What's missing to make D2 feature complete?

[via Digitalmars-d]

On Tuesday, 23 December 2014 at 08:43:06 UTC, ketmar via 
Digitalmars-d wrote:
> that's why we have `in` keyword, which clearly indicates that 
> argument
> is "in only". making `in` default is breaking of my lovely 
> principle of
> least astonishment.

"in" is "const scope"... But signatures in D are too noisy. It is 
very difficult to avoid, so it is important to keep signatures 
simple for increased legibility.

I think "in", "out", "inout" and "scope "should go. Make all 
parameters that are by-value immutable by default. Make all 
parameters that are ref scope restricted and alias free by 
default. Add tuples. Add ways to express that parameters are used 
in dangerous ways ("escapable", "returnable"...)