Minor fixes:

src/layers/normalise.jl

@@ -1,6 +1,6 @@
 """
-    testmode!(m, val=true)
-
+    testmode!(m)
+    testmode!(m, false)
 Put layers like [`Dropout`](@ref) and [`BatchNorm`](@ref) into testing mode
 (or back to training mode with `false`).
 """
@@ -13,11 +13,9 @@ _testmode!(m, test) = nothing
 
 """
     Dropout(p)
-
 A Dropout layer. For each input, either sets that input to `0` (with probability
 `p`) or scales it by `1/(1-p)`. This is used as a regularisation, i.e. it
 reduces overfitting during training.
-
 Does nothing to the input once in [`testmode!`](@ref).
 """
 mutable struct Dropout{F}
@@ -43,9 +41,7 @@ end
 _testmode!(a::Dropout, test) = (a.active = !test)
 
 """
-
     LayerNorm(h::Integer)
-
 A [normalisation layer](https://arxiv.org/pdf/1607.06450.pdf) designed to be
 used with recurrent hidden states of size `h`. Normalises the mean/stddev of
 each input before applying a per-neuron gain/bias.
@@ -69,23 +65,17 @@ end
     BatchNorm(channels::Integer, σ = identity;
               initβ = zeros, initγ = ones,
               ϵ = 1e-8, momentum = .1)
-
 Batch Normalization layer. The `channels` input should be the size of the
 channel dimension in your data (see below).
-
 Given an array with `N` dimensions, call the `N-1`th the channel dimension. (For
 a batch of feature vectors this is just the data dimension, for `WHCN` images
 it's the usual channel dimension.)
-
 `BatchNorm` computes the mean and variance for each each `W×H×1×N` slice and
 shifts them to have a new mean and variance (corresponding to the learnable,
 per-channel `bias` and `scale` parameters).
-
 See [Batch Normalization: Accelerating Deep Network Training by Reducing
 Internal Covariate Shift](https://arxiv.org/pdf/1502.03167.pdf).
-
 Example:
-
 ```julia
 m = Chain(
   Dense(28^2, 64),
@@ -93,32 +83,23 @@ m = Chain(
   Dense(64, 10),
   BatchNorm(10),
   softmax)
-
-y = m(rand(28^2, 10))
 ```
-
-To use the layer at test time set [`testmode!(m, true)`](@ref).
 """
-mutable struct BatchNorm
-  λ  # activation function
-  β  # bias
-  γ  # scale
-  μ  # moving mean
-  σ²  # moving var
-  ϵ
-  momentum
+mutable struct BatchNorm{F,V,W,N}
+  λ::F  # activation function
+  β::V  # bias
+  γ::V  # scale
+  μ::W  # moving mean
+  σ²::W  # moving std
+  ϵ::N
+  momentum::N
   active::Bool
 end
 
-# NOTE: Keeping the ϵ smaller than 1e-5 is not supported by CUDNN
-function BatchNorm(chs::Integer, λ = identity;
-          initβ = (i) -> zeros(i),
-          initγ = (i) -> ones(i),
-          ϵ = 1f-5,
-          momentum = 0.1)
+BatchNorm(chs::Integer, λ = identity;
+          initβ = (i) -> zeros(i), initγ = (i) -> ones(i), ϵ = 1e-5, momentum = .1) =
   BatchNorm(λ, param(initβ(chs)), param(initγ(chs)),
-            zeros(Float32, chs), ones(Float32, chs), ϵ, momentum, true)
-end
+            zeros(chs), ones(chs), ϵ, momentum, true)
 
 function (BN::BatchNorm)(x)
   size(x, ndims(x)-1) == length(BN.β) ||
@@ -132,7 +113,7 @@ function (BN::BatchNorm)(x)
 
   if !BN.active
     μ = reshape(BN.μ, affine_shape...)
-    σ = reshape(BN.σ, affine_shape...)
+    σ² = reshape(BN.σ², affine_shape...)
   else
     T = eltype(x)
 
@@ -143,8 +124,8 @@ function (BN::BatchNorm)(x)
 
     # update moving mean/std
     mtm = data(convert(T, BN.momentum))
-    BN.μ = (1 - mtm) .* BN.μ .+ mtm .* dropdims(data(μ), dims = (axes...,))
-    BN.σ² = ((1 - mtm) .* BN.σ² .+ mtm .* dropdims(data(σ²), dims = (axes...)) .* m ./ (m - 1))
+    BN.μ = (1 - mtm) .* BN.μ .+ mtm .* dropdims(data(μ), dims = axes)
+    BN.σ² = ((1 - mtm) .* BN.σ² .+ mtm .* dropdims(data(σ²), dims = axes) .* m ./ (m - 1))
   end
 
   let λ = BN.λ
@@ -152,7 +133,11 @@ function (BN::BatchNorm)(x)
   end
 end
 
-@treelike BatchNorm
+children(BN::BatchNorm) =
+  (BN.λ, BN.β, BN.γ, BN.μ, BN.σ, BN.ϵ, BN.momentum, BN.active)
+
+mapchildren(f, BN::BatchNorm) =  # e.g. mapchildren(cu, BN)
+  BatchNorm(BN.λ, f(BN.β), f(BN.γ), f(BN.μ), f(BN.σ), BN.ϵ, BN.momentum, BN.active)
 
 _testmode!(BN::BatchNorm, test) = (BN.active = !test)