside a method, and of course cases where the definition has no name (toplevel expression of pattern-matching with several components).
Also should we do something special for submodules? functors?
Anything may be better than nothing, but this ends up being clearly more complex than __FILE__ and __LINE__, which come directly from the parser and are readily available in the syntax tree.

Jacques

Re: [Caml-list] getting the name of a function from its body

[Romain Bardou]

On 02/06/2015 10:21, Jacques Garrigue wrote:
> On 2015/06/02 17:10, Francois Berenger wrote:
>>
>> On 06/01/2015 11:57 PM, Fabrice Le Fessant wrote:
>>> The main reason for the absence of __FUNCTION__ is probably that it
>>> does not really make sense : you might have several functions with the
>>> same name within the same module :
>>>
>>> let f x = x+1
>>> let f list = List.map f list
>>>
>>> It makes sense in C, because you can only define a symbol once in a
>>> file, so the pair (__FILE__, __FUNCTION__) is uniq (and if the
>>> function is not static, it is probably even uniq within the
>>> executable).
>>>
>>> In OCaml, it is probably better to use the pair (__FILE__, __LINE__)
>>> to tell the dev where to search for the problem.
>>
>> Then, the triplet (__FILE__, __LINE__, __FUNCTION__) is unique in OCaml.
>>
>> The problem I saw a long time ago while working with people who were not programmers (but still scientits)
>> is that they have more chance to fix an error in one of their input
>> file when given the function name than when not.
>>
>> And since I created and maintain a logging library in OCaml, I was (and I am still) interested into making log messages as useful as possible to end users.
>
>
> You make a good point here.
> The subtlety however is that it would require keeping track of the enclosing function name in the compiler, which is not done at all currently.
> Also, this feature would require some kind of specification: I suppose by function you mean the enclosing toplevel let, but we also have the case of classes, where the occurence might be in the initialization part or inside a method, and of course cases where the definition has no name (toplevel expression of pattern-matching with several components).
> Also should we do something special for submodules? functors?
> Anything may be better than nothing, but this ends up being clearly more complex than __FILE__ and __LINE__, which come directly from the parser and are readily available in the syntax tree.
>
> Jacques
>

Another possibility is to be able to write __FUNCTIONS__, which would be 
a map/hashtbl/whatever from __LINE__ to function names, for the current 
file (or maybe module).

Example:

let log line s =
   Printf.printf "File %s, function %s, line %d: %s" __FILE__
     (Int_map.find line __FUNCTIONS__) line s

let test () =
   log __LINE__ "hello"

Well this example does not quite work because __LINE__ is not actually 
the line number of function test, so we actually need to find the 
biggest function line number which is less than __LINE__.

The user could also improve backtraces thanks to this. He would add "let 
functions = __FUNCTIONS__" in all his files, then he would parse the 
backtrace string to get file names and line numbers, and finally he 
would find the function name for each file name and line number.

I have no idea whether it is a good idea or not. But I guess 
__FUNCTIONS__ can be generated from the typed tree of a module, making 
it easier to implement than __FUNCTION__? Basically, add __FUNCTIONS__ 
in the environment before typing, and generate its actual value after 
typing.

Cheers,

-- 
Romain Bardou

Re: [Caml-list] getting the name of a function from its body

[Damien Doligez]

On Tue, Jun 2, 2015 at 4:10 AM, Francois Berenger
<francois.berenger@inria.fr> wrote:

> Then, the triplet (__FILE__, __LINE__, __FUNCTION__) is unique in OCaml.

No, because you can be in several functions at the same time, or in a
function that has no name, or even in several nameless functions. This
has nothing to do with inlining or any compilation technique, it's
about the language itself.

-- Damien

Re: [Caml-list] getting the name of a function from its body

[Gerd Stolpmann]

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You can also put several functions on the same line... The argument does
not make much sense. It is eventually up to the developer of a module to
ensure that error messages are unique (enough).

I guess it is simply an implementation issue. The name of the current
function is not at hand where this kind of macros is expanded.

Gerd

Am Montag, den 01.06.2015, 23:57 +0200 schrieb Fabrice Le Fessant:
> The main reason for the absence of __FUNCTION__ is probably that it
> does not really make sense : you might have several functions with the
> same name within the same module :
> 
> let f x = x+1
> let f list = List.map f list
> 
> It makes sense in C, because you can only define a symbol once in a
> file, so the pair (__FILE__, __FUNCTION__) is uniq (and if the
> function is not static, it is probably even uniq within the
> executable).
> 
> In OCaml, it is probably better to use the pair (__FILE__, __LINE__)
> to tell the dev where to search for the problem.
> 
> --Fabrice
> 
> 
> 
> 
> 
> On Mon, Jun 1, 2015 at 6:36 PM, Gustave Nimant <gustave.nimant@free.fr> wrote:
> > On 01/06/2015 13:46, Fabrice Le Fessant wrote:
> >>
> >> Recent versions of OCaml provide "__LOC__", "__FILE__", "__LINE__",
> >> "__MODULE__" and "__POS__" primitives that can be used to display
> >> precise error messages.
> >>
> >> --Fabrice
> >
> > Thank you for this information I was not aware of.
> > It seems that the functions described in
> > http://caml.inria.fr/pub/docs/manual-ocaml/libref/Pervasives.html
> > do not answer my question :
> > "how to get the name of the current function ?"
> >
> > Do I miss something ?
> >
> >
> > Gustave
> >
> > --
> > Caml-list mailing list.  Subscription management and archives:
> > https://sympa.inria.fr/sympa/arc/caml-list
> > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> > Bug reports: http://caml.inria.fr/bin/caml-bugs
> 
> 
> 
> -- 
> Fabrice LE FESSANT
> Chercheur en Informatique
> INRIA Paris Rocquencourt -- OCamlPro
> Programming Languages and Distributed Systems
> 

-- 
------------------------------------------------------------
Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
My OCaml site:          http://www.camlcity.org
Contact details:        http://www.camlcity.org/contact.html
Company homepage:       http://www.gerd-stolpmann.de
------------------------------------------------------------


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[Caml-list] Getting the list of available function within a module

[Nicolas Ratier]

Hello,

I'm writing a syntax highlighting definition file for OCaml and
I need some help to generate automatically the keywords.

How to get the string list of all installed module inside a OCaml program?

How to get the string list of all available functions within a module.
For instance : for the module Unix get the list:
["error_message";"handle_unix_error";"environment";...;"setsid"]

Is there an OCaml module to handle interface information of a OCaml module?
(Some programs, like ocamlbrowser must do it this kind of things).

Thanks,
Nicolas