Larry Evans wrote:
On 03/18/08 10:30, Eric Niebler wrote:
These are domain-specific use cases. The code for that belongs in your DSEL, not in Proto.
OK. But so is:
-x + x -> 0
0 + x -> x
domain specific, which is what Markus was asking for.
Right, Markus was just looking for some examples. He didn't want me to put those transforms in Proto.
Now I could just translate:
Empty( A | B ) -> Empty<A> * Empty<B> Empty(grammar_terminal) -> 1 Empty(epsilon) -> 0
and I've got what I want and it's in the domain Markus was talking about. So, if you do it for the arith domain (Markus'), then you'd have to have a set of "simplification rule" for that domain. Replace the simplification rules for arith domain with simplification rules for domain X, where X is boolean expressions or grammar expressions or some other domain, and you've generalized what you can simplify.
My point was that If you can do it for Markus' domain, then you can to it for domain X. IOW, provide a set of simplification rules for a particular domain.
Maybe the next version? ;)
It still doesn't belong in Proto. I see it as analogous to custom grammars and Spirit. Just because someone has written a useful grammar doesn't mean that Joel should make it part of Spirit. Instead, there is a separate Spirit app repository for these bits of useful Spirit code. Maybe there should be a Proto app repository, or maybe you and Markus can write the expression reduction transform and I can put it in libs/proto/example. -- Eric Niebler Boost Consulting www.boost-consulting.com