Thanks Fabrice, this perfectly explains what I observe. Is this behavior
considered the right one? Reading from a pipe is regretfully not an option
for me, as my script has command line arguments. Hence when I type:

cat script.ml | ocaml --foo --bar 1

the toplevel complains it knows nothing about the arguments foo and bar. A
"--" argument would be useful but it seems not available. If it's so, I'll
file a feature request on Mantis, since without it, there seems to be no
way to give a script to the toplevel that both takes command line arguments
and uses a syntax extension.

Thanks again!



2014-07-02 10:08 GMT+02:00 Fabrice Le Fessant <Fabrice.Le_fessant@inria.fr>:

> If I remember well, I think "ocaml" has a different behavior depending on
> what it reads from:
> * From a pipe, it parses every sentence and execute each one immediatly.
> * From a file, it tries to parse the whole file, and then executes
> everything.
>
> In the second case, it means it will only execute the load of the syntax
> extension after parsing the whole file... which will fail, since the syntax
> extension is needed for that.
>
> --Fabrice
> INRIA & OCamlPro
>
>
>
> On Tue, Jul 1, 2014 at 7:06 PM, Philippe Veber <philippe.veber@gmail.com>
> wrote:
>
>> Thanks David!
>>
>> The first call fails with a syntax error on "with sexp":
>>
>> [pbil:~ 18:58]$cat rien.ml
>>
>> let () =
>>   try Topdirs.dir_directory (Sys.getenv "OCAML_TOPLEVEL_PATH")
>>   with Not_found -> ()
>> ;;
>>
>> #use "topfind";;
>> #camlp4o;;
>> #require " sexplib.syntax";;
>>
>> open Sexplib.Std;;
>>
>> type t = int with sexp;;
>>
>> [pbil:~ 18:58]$ocaml rien.ml
>> File "rien.ml", line 12, characters 13-17:
>> Error: Syntax error
>>
>> It seems like the sexp syntax extension is not loaded when the script is
>> evaluated. But it's not really clear to me what going wrong...
>>
>> Cheers!
>> ph.
>>
>>
>>
>> 2014-07-01 18:51 GMT+02:00 David Sheets <sheets@alum.mit.edu>:
>>
>> On Tue, Jul 1, 2014 at 5:38 PM, Philippe Veber <philippe.veber@gmail.com>
>>> wrote:
>>> > Reposting this question here, just in case.
>>> >
>>> > ---------- Forwarded message ----------
>>> > From: Philippe Veber <philippe.veber@gmail.com>
>>> > Date: 2014-06-28 21:32 GMT+02:00
>>> > Subject: Toplevel and syntax extension.
>>> > To: ocaml_beginners@yahoogroups.com
>>> >
>>> >
>>> > Dear camlers,
>>> >
>>> > Consider the following script:
>>> >
>>> > #use "topfind";;
>>> > #camlp4o;;
>>> > #require "sexplib.syntax";;
>>> >
>>> > open Sexplib.Std;;
>>> >
>>> > type t = int with sexp;;
>>> >
>>> > Saved as script.ml, the simple call:
>>> >
>>> > ocaml script.ml
>>> >
>>> > fails while the call:
>>> >
>>> > cat script.ml | ocaml
>>> >
>>> > succeeds. Any idea how I could fix the first call?
>>>
>>> How does the first call fail? A difference between the two is that, in
>>> the second, the .ocamlinit file is used. If you are using opam with
>>> ocamlfind installed via it, this file will contain your Topdirs setup.
>>> You can try:
>>>
>>> let () =
>>>   try Topdirs.dir_directory (Sys.getenv "OCAML_TOPLEVEL_PATH")
>>>   with Not_found -> ()
>>> ;;
>>>
>>> at the top of your script (after hashbang but before directives).
>>>
>>> Hope this helps,
>>>
>>> David
>>>
>>
>>
>
>
> --
> Fabrice LE FESSANT
> Chercheur en Informatique
> INRIA Paris Rocquencourt -- OCamlPro
> Programming Languages and Distributed Systems
>