naive implementation of activations

src/layers/basic.jl

@@ -40,7 +40,23 @@ function Base.show(io::IO, c::Chain)
   print(io, ")")
 end
 
-activations(c::Chain, x) = accumulate((x, m) -> m(x), c.layers, init = x)
+
+"""
+    activations(c::Union{Chain, Any}, x)
+Calculate the forward results of each layers in Chain `c`
+"""
+activations(m, x) = activations(Chain(m), x)
+function activations(c::Chain, x)
+    rst = [c[1](x), ]
+    if length(c) == 1
+        return rst
+    end
+    for l in c[2:end]
+        push!(rst, l(rst[end]))
+    end
+    return rst
+end
+
 
 """
     Dense(in::Integer, out::Integer, σ = identity)

test/layers/basic.jl

@@ -1,4 +1,18 @@
 using Test, Random
+import Flux: activations
+
+@testset "helpers" begin
+    @testset "activations" begin
+        dummy_model = Chain(Dense(10,5,σ),Dense(5,2),softmax)
+        x = rand(10)
+        @test_nowarn activations(dummy_model[1], x)
+        @test_nowarn activations(dummy_model[1:end-1], x)
+        @test_nowarn activations(dummy_model, x)
+
+        @test activations(dummy_model, x)[1] == dummy_model[1](x)
+        @test activations(dummy_model, x)[2] == x |> dummy_model[1] |> dummy_model[2]
+    end
+end
 
 @testset "basic" begin
     @testset "Chain" begin