Thomas Fischbacher <Thomas.Fischbacher@Physik.Uni-Muenchen.DE> writes:

   Actually, this brings me to a question I wanted to ask for a long time: 
   while I never used this so far, I just assumed that OCaml does provide 
   hash tables where keys are compared w.r.t. "being the same" ('==' , that 
   is), rather than only hash tables where keys are compared for "being 
   equal" (say, '=').
   
Just look at hash.ml:

    let find h key =
      match h.data.((hash key) mod (Array.length h.data)) with
        Empty -> raise Not_found
      | Cons(k1, d1, rest1) ->
          if compare key k1 = 0 then d1 else
             ^^^^^^^^^^^^^^^^^^

So it's structual equality, which is the same as '=' modulo the
float nan issue.

Bye,

Hendrik