I've always wondered why O'Caml has no notion of immutable arrays or
vectors.  (Mutable) Arrays are often inconvenient because callers and
callees must negotiate who is doing the copying.  A conservative
approach will do too many copies.

Semantically, a vector of size n would be a record with
labels 0,...,n-1 and with O(1) access.  One would initialize them from
a constant (e.g. let v = [{ 42; 137; 1789 }]), a list, an array, or a
function. Updates would be requested by [{ v with 2 = 2000 }] and most
of the Array and List library is useful for vectors.

I admit that this is theoretically not very exciting (except for the
question when the `with' must copy and when not), but rather useful.

Cheers,
-Thorsten
-- 
Thorsten Ohl, Physics Department, TU Darmstadt -- ohl@hep.tu-darmstadt.de
http://heplix.ikp.physik.tu-darmstadt.de/~ohl/ [<=== PGP public key here]