How to require a module in jane street Ocaml

Question

I'm working through http://dev.realworldocaml.org/records.html and am having a problem with require

#require "re.posix";;

(* open Base ;;
open Core ;; *)

(* type <record-name> =
  {
    <field>: <type>;
    <field>: <type>;
  } *)

  type service_info =
    {
      service_name : string ;
      port : int ;
      protocol : string ;
    }
;;

(* #require "re.postix";; *)

let service_info_of_string line =
  let matches =
    Re.exec (Re.Posix.compile_pat "([a-zA-Z]+)[\t]+([0-9]+)/([a-zA-Z]+)") line
  in
  {
    service_name = Re.get matches 1;
    port = Int.of_string (Re.get matches 2);
    protocol = Re.get matches 3;
  }
;;

print_endline "foobar"

This is the output from me calling dune build

dune build hello_world.exe 
         ppx hello_world.pp.ml (exit 1)
(cd _build/default && .ppx/jbuild/ppx_jane/ppx.exe -o hello_world.pp.ml --impl hello_world.ml --dump-ast)
File "hello_world.ml", line 385, characters 0-1:
Error: Syntax error

Here is the jbuild

(executable
 ((name hello_world)
 (libraries (core))
 (preprocess (pps (ppx_jane)))))

I found that "#use "topfind" works if I compile with ocamlc. But havent been able to make it work with dune.

Tips appreciated.thanks

it works on my side, provided that you add "re" in the libraries statement, remove the #require stmt, and uncomment 'open Core'. — Pierre G., Oct 23 '18 at 16:56

score 0 · Answer 1 · answered Oct 24 '18 at 09:20

The following fixes shall make your example works :

open Core ;; (* in particular, it makes Int visible *)


type service_info =
    {
      service_name : string ;
      port : int ;
      protocol : string ;
    }
;;

(* #require "re.postix";; *)

let service_info_of_string line =
  let matches =
    Re.exec (Re.Posix.compile_pat "([a-zA-Z]+)[\t]+([0-9]+)/([a-zA-Z]+)") line
  in
  {
    service_name = Re.get matches 1;
    port = Int.of_string (Re.get matches 2);
    protocol = Re.get matches 3;
  }
;;

print_endline "foobar"

And jbuild :

(executable
 ((name hello_world)
 (libraries (core re))
 (preprocess (pps (ppx_jane)))))

How to require a module in jane street Ocaml

1 Answers1