diff --git a/src/Flux.jl b/src/Flux.jl
index 44864589..fdcd6194 100644
--- a/src/Flux.jl
+++ b/src/Flux.jl
@@ -19,11 +19,7 @@ include("params.jl")
 include("compiler/Compiler.jl")
 using .Compiler: @net
 
-include("layers/chain.jl")
-include("layers/affine.jl")
-include("layers/activation.jl")
-include("layers/cost.jl")
-
-include("data.jl")
+include("layers/stateless.jl")
+include("layers/basic.jl")
 
 end # module
diff --git a/src/data.jl b/src/data.jl
deleted file mode 100644
index a50be7a4..00000000
--- a/src/data.jl
+++ /dev/null
@@ -1,23 +0,0 @@
-"""
-    onehot('b', ['a', 'b', 'c', 'd']) => [false, true, false, false]
-
-    onehot(Float32, 'c', ['a', 'b', 'c', 'd']) => [0., 0., 1., 0.]
-
-Produce a one-hot-encoded version of an item, given a list of possible values
-for the item.
-"""
-onehot(T::Type, label, labels) = T[i == label for i in labels]
-onehot(label, labels) = onehot(Int, label, labels)
-
-"""
-    onecold([0.0, 1.0, 0.0, ...],
-            ['a', 'b', 'c', ...]) => 'b'
-
-The inverse of `onehot`; takes an output prediction vector and a list of
-possible values, and produces the appropriate value.
-"""
-onecold(y::AbstractVector, labels = 1:length(y)) =
-  labels[findfirst(y, maximum(y))]
-
-onecold(y::AbstractMatrix, l...) =
-  squeeze(mapslices(y -> onecold(y, l...), y, 2), 2)
diff --git a/src/layers/activation.jl b/src/layers/activation.jl
deleted file mode 100644
index 5b1a27e2..00000000
--- a/src/layers/activation.jl
+++ /dev/null
@@ -1,11 +0,0 @@
-# Sigmoid
-σ(x) = 1 ./ (1 + exp.(-x))
-# back!(::typeof(σ), Δ, x) = Δ .* σ(x).*(1.-σ(x))
-
-# Rectified Linear Unit
-relu(x) = max(0, x)
-# back!(::typeof(relu), Δ, x) = Δ .* (x .> 0)
-
-softmax(xs) = exp.(xs) ./ sum(exp.(xs), 2)
-
-flatten(xs) = reshape(xs, size(xs, 1), :)
diff --git a/src/layers/affine.jl b/src/layers/affine.jl
deleted file mode 100644
index e7cc862c..00000000
--- a/src/layers/affine.jl
+++ /dev/null
@@ -1,8 +0,0 @@
-@net type Affine
-  W
-  b
-  x -> x*W .+ b
-end
-
-Affine(in::Integer, out::Integer; init = initn) =
-  Affine(init(in, out), init(1, out))
diff --git a/src/layers/chain.jl b/src/layers/basic.jl
similarity index 68%
rename from src/layers/chain.jl
rename to src/layers/basic.jl
index 0003812c..a866cf4c 100644
--- a/src/layers/chain.jl
+++ b/src/layers/basic.jl
@@ -1,3 +1,5 @@
+# Chain
+
 type Chain
   layers::Vector{Any}
   Chain(xs...) = new([xs...])
@@ -12,3 +14,16 @@ Compiler.graph(s::Chain) =
   foldl((v, m) -> vertex(m, v), constant(inputnode(1)), s.layers)
 
 Base.getindex(c::Chain, i::AbstractArray) = Chain(c.layers[i]...)
+
+# Affine
+
+struct Affine{S,T}
+  W::S
+  b::T
+end
+
+Affine(in::Integer, out::Integer; init = initn) =
+  Affine(track(init(out, in)),
+         track(init(out)))
+
+(a::Affine)(x) = a.W*x .+ a.b
diff --git a/src/layers/cost.jl b/src/layers/cost.jl
deleted file mode 100644
index 99c9381a..00000000
--- a/src/layers/cost.jl
+++ /dev/null
@@ -1,7 +0,0 @@
-mse(ŷ, y) = sumabs2(ŷ .- y)/2
-
-# back!(::typeof(mse), Δ, ŷ, y) = Δ .* (ŷ .- y)
-
-logloss(ŷ, y) = -sum(y .* log.(ŷ))
-
-# back!(::typeof(logloss), Δ, ŷ, y) = 0 .- Δ .* y ./ ŷ
diff --git a/src/layers/stateless.jl b/src/layers/stateless.jl
new file mode 100644
index 00000000..ed871793
--- /dev/null
+++ b/src/layers/stateless.jl
@@ -0,0 +1,17 @@
+# Activation Functions
+
+σ(x) = 1 ./ (1 + exp.(-x))
+# back!(::typeof(σ), Δ, x) = Δ .* σ(x).*(1.-σ(x))
+
+relu(x) = max(0, x)
+# back!(::typeof(relu), Δ, x) = Δ .* (x .> 0)
+
+softmax(xs) = exp.(xs) ./ sum(exp.(xs), 2)
+
+# Cost functions
+
+mse(ŷ, y) = sumabs2(ŷ .- y)/2
+# back!(::typeof(mse), Δ, ŷ, y) = Δ .* (ŷ .- y)
+
+logloss(ŷ, y) = -sum(y .* log.(ŷ))
+# back!(::typeof(logloss), Δ, ŷ, y) = 0 .- Δ .* y ./ ŷ
diff --git a/src/utils.jl b/src/utils.jl
index 958d04e4..e2a4a050 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -1,5 +1,3 @@
-call(f, xs...) = f(xs...)
-
 # Arrays
 
 initn(dims...) = randn(dims...)/100
@@ -10,8 +8,31 @@ squeeze(xs, dim = 1) = Base.squeeze(xs, dim)
 stack(xs, dim = 1) = cat(dim, unsqueeze.(xs, dim)...)
 unstack(xs, dim = 1) = [slicedim(xs, dim, i) for i = 1:size(xs, dim)]
 
-convertel(T::Type, xs::AbstractArray) = convert.(T, xs)
-convertel{T}(::Type{T}, xs::AbstractArray{T}) = xs
+"""
+    onehot('b', ['a', 'b', 'c', 'd']) => [false, true, false, false]
+
+    onehot(Float32, 'c', ['a', 'b', 'c', 'd']) => [0., 0., 1., 0.]
+
+Produce a one-hot-encoded version of an item, given a list of possible values
+for the item.
+"""
+onehot(T::Type, label, labels) = T[i == label for i in labels]
+onehot(label, labels) = onehot(Int, label, labels)
+
+"""
+    onecold([0.0, 1.0, 0.0, ...],
+            ['a', 'b', 'c', ...]) => 'b'
+
+The inverse of `onehot`; takes an output prediction vector and a list of
+possible values, and produces the appropriate value.
+"""
+onecold(y::AbstractVector, labels = 1:length(y)) =
+  labels[findfirst(y, maximum(y))]
+
+onecold(y::AbstractMatrix, l...) =
+  squeeze(mapslices(y -> onecold(y, l...), y, 2), 2)
+
+flatten(xs) = reshape(xs, size(xs, 1), :)
 
 a ∘ b = a .* b