feat: allow type-casting numbers to tracednumbers (#209)

* feat: allow type-casting numbers to tracednumbers

* chore: apply formatting suggestion

Author: avik-pal

src/TracedRNumber.jl

@@ -52,6 +52,11 @@ function Base.convert(::Type{TracedRNumber{T}}, x::Number) where {T}
     return promote_to(TracedRNumber{T}, x)
 end
 
+TracedRNumber{T}(x::TracedRNumber{T}) where {T} = x
+function TracedRNumber{T}(x::Number) where {T}
+    return promote_to(TracedRNumber{T}, x)
+end
+
 function promote_to(::Type{TracedRNumber{T}}, rhs) where {T}
     if isa(rhs, TracedRNumber)
         rhs isa TracedRNumber{T} && return rhs

test/basic.jl

@@ -488,3 +488,13 @@ end
         @test res3 isa ConcreteRArray
     end
 end
+
+relu(x::T) where {T<:Number} = max(T(0), x)
+relu(x) = relu.(x)
+
+@testset "type casting" begin
+    x = randn(2, 10)
+    x_ra = Reactant.to_rarray(x)
+
+    @test @jit(relu(x_ra)) ≈ relu(x)
+end