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