[Caml-list] view types in ocaml?

[Caml-list] view types in ocaml?

[Ed L Cashin]

Hi.  I like ocamlbrowser well enough, but is there a way to view type
info right from the interactive ocaml prompt.  Here's what I'm
thinking of (which won't work, of course).

          Objective Caml version 3.06
  
  # #load "unix.cma";;
  # Unix.LargeFile.lseek;;
  - : Unix.file_descr -> int64 -> Unix.seek_command -> int64 = <fun>
  # Unix.LargeFile.stats;;
  type stats = {
    st_dev : int;
    st_ino : int;
    st_kind : Unix.file_kind;
    st_perm : Unix.file_perm;
    st_nlink : int;
    st_uid : int;
    st_gid : int;
    st_rdev : int;
    st_size : int64;
    st_atime : float;
    st_mtime : float;
    st_ctime : float;
  } 

-- 
--Ed L Cashin            |   PGP public key:
  ecashin@uga.edu        |   http://noserose.net/e/pgp/
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Re: [Caml-list] view types in ocaml?

[Yaron M. Minsky]

Speaking of suggestions for toplevel improvements, I've got a couple:

- don't print really long strings.
        
        The mechanism for ensuring that overly long things don't get
        printed to the screen apparently doesn't work for strings.  The
        result is that if you do anything with a large string (say,
        allocate a 100K buffer), every character gets printed to the
        screen.  (and if that buffer is mostly zeros, each buffer
        character is printed as '\000', taking 4 characters.  Argh!)
        
- don't print let-bound values
        
        If I type an expression, such "let x = foobar a b c", the value
        of x is dumped to the screen.  This is contrary to the behavior
        of most language interpreters (see python or matlab for
        examples.)  It means you have no way of supressing the printing
        of the values you generate, which is quite inconvenient. 
        Perhaps the type should always be printed (although maybe not),
        but printing the value every time make no sense.

Suggestively,
y


On Mon, 2003-01-20 at 20:14, Ed L Cashin wrote:
> Hi.  I like ocamlbrowser well enough, but is there a way to view type
> info right from the interactive ocaml prompt.  Here's what I'm
> thinking of (which won't work, of course).
> 
>           Objective Caml version 3.06
>   
>   # #load "unix.cma";;
>   # Unix.LargeFile.lseek;;
>   - : Unix.file_descr -> int64 -> Unix.seek_command -> int64 = <fun>
>   # Unix.LargeFile.stats;;
>   type stats = {
>     st_dev : int;
>     st_ino : int;
>     st_kind : Unix.file_kind;
>     st_perm : Unix.file_perm;
>     st_nlink : int;
>     st_uid : int;
>     st_gid : int;
>     st_rdev : int;
>     st_size : int64;
>     st_atime : float;
>     st_mtime : float;
>     st_ctime : float;
>   } 

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Re: [Caml-list] view types in ocaml?

[Yaron M. Minsky]

On Tue, 2003-01-21 at 08:46, Oliver Bandel wrote:

> 
> Well, I think that it is very good to have the values printed
> always.
> 
> I like that.
> 
> The toplevel is very good for testing code and doing
> experiments - and therefore it is very good to have
> the values printed always.

For the record, my suggestion is only that let-bound value printing
should be suppressed.  You could always see the result by just not
binding it (e.g., typing "foo x y z" instead of "let a = foo x y z".) 
And you can always get the contents of any variable printed by typing
it's name on the command line (e.g. "a;;" to see the contents of
variable a).

> If I don't need such helpers and code my code directly,
> I can write it into a file and let ocamlc or
> ocamlopt do its work.

But if you're doing interactive work with data of non-trivial size, the
constant printing is real pain.  I do an enormous amount of work
interactively at the command line, and more often than not, the data
structure print-outs are so long that I can't see the line I just typed
into the interpreter. 

> But maybe it makes sense to have options in the toplevel
> to disable such printings.

Making the suppression controllable by command-line options is
sensible.  But I do think that it should be the default.  There's a
reason that most language interpreters have this suppression, and I
don't think there's anything special about ocaml that makes it different
in this regard.

Another useful extension to the ocaml toplevel which has been proposed
in the past is to have some kind of default "this" variable which stores
unbound variables.  That would make the supression of let-bound easier
to use, since if you wanted to see how something printed out, you could
refrain from let-binding it, and still get access to the result using
the "this" variable.

> But it is no good idea to disable it hardcoded.
> 
> I prefer the possibility to have such printings,
> but think optionally turining it off would be ok.
> 
> Ciao,
>    Oliver

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Re: [Caml-list] view types in ocaml?

[Gérard Huet]

Le mardi, 21 jan 2003, à 15:42 Europe/Paris, Yaron M. Minsky a écrit :

> Another useful extension to the ocaml toplevel which has been proposed
> in the past is to have some kind of default "this" variable which 
> stores
> unbound variables.  That would make the supression of let-bound easier
> to use, since if you wanted to see how something printed out, you could
> refrain from let-binding it, and still get access to the result using
> the "this" variable.

For the record, this facility existed in the original ML from LCF 20 
years ago,
the variable was called "it" and it was extremely useful in top-level 
debugging.
It was still there in ML V6.2 circa 1985, and thus also in early 
versions of Caml.
I do not remember who took "it" off, but maybe "it" could be 
resurrected...
GH


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[Caml-list] view types in ocaml?

[Ed L Cashin]

Hi.  I like ocamlbrowser well enough, but is there a way to view type
info right from the interactive ocaml prompt?

Here's what I'm thinking of (which won't work, of course).

          Objective Caml version 3.06
  
  # #load "unix.cma";;
  # Unix.LargeFile.lseek;;
  - : Unix.file_descr -> int64 -> Unix.seek_command -> int64 = <fun>
  # Unix.LargeFile.stats;;
  type stats = {
    st_dev : int;
    st_ino : int;
    st_kind : Unix.file_kind;
    st_perm : Unix.file_perm;
    st_nlink : int;
    st_uid : int;
    st_gid : int;
    st_rdev : int;
    st_size : int64;
    st_atime : float;
    st_mtime : float;
    st_ctime : float;
  } 


-- 
--Ed L Cashin            |   PGP public key:
  cashin@cs.uga.edu        |   http://noserose.net/e/pgp/

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Re: [Caml-list] view types in ocaml?

[Remi VANICAT]

Ed L Cashin <cashin@cs.uga.edu> writes:

> Hi.  I like ocamlbrowser well enough, but is there a way to view type
> info right from the interactive ocaml prompt?
>
> Here's what I'm thinking of (which won't work, of course).
>
>           Objective Caml version 3.06
>   
>   # #load "unix.cma";;
>   # Unix.LargeFile.lseek;;
>   - : Unix.file_descr -> int64 -> Unix.seek_command -> int64 = <fun>
>   # Unix.LargeFile.stats;;
>   type stats = {
>     st_dev : int;

[...]

>     st_ctime : float;
>   } 

well, there is alway the module redefinition trick :

  # module M = Unix.LargeFile;;
   module M :
     sig
       val lseek : Unix.file_descr -> int64 -> Unix.seek_command -> int64

[...]

    type stats =
      Unix.LargeFile.stats = {
      st_dev : int;

[...]

      st_ctime : float;
    }
    val stat : string -> stats
    val lstat : string -> stats
    val fstat : Unix.file_descr -> stats
  end


of course, for very big module, this is not a solution.

-- 
Rémi Vanicat
vanicat@labri.u-bordeaux.fr
http://dept-info.labri.u-bordeaux.fr/~vanicat
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Re: [Caml-list] view types in ocaml?

[Ed L Cashin]

Remi VANICAT <vanicat@labri.u-bordeaux.fr> writes:

...
> well, there is alway the module redefinition trick :
> 
>   # module M = Unix.LargeFile;;
[shows sig]

That's great.  Thanks.

...
> of course, for very big module, this is not a solution.

I'm using run-caml in emacs, so it's still very helpful for, e.g., the
whole Unix module.

-- 
--Ed L Cashin            |   PGP public key:
  ecashin@uga.edu        |   http://noserose.net/e/pgp/
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