more general fmap

docs/src/gpu.md

@@ -19,16 +19,16 @@ loss(x, y) # ~ 3
 
 Note that we convert both the parameters (`W`, `b`) and the data set (`x`, `y`) to cuda arrays. Taking derivatives and training works exactly as before.
 
-If you define a structured model, like a `Dense` layer or `Chain`, you just need to convert the internal parameters. Flux provides `mapparams`, which allows you to alter all parameters of a model at once.
+If you define a structured model, like a `Dense` layer or `Chain`, you just need to convert the internal parameters. Flux provides `fmap`, which allows you to alter all parameters of a model at once.
 
 ```julia
 d = Dense(10, 5, σ)
-d = mapparams(cu, d)
+d = fmap(cu, d)
 d.W # Tracked CuArray
 d(cu(rand(10))) # CuArray output
 
 m = Chain(Dense(10, 5, σ), Dense(5, 2), softmax)
-m = mapparams(cu, m)
+m = fmap(cu, m)
 d(cu(rand(10)))
 ```
 

src/Flux.jl

@@ -8,7 +8,7 @@ using Juno, Requires
 using Lazy: @forward
 
 export Chain, Dense, RNN, LSTM,
-  SGD, param, params, mapparams
+  SGD, param, params, fmap
 
 using NNlib
 export σ, relu, softmax

src/tree.jl

@@ -11,15 +11,18 @@ end
 # TODO: prewalk/postwalk with correct caching
 # This is only correct in general for idempotent functions
 
-mapparams(f, x::AbstractArray) = f(x)
-mapparams(f, x) = mapchildren(x -> mapparams(f, x), x)
+isleaf(x) = isempty(children(x))
 
-forparams(f, x) = (mapparams(x -> (f(x); x), x); return)
+fmap(f, x) = isleaf(x) ? f(x) : mapchildren(x -> fmap(f, x), x)
+ffor(f, x) = isleaf(x) ? f(x) : foreach(x -> ffor(f, x), children(x))
 
 using DataFlow: OSet
 
 function params(m)
   ps, seen = [], OSet()
-  forparams(p -> p ∉ seen && (push!(ps, p); push!(seen, p)), m)
+  ffor(m) do p
+    p isa TrackedArray && p ∉ seen &&
+      (push!(ps, p); push!(seen, p))
+  end
   return ps
 end