Okay, I withdraw my argument that the Java strategy is better then
the ML strategy However, I'd like to use the following example
to make my point clear.
I want to combine two arrays into one. Here is the code in OCaml.
let combine_arrays a b =
let alen = Array.length a in
let blen = Array.length b in
let c = Array.make (alen + blen) ?
in begin
for i = 0 to alen - 1 do
c.(i) <- a.(i)
done;
for i = 0 to blen -1 do
c.(alen + i) <- b.(i)
done
end
Of course, you need to provide ? to make the above code work.
Here is my argument:
(1) If you try to provide ?, the code becomes repulsive.
(2) If you really want to make sure that 'c' is well-initialized,
you should probably check this after those two loops. The question
is how to incorporate the checking result into the type system.
(3) If you initialize 'c' with a (wrong) value, it seems to me
that nothing is achieved.
(4) Also, the problem cannot be solved using option type.
This is a precise senario that I had in mind, where the kind of
mandatory array initialization in ML-like langugages is simply
inappropriate, isn't it?
Cheers,
--Hongwei
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