const?? When and why? This is ugly!

[Andrei Alexandrescu]

Walter Bright wrote:
> If I may restate your case, it is that given function that does 
> something with character arrays:
> 
> int foo(string s);
> 
> and you wish to pass a mutable character array to it. If foo was 
> declared as:
> 
> int foo(const(char)[] s);
> 
> then it would just work. So why is it declared immutable(char)[] when 
> that isn't actually necessary?
> 
> The answer is to encourage the use of immutable strings. I believe the 
> future of programming will tend towards ever more use of immutable data, 
> as immutable data:
> 
> 1. is implicitly sharable between threads

In fact const data is also implicitly sharable between threads. This is 
because shared is not implicitly convertible to const. No?

Andrei