Support more non-perturbable types

Project.toml

@@ -1,6 +1,6 @@
 name = "FiniteDifferences"
 uuid = "26cc04aa-876d-5657-8c51-4c34ba976000"
-version = "0.12.24"
+version = "0.12.25"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/to_vec.jl

@@ -20,6 +20,7 @@ end
 
 # Base case -- if x is already a Vector{<:Real} there's no conversion necessary.
 to_vec(x::Vector{<:Real}) = (x, identity)
+to_vec(x::Vector{<:Bool}) = invoke(to_vec, Tuple{DenseVector}, x)  # not for bool arrays
 
 # get around the constructors and make the type directly
 # Note this is moderately evil accessing julia's internals
@@ -260,7 +261,7 @@ function to_vec(d::Dict)
 end
 
 # non-perturbable types
-for T in (:DataType, :CartesianIndex, :AbstractZero)
+for T in (:DataType, :CartesianIndex, :AbstractZero, :Bool, :Nothing, :AbstractString, :Symbol)
     T_from_vec = Symbol(T, :_from_vec)
     @eval function FiniteDifferences.to_vec(x::$T)
         function $T_from_vec(x_vec::Vector)

test/to_vec.jl

@@ -200,16 +200,32 @@ end
         end
     end
 
-    @testset "DataType" begin
-        test_to_vec(Float64; check_inferred=false) # isa DataType
-        test_to_vec(Vector; check_inferred=false) # isa UnionAll
-    end
+    @testset "Nondifferentiable types" begin
+        @testset "DataType" begin
+            test_to_vec(Float64; check_inferred=false) # isa DataType
+            test_to_vec(Vector; check_inferred=false) # isa UnionAll
+        end
+
+        @testset "CartesianIndex" begin
+            test_to_vec(CartesianIndex(1))
+            test_to_vec(CartesianIndex(1, 2))
+            @test to_vec(CartesianIndex(1))[1] == []
+            @test to_vec(CartesianIndex(1, 3))[1] == []
+        end
+
+        @testset "Bool" begin
+            test_to_vec(true)
+            @test to_vec(true)[1] == []
 
-    @testset "CartesianIndex" begin
-        test_to_vec(CartesianIndex(1))
-        test_to_vec(CartesianIndex(1, 2))
-        @test to_vec(CartesianIndex(1))[1] == []
-        @test to_vec(CartesianIndex(1, 3))[1] == []
+            test_to_vec([true, false])
+            @test to_vec([true, false])[1] == []
+        end
+
+        @testset "misc Base types" begin
+            test_to_vec(nothing)
+            test_to_vec("a")
+            test_to_vec(:b)
+        end
     end
 
     @testset "ChainRulesCore Differentials" begin
@@ -260,8 +276,12 @@ end
     end
 
     @testset "fallback" begin
+        test_to_vec(ThreeFields(nothing, 1.5, false), check_inferred=false)
+        @test to_vec(ThreeFields(nothing, 1.5, false))[1] == [1.5]  # drops the two nonpertubable fields
+
         nested = Nested(ThreeFields(1.0, 2.0, "Three"), Singleton())
         test_to_vec(nested; check_inferred=false) # map
+
     end
 
     @testset "WrapperArray" begin