D and Nim

[Vlad Levenfeld via Digitalmars-d]

On Monday, 5 January 2015 at 01:12:29 UTC, Brian Rogoff wrote:
> Nim's parametric polymorphism is less powerful than D's I think 
> (the words 'generic' and 'template' are used differently in the 
> two communities so I'll try and be extra clear) but Nim has a 
> powerful macro system and a (still unfinished) kind of "type 
> classes" which give it an edge on D.

Could you elaborate on the difference between D's 
templates/mixins and Nim's macros/type classes?