batching in rnns

src/layers/recurrent.jl

@@ -1,3 +1,6 @@
+# TODO: broadcasting cat
+combine(x, h) = vcat(x, h .* trues(1, size(x, 2)))
+
 # Stateful recurrence
 
 mutable struct Recur{T}
@@ -24,7 +27,7 @@ RNNCell(in::Integer, out::Integer, init = initn) =
   RNNCell(Dense(in+out, out, init = initn), track(initn(out)))
 
 function (m::RNNCell)(h, x)
-  h = m.d([x; h])
+  h = m.d(combine(x, h))
   return h, h
 end
 
@@ -51,7 +54,7 @@ LSTMCell(in, out; init = initn) =
 
 function (m::LSTMCell)(h_, x)
   h, c = h_
-  x′ = [x; h]
+  x′ = combine(x, h)
   forget, input, output, cell =
     m.forget(x′), m.input(x′), m.output(x′), m.cell(x′)
   c = forget .* c .+ input .* cell