ParserCobinator like scala in D

[bearophile]

> Template Library: http://ideone.com/3rKF4
> ParserCombinator: http://ideone.com/YlGP2
> PEGParser: http://ideone.com/vkTyh
> Sample(Expression of four arithmetic operations): http://ideone.com/0uc3t
> 
> What do you think about this?

The code looks clean enough.
I suggest to use 4 spaces as indent (or a single tab).
You may rewrite tuple.field[1] as tuple[1]
An  alias char[] str;  may shorten some signatures a bit.

See also Pymeta, an implementation of OMeta:
http://washort.twistedmatrix.com/

Bye,
bearophile