Improve 'simplify' function

[magistere]

No description provided.

[johnmyleswhite]

Very nice. Thanks!

[ivarne]

I tried to implement this functionality some months ago, and I think I remember that the multiplication was more complex because the parser translate multiplication to a chain of binary operations. I will check tomorrow.

[johnmyleswhite]

That may be true. But that shouldn't break this code, just make it superfluous, right?

[ivarne]

Hmm.. It looks like the issue I was having has been fixed. I tried to get some comments on my own attempt at fixing simplify! in #14 (comment), but apparently nobody noticed.

[magistere]

@ivarne I assume that something was changed in multiplication implementation in Julia core. Now I get

julia> simplify(:(*x))
ERROR: syntax: missing separator in tuple

So, the first special case in simplify(::SymbolParameter{:*}, args) should be modified or removed.

[ivarne]

That is just a syntax issue, you can still do :(*(x)) and get to the special case. It is pretty useless, but still a valid simplification.