use nnlib for activations

REQUIRE

@@ -2,3 +2,4 @@ julia 0.6.0
 DataFlow 0.2.1 0.3-
 Juno
 MacroTools 0.3.3
+NNlib

src/Flux.jl

@@ -5,10 +5,13 @@ module Flux
 using Juno
 using Lazy: @forward
 
-export Chain, Linear, σ, softmax
+export Chain, Linear
 
 # Zero Flux Given
 
+using NNlib
+export σ, relu, softmax
+
 include("Tracker/Tracker.jl")
 using .Tracker
 export track, back!

src/layers/stateless.jl

@@ -1,11 +1,3 @@
-# Activation Functions
-
-σ(x) = 1 / (1 + exp(-x))
-
-relu(x) = max(0, x)
-
-softmax(xs) = exp.(xs) ./ sum(exp.(xs), 2)
-
 # Cost functions
 
 mse(ŷ, y) = sumabs2(ŷ .- y)/2