Split core out into AbstractChainRules,

Requires-ize 3rd party packages.
Reorganize all files

Author: oxinabox

Project.toml

@@ -1,23 +1,25 @@
 name = "ChainRules"
 uuid = "082447d4-558c-5d27-93f4-14fc19e9eca2"
-version = "0.0.1"
+version = "0.1.0"
 
 [deps]
-Cassette = "7057c7e9-c182-5462-911a-8362d720325c"
+AbstractChainRules = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
-NaNMath = "77ba4419-2d1f-58cd-9bb1-8ffee604a2e3"
-SpecialFunctions = "276daf66-3868-5448-9aa4-cd146d93841b"
+Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
+Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
 [compat]
-Cassette = "^0.2"
 FDM = "^0.6"
 julia = "^1.0"
+AbstractChainRules = "^0.1"
 
 [extras]
 FDM = "e25cca7e-83ef-51fa-be6c-dfe2a3123128"
+NaNMath = "77ba4419-2d1f-58cd-9bb1-8ffee604a2e3"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
+SpecialFunctions = "276daf66-3868-5448-9aa4-cd146d93841b"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["FDM", "Random", "Test"]
+test = ["FDM", "Random", "Test", "SpecialFunctions", "NaNMath"]

REQUIRE

@@ -1,8 +1,17 @@
 module ChainRules
+using Reexport
+@reexport using AbstractChainRules
+# basically everything this package does is overloading these
+import AbstractChainRules: rrule, frule
+
+# deal with name clashes
+const accumulate = AbstractChainRules.accumulate
+const accumulate! = AbstractChainRules.accumulate!
+
 
-using Cassette
 using LinearAlgebra
 using LinearAlgebra.BLAS
+using Requires
 using Statistics
 using Base.Broadcast: materialize, materialize!, broadcasted, Broadcasted, broadcastable
 
@@ -13,22 +22,32 @@ if VERSION < v"1.3.0-DEV.142"
     import LinearAlgebra: dot
 end
 
-import NaNMath, SpecialFunctions
-
-export AbstractRule, Rule, frule, rrule
-
-include("differentials.jl")
-include("rules.jl")
-include("rules/base.jl")
-include("rules/array.jl")
-include("rules/broadcast.jl")
-include("rules/mapreduce.jl")
-include("rules/linalg/utils.jl")
-include("rules/linalg/blas.jl")
-include("rules/linalg/dense.jl")
-include("rules/linalg/structured.jl")
-include("rules/linalg/factorization.jl")
-include("rules/nanmath.jl")
-include("rules/specialfunctions.jl")
+include("helper_functions.jl")
+
+include("rulesets/Base/base.jl")
+include("rulesets/Base/array.jl")
+include("rulesets/Base/broadcast.jl")
+include("rulesets/Base/mapreduce.jl")
+
+include("rulesets/LinearAlgebra/utils.jl")
+include("rulesets/LinearAlgebra/blas.jl")
+include("rulesets/LinearAlgebra/dense.jl")
+include("rulesets/LinearAlgebra/structured.jl")
+include("rulesets/LinearAlgebra/factorization.jl")
+
+# Note: The following is only required because package authors do not use
+# declare their own rules using AbstractChainRules. For arguably good reasons.
+# so we define them here for them.
+function __init__()
+    @require NaNMath="77ba4419-2d1f-58cd-9bb1-8ffee604a2e3" begin
+        include("rulesets/packages/NaNMath.jl")
+        using .NaNMathGlue
+    end
+
+    @require SpecialFunctions="276daf66-3868-5448-9aa4-cd146d93841b" begin
+        include("rulesets/packages/SpecialFunctions.jl")
+        using .SpecialFunctionGlue
+    end
+end
 
 end # module