> If you like using the mutable state, (...)

Now, I feel guilty to have used a Ref :-)

One Ref for ~5000 lines of code, it's not so bad to me :-)

(To be honnest, there are 8 Refs but 7 are used in order to emulate
the Thread.kill function)

> perhaps you might find the
> following code helpful. The key idea is packaging the clone function
> along with the arrow. There is no longer any need in any unsafe
> features. The lesson from our tagless final APLAS paper is that many
> things are significantly easier if we do the work at the production
> site rather than at the consumption site.
>
> (* The first component is the arrow itself, the second one is the clone
>    function*)
> type ('a,'b) arrow = {arrow: 'a -> 'b; clone: unit -> ('a,'b) arrow};;

I see... It's disappointing of simplicity...

Thanks !

-- 
Pierre-Evariste DAGAND