MersenneTwister (#223)

* Nograd for MersenneTwister

* MersenneTwister frule

* Bumps patch version

* Bump patch version

Author: willtebbutt

Project.toml

@@ -1,10 +1,11 @@
 name = "ChainRules"
 uuid = "082447d4-558c-5d27-93f4-14fc19e9eca2"
-version = "0.7.3"
+version = "0.7.4"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
 Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"

src/ChainRules.jl

@@ -6,6 +6,7 @@ using Reexport
 using Base.Broadcast: materialize, materialize!, broadcasted, Broadcasted, broadcastable
 using LinearAlgebra
 using LinearAlgebra.BLAS
+using Random
 using Requires
 using Statistics
 
@@ -35,6 +36,8 @@ include("rulesets/LinearAlgebra/dense.jl")
 include("rulesets/LinearAlgebra/structured.jl")
 include("rulesets/LinearAlgebra/factorization.jl")
 
+include("rulesets/Random/random.jl")
+
 # Note: The following is only required because package authors sometimes do not
 # declare their own rules using `ChainRulesCore.jl`. For arguably good reasons.
 # So we define them here for them.

src/rulesets/Random/random.jl

@@ -0,0 +1,8 @@
+frule(Δargs, ::typeof(MersenneTwister), args...) = MersenneTwister(args...), Zero()
+
+function rrule(::typeof(MersenneTwister), args...)
+    function MersenneTwister_rrule(ΔΩ)
+        return (NO_FIELDS, map(_ -> Zero(), args)...)
+    end
+    return MersenneTwister(args...), MersenneTwister_rrule
+end

test/rulesets/Random/random.jl

@@ -0,0 +1,22 @@
+@testset "random" begin
+    @testset "MersenneTwister" begin
+        @testset "no args" begin
+            rng, dΩ = frule((5.0,), MersenneTwister)
+            @test rng isa MersenneTwister
+            @test dΩ isa Zero
+
+            rng, pb = rrule(MersenneTwister)
+            @test rng isa MersenneTwister
+            @test first(pb(10)) isa Zero
+        end
+        @testset "unary" begin
+            rng, dΩ = frule((5.0, 4.0), MersenneTwister, 123)
+            @test rng isa MersenneTwister
+            @test dΩ isa Zero
+
+            rng, pb = rrule(MersenneTwister, 123)
+            @test rng isa MersenneTwister
+            @test all(map(x -> x isa Zero, pb(10)))
+        end
+    end
+end

test/runtests.jl

@@ -41,6 +41,12 @@ println("Testing ChainRules.jl")
 
         print(" ")
 
+        @testset "Random" begin
+            include(joinpath("rulesets", "Random", "random.jl"))
+        end
+
+        print(" ")
+
         @testset "packages" begin
             include(joinpath("rulesets", "packages", "NaNMath.jl"))
             include(joinpath("rulesets", "packages", "SpecialFunctions.jl"))