Check for nothing in update step

src/layers/recurrent.jl

@@ -69,7 +69,7 @@ end
 RNNCell(in::Integer, out::Integer, σ = tanh;
         init = glorot_uniform) =
   RNNCell(σ, init(out, in), init(out, out),
-          init(out), fill(Float32(0), out))
+          init(out), zeros(out))
 
 function (m::RNNCell)(h, x)
   σ, Wi, Wh, b = m.σ, m.Wi, m.Wh, m.b
@@ -108,7 +108,7 @@ end
 function LSTMCell(in::Integer, out::Integer;
                   init = glorot_uniform)
   cell = LSTMCell(init(out * 4, in), init(out * 4, out), init(out * 4),
-                  fill(Float32(0), out), fill(Float32(0), out))
+                  zeros(out), zeros(out))
   cell.b[gate(out, 2)] .= 1
   return cell
 end
@@ -154,7 +154,7 @@ end
 
 GRUCell(in, out; init = glorot_uniform) =
   GRUCell(init(out * 3, in), init(out * 3, out),
-          init(out * 3), fill(Float32(0), out))
+          init(out * 3), zeros(out))
 
 function (m::GRUCell)(h, x)
   b, o = m.b, size(h, 1)

src/optimise/train.jl

@@ -7,6 +7,9 @@ function update!(x::AbstractArray, x̄)
 end
 
 function update!(opt, x, x̄)
+  if x̄ == nothing
+    x̄ = zeros(size(x)...)
+  end
   update!(x, -apply!(opt, x, x̄))
 end