@associative and @commutative properties for functions

[bearophile]

Ilya Yaroshenko:

> Rationale:
> More CTFE magic with UFCS and operator overlaoding.
>
> Related links:
> http://forum.dlang.org/thread/ibhug0$3065$1@digitalmars.com?page=2#post-ibjt80:2418oc:241:40digitalmars.com

@associative and @commutative are useful and quite nice, but the 
D compiler is not smart enough to verify that a function has 
those properties. In general the D design tries to avoid 
unverifiable attributes. C++ programmers will probably have a way 
to express (unverified) properties like @associative using a new 
syntax (this page is not very updated):

http://en.wikipedia.org/wiki/Concepts_%28C%2B%2B%29#Axioms

Bye,
bearophile