Commutativity prblem in @rule macro

[Bumblebee00]

julia> @syms a b c
(a, b, c)

julia> r = @rule ~a*~b + ~a*~c => ~a * (~b+~c)
~a * ~b + ~a * ~c => ~a * (~b + ~c)

julia> r(a*b + a*c)
a*(b + c)

julia> r(b*a + b*c)

julia> 

a way to fix could be generate the permutations of all commutative operations at the top level, and not during the recursion

[abraunst]

At least version v3.32.0 doesn't seem to have this problem:

(@v1.12) pkg> st SymbolicUtils
Status `~/.julia/environments/v1.12/Project.toml`
⌃ [d1185830] SymbolicUtils v3.32.0
I
julia> using SymbolicUtils

julia> r = @rule ~a*~b + ~a*~c => ~a * (~b+~c)
~a * ~b + ~a * ~c => ~a * (~b + ~c)

julia> @syms a::Real b::Real c::Real
(a, b, c)

julia> r(b*a + b*c)
(a + c)*b

julia> r(c*b + a*b)
(a + c)*b

julia> r(b*c + a*b)
(a + c)*b

julia> r(c*b + b*a)
(a + c)*b

[AayushSabharwal]

It does have this problem.

julia> r(b*a + b*c)
(a + c)*b

julia> r(c*b + a*b)
(a + c)*b

julia> r(b*c + a*b)
(a + c)*b

julia> r(c*b + b*a)

All of these expressions passed to r are stored in exactly the same way. In fact, they're the same object in memory. It just doesn't show up there because coincidentally the hashes of a, b and c are such that the rule explores the expression in a way that it matches.

[AayushSabharwal]

I've described the issue in this message on discourse.