Pure factory functions

[Andrei Alexandrescu via Digitalmars-d]

https://github.com/dlang/dlang.org/pull/1528 identifies the category 
"pure factory functions" - pure functions that can be assumed to create 
new mutable data, as of yet not referenced by any part in the program.

This has far-reaching consequences with regard to creating complex 
immutable data structures. Other idioms may also be affordable with this 
notion. Thought it might be a good topic to look into for the more 
theoretically-inclined of us such as Timon Gehr.


Andrei