correct the function behavior; support Any type

src/layers/basic.jl

@@ -41,15 +41,18 @@ function Base.show(io::IO, c::Chain)
 end
 
 
+# This is a temporary and naive inplementation
+# see issue https://github.com/FluxML/Flux.jl/issues/702
 """
     activations(c::Chain, x)
 Calculate the forward results of each layers in Chain `c`
 """
 function activations(c::Chain, x)
+  rst = Array{Any,1}()
   if isempty(c)
-    return [x, ]
+    return rst
   end
-  rst = [x, c[1](x)]
+  push!(rst, c[1](x))
   for l in c[2:end]
     push!(rst, l(rst[end]))
   end

test/layers/basic.jl

@@ -6,9 +6,11 @@ import Flux: activations
     @testset "activations" begin
       dummy_model = Chain(Dense(10,5,σ),Dense(5,2),softmax)
       x = rand(10)
-      @test activations(Chain(), x) == [x, ]
+      @test activations(Chain(), x) == []
-      @test activations(dummy_model, x)[2] == dummy_model[1](x)
+      @test activations(dummy_model, x)[1] == dummy_model[1](x)
-      @test activations(dummy_model, x)[3] == x |> dummy_model[1] |> dummy_model[2]
+      @test activations(dummy_model, x)[2] == x |> dummy_model[1] |> dummy_model[2]
+
+      @test_nowarn activations(Chain(identity, x->:foo), 1) # different types
     end
   end