[pure-lang-users] Swapping Symbols and Integers

[David B. <dh...@gm...>]

Hi,

I'm new to Q/Pure, and I've searched the archives a little and the "Q
in a Nutshell" doc a lot, but maybe I missed something.  I have been
just using Q up until now (because I only just found out about Pure).
I would like rewrite an expression like:

    4 * a * 3

to this:

    12 * a

So, I thought maybe I could create a rule like this:

    A:Symbol * B:Integer = B * A;
    // and maybe some more rules for associativity/commutivity

but, like I guessed, I get an undeclared type error for Symbol and
Integer (I think the type guards have to be algebraic types, not
simple expressions).  Is there a way to achieve this in Q or Pure?

Thanks,
-David