I don't know about syntax, but D sure needs first-class support
of tail immutability.
Take this code for example:
---
immutable class C
{
void foo()
{
//
}
}
void main()
{
auto c = new C();
c.foo();
}
---
Compile it and get
Error: immutable method C.foo is not callable using a mutable
object
Why? Because foo() is immutable and demands an immutable this
reference. The C instance c is only tail immutable, which
doesn't really count for anything. (So, "new C()" instead of
"new immutable(C)()" is legal but pretty much unusable, it seems.)
But why should *any* function require an immutable reference, as
opposed to a tail immutable reference? (Similarly for shared vs
tail shared.)
