[q-lang-users] newbie question: Efficiency & other stuff

[Arnoldo J. M. M. <ar...@da...>]

Hello All,

I have this piece of code:

dmatch(E1,E2) = (#expand(E1) + #expand(E2)) - (2 * dmatchAux(expand
(E1),expand(E2)));

I have executed some stats commands after executing this rule, with and
without the "(#expand(E1) + #expand(E2))" and it seems that q is
calculating expand(E1) and expand(E2) 2 times (1). 

1) Is this true?

2) if that is so, is there a way of implementing a "let" so I can
compute only once the results of expand(_)? Of course I could create an
elaborate chain of rules and allow this, but is there a way that doesn't
involve creating several rules? 

Thank you!

--------------------------
(1) (expand(...) is a deterministic rule, it will always return the same
result for the same input)