Make Symbolics work with Rational numbers

Author: adamslc

src/SymbolicUtils.jl

@@ -7,7 +7,7 @@ export @syms, term, showraw, hasmetadata, getmetadata, setmetadata
 using DataStructures
 using Setfield
 import Setfield: PropertyLens
-import Base: +, -, *, /, \, ^, ImmutableDict
+import Base: +, -, *, /, //, \, ^, ImmutableDict
 using ConstructionBase
 include("types.jl")
 

src/types.jl

@@ -781,6 +781,10 @@ mul_t(a) = promote_symtype(*, symtype(a))
 
 /(a::SN, b::Number) = inv(b) * a
 
+//(a::Union{SN, Number}, b::SN) = a / b
+
+//(a::SN, b::T) where {T <: Number} = (one(T) // b) * a
+
 """
     Pow(base, exp)
 

test/basics.jl

@@ -112,6 +112,11 @@ end
     @test SymbolicUtils.promote_symtype(ifelse, Bool, Int, Bool) == Union{Int, Bool}
     @test_throws MethodError w < 0
     @test isequal(w == 0, Term{Bool}(==, [w, 0]))
+
+    @eqtest x // 5 == (1 // 5) * x
+    @eqtest x // Int16(5) == Rational{Int16}(1, 5) * x
+    @eqtest 5 // x == 5 / x
+    @eqtest x // a == x / a
 end
 
 @testset "err test" begin