Which language constructs could be done as a library if we accept some breaking changes?

[Ola Fosheim Grøstad]

If there was a majority in favour of D3, with breaking changes, 
and a strong focus on meta-programming, then it would make a lot 
of sense to streamline the language.

What would that consist of? I would say:

1. Figuring out what the missing bits for meta-programming are.

2. Taking out all language constructs that can be implemented as 
a library feature.

3. Add some syntactical sugar where necessary (mapping to library 
features).

Which features that are currently in the language could with some 
adjustments be done as a library feature?

Hashtable?

Dynamic array?

Slices?

Shared?

Class?

Others language features…?

(I think all these could be done if meta-programming facilities 
were strengthened.)

What do you think?