const sucks

[Walter Bright]

Bill Baxter wrote:
> I think you mean "this option is being discussed *once again*".  It
> was discussed quite a lot before the current invariant/const was
> implemented.  The consensus was definitely that it was worth a shot.
> But it did not get a shot.

Yes, it was discussed a lot.

> I recall Walter's main argument against it was that local variable
> really shouldn't be const-by-default since you're usually creating
> them because you want to manipulate them.  But then you end up with a
> system where local variable declarations and parameter declarations
> follow very different rules.  "int[] foo" in one place means something
> different from "int[] foo" in the other place.  I'm not convinced this
> would be that confusing, though.  There could be other problems with
> const-by-default in parameters, but that one doesn't seem like such a
> big deal.

The problem is things like:

   void foo(int[] a)
   {
     int[] b;
   }

so a is const, and b is mutable? That's very confusing. It gives the 
appearance of D having a lot of wacky and arbitrary semantic rules.