How to prevent OCaml batteries from overriding values

The package Batteries.Num overrides the functions (+), (-), ... So the compiler gives an error on the following simple code

open Batteries
open Num
let a = 4 + 4;;

File "", line 3, characters 8-9: Error: This expression has type int but an expression was expected of type Batteries.Num.num = Num.num

I compile with "ocamlfind ocamlc -package batteries".

EDIT: I know I could use Pervasives.(+) or just open Num locally.

But I am able to compile this program successfully with ocamlbuild with the simplest _tags file: <*>: pkg_batteries, package(batteries), package(num)

Where is the magic? How can I compile like ocamlbuild does with a Makefile?

EDIT: I found the solution. I actually had two versions of batteries (1.4 and 2.2), and ocamlfind gave the version 2.2 on command line, and 1.4 on ocamlbuild. I don't know why. I believe the early version of batteries didn't redefine the module Num (but you had to use BatNum), so the problem doesn't occur with the older version. Thanks for the answers.


What command are you using the build it? Because if you aren't specifying a build target (i.e. your command is ocamlbuild instead of ocamlbuild a.native) it will appear as though its compiling even though it isn't.

What is ACTUALLY happening when you try "ocamlfind ocamlc -package batteries" is that the + from nums is overshadowing the + from Pervasives.

You could do let a = Pervasives.(+) 4 4;;, or instead of opening Nums, do Nums. for everything like that.

You can just refer to the function by using the module name you want.

If you want the (+) from Pervasives, you just say Pervasives.(+) x y instead of x + y.

The solution I have used when I faced this problem is to open Pervasive to override Batteries values.

open Batteries
open Num
open Pervasives

let a = 4 + 4;;

Need Your Help

Dynamic JavaScript returned by webapi


I am using requirejs to load JavaScript for my page. I have a webApi route that dynamically reads from a file and returns JSON using the Newtonsoft JObject. On the client side I then take the res...

Cron Job Commands not working

cron crontab

I am new to cron jobs and have set up one in Plesk to execute every minute however I am not sure if the command is correct due to it not working.

About UNIX Resources Network

Original, collect and organize Developers related documents, information and materials, contains jQuery, Html, CSS, MySQL, .NET, ASP.NET, SQL, objective-c, iPhone, Ruby on Rails, C, SQL Server, Ruby, Arrays, Regex, ASP.NET MVC, WPF, XML, Ajax, DataBase, and so on.