Compiling .ml containing toplevel directives

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1

Hi,

Is there a systematic approach to preprocess .ml containing toplevel directives so that the preprocessed .ml output file can be compiled with ocaml compilers?
Toplevel directives like #directory would require some commandline arguments to be added to the ocaml compiler, but we are willing to take the complexity.

Thanks!

2

You didn’t say much about your use case so the following suggestion may be off.

Did you maybe consider doing the converse ?

That is augument your sources with directives as floating attributes e.g.

[@@@top.directory "my/dir"]

and extract the directives via compiler libs. These files will compile without surgery.

3

Hi,

The background is that we have a few big .ml files that contain top directives. They are supposed to be used with #use "x.ml";; in OCaml REPL, but as the ml files are getting larger, running #use is now taking a significant time (around a minute). To make loading it faster, I am looking for a method to compile x.ml into .cmo/.cmi/.cma and load it.

Does using the floating attribute generate new .ml files that can be compiled with ocamlopt or ocamlc, or am I understanding wrong?

4

if you don’t mind jiggling the compiler to ignore #-directives…

cd opam var ocaml-variants:build
vi parsing/lexer.mll
the compiler lexer has a clause for handling just # <line> "<file name>"
at

and directive = parse
...

add this 2nd case to ignore any other # directive:

  |  [^ '\010' '\013'] * { token lexbuf }

make ocamlc.opt ocamlopt.opt install

5

Custom attributes are ignored by the compiler. You can put there whatever you want.

You may also want to have a look at ocamlscript (or b0caml, but it’s unreleased and again one of these projects I had that was assuming we were going towards a simplification of the notion of library and needs to be reviewed now that this did not happen).

6

Hi all,
It turns out that the number of toplevel directives was pretty small so I could manually deal with them. :). Thanks for your all answers.

I have a new question though. The .ml file is using Topdirs and Toplevel modules, and when I compile the .ml using ocamlc I am seeing:

$ ocamlfind ocamlc -linkpkg x.ml -package compiler-libs
...
Error: Required module `Topdirs' is unavailable

Does anyone have idea about this error message?

7

Topdirs is in the compiler-libs.toplevel library.

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