Usage of compare with functionnal values

Hello,

I've found a difference between the functions compare and (=) with lazy 
values.

Image this definition :

let foo = Lazy.from_fun Random.bits;;
let bar = Lazy.from_fun Random.bits;;

Testing the equality raises an exeption :

foo = bar;;
Exception: Invalid_argument "equal: functional value".

Where comparaison returns 0 :

compare foo bar;;
- : int = 0

(of course, everithing becomes right once the values has been forced :

# foo = bar;;
- : bool = false
# compare foo bar;;
- : int = -1
)

The documentation says that comparing two functionnals values *may* 
raise an exception, but I'm surprised with the result in this case. Is 
that expected ?

Thanks for your answers

Sébastien Dailly