Rules infrastructure wishlist about symbolicutils.jl HOT 4 CLOSED

Another thing I think we should support is nested rule application. e.g.

@rule(sin(+(~~x)) 
      => sin(@acrule(~y::multiple_of(2π) 
                     => zero(~y))(+(~~x...))))

This basically says that there is a rule (you can drop multiples of 2π from sums) which only applies inside the body of a trig function. Currently this is an error:

julia> @rule sin(+(~~x)) => sin(@acrule(~y::multiple_of(2π) => zero(~y))(+(~~x...)))
ERROR: LoadError: syntax: invalid syntax (escape (outerref @acrule))
Stacktrace:
 [1] top-level scope at REPL[13]:1
in expression starting at <macrocall>:0

from symbolicutils.jl.

Interesting case! Seems like it's only needed because + is ac but sin is not... otherwise you could write @acrule sin(+(~y::multiple_of(pi), ...etc...)).

from symbolicutils.jl.

Okay, turns out this works if you just separate out the rules:

using SymbolicUtils
@vars x y a::Integer
r = let
    r_inner = RuleSet([@acrule ~y::multiple_of(2π) => zero(~y)])
    @rule sin(+(~~x)) => sin(r_inner(+(~~x...)))
end

julia> r(sin(x + 2π*a + y))
(sin(x + y))

from symbolicutils.jl.

I'm closing this because I think we have the most important items here, let's open new issues as need arises.

The Segment optimizations are not very useful anymore since we do most of those complex rules using @acrule.

from symbolicutils.jl.