Re: Combining mutable objects with const references

anonposting@[EMAIL PROTECTED]
 writes:
> But an imperative programmer is never forced to destructively update.
> He can make a new object with the normal constructor, or make a copy
> of another object using a copy constructor (i.e. a funcion which makes
> a new object identical to an existing one).

In principle that is true; in practice, functional language systems
tend to provide special data structures that allow programming in a
non-mutating style while minimizing copying.  E.g. functional
programmers will typically implement lookup tables with self-balancing
trees rather than hash tables, so you can do an "update" in O(log n)
operations (sharing all nodes other than the path to the root from the
node you changed) instead of the O(n) that it would take to copy the
whole structure.  Chris Okasaki's book "Purely Functional Data
Structures" covers the subject in depth.