Wouldn't it anyway be better to advise to add something like: 

```
(add-to-list 'load-path
 (concat 
   (replace-regexp-in-string "\n$" ""
     (shell-command-to-string "opam config var share")) "/tuareg"))
```

Switches tend to come and go. So it's the kind of thing you should install in all your switches no ?