update mxnet backend

src/activation.jl

@@ -1 +1,3 @@
-abstract Activation <: Model
+export σ
+
+σ(x) = 1 ./ (1 .+ exp.(-x))

src/backend/mxnet/graph.jl

@@ -7,7 +7,8 @@ graph(vars, model, args...) = node(model, args...)
 graph(vars, x::mx.SymbolicNode) = x
 
 # TODO: detect parameters used more than once
-function graph(vars, value::AArray)
+function graph{T<:AArray}(vars, p::Flux.Param{T})
+  value = p.x
   id = gensym()
   vars[id] = value
   return mx.Variable(id)
@@ -28,3 +29,4 @@ end
 
 node(::typeof(*), args...) = mx.dot(args...)
 node(::typeof(+), args...) = mx.broadcast_plus(args...)
+node(::typeof(σ), x) = mx.Activation(data = x, act_type = :sigmoid)

src/backend/mxnet/model.jl

@@ -7,6 +7,8 @@ end
 mxdims(dims::NTuple) =
   length(dims) == 1 ? (1, dims...) : reverse(dims)
 
+mxdims(n::Integer) = mxdims((n,))
+
 function mxargs(args)
   map(args) do kv
     arg, value = kv
@@ -37,13 +39,3 @@ function (model::MXModel)(input)
   mx.forward(model.exec)
   copy(model.exec.outputs[1])'
 end
-
-# d = Dense(20, 10)
-
-# x = randn(20)
-
-# model = mxnet(d, (20,))
-
-# d(x)
-
-# model(x)