forgotten changes

Author: mcabbott

src/Fluxperimental.jl

@@ -12,6 +12,7 @@ export shinkansen!
 include("chain.jl")
 
 include("compact.jl")
+export @compact
 
 include("noshow.jl")
 export NoShow

src/compact.jl

@@ -4,64 +4,66 @@ import Flux: _big_show
     @compact(forward::Function; name=nothing, parameters...)
 
 Creates a layer by specifying some `parameters`, in the form of keywords,
-and (usually as a `do` block) a function for the forward pass.
+and a function for the forward pass (often as a `do` block).
+
 You may think of `@compact` as a specialized `let` block creating local variables 
 that are trainable in Flux.
 Declared variable names may be used within the body of the `forward` function.
 
-Here is a linear model:
+# Examples
+
+Here is a linear model, equivalent to `Flux.Scale`:
 
 ```
-r = @compact(w = rand(3)) do x
-  w .* x
-end
-r([1, 1, 1])  # x is set to [1, 1, 1].
+using Flux, Fluxperimental
+
+w = rand(3)
+sc = @compact(x -> x .* w; w)
+
+sc([1 10 100])  # 3×3 Matrix as output.
+ans ≈ Flux.Scale(w)([1 10 100])  # equivalent Flux layer
 ```
 
-Here is a linear model with bias and activation:
+Here is a linear model with bias and activation, equivalent to Flux's `Dense` layer.
+The forward pass function is now written as a do block, instead of `x -> begin y = W * x; ...`
 
 ```
-d_in = 5
+d_in = 3
 d_out = 7
-d = @compact(W = randn(d_out, d_in), b = zeros(d_out), act = relu) do x
+layer = @compact(W = randn(d_out, d_in), b = zeros(d_out), act = relu) do x
   y = W * x
   act.(y .+ b)
 end
-d(ones(5, 10)) # 7×10 Matrix as output.
-d([1,2,3,4,5]) ≈ Dense(d.variables.W, zeros(7), relu)([1,2,3,4,5]) # Equivalent to a dense layer
+
+den = Dense(layer.variables.W, zeros(7), relu)([1,2,3])  # equivalent Flux layer
+layer(ones(3, 10)) ≈ layer(ones(3, 10))  # 7×10 Matrix as output.
 ``` 
-```
 
-Finally, here is a simple MLP:
+Finally, here is a simple MLP, equivalent to a `Chain` with 5 `Dense` layers:
 
 ```
-using Flux
-
-n_in = 1
-n_out = 1
+d_in = 1
 nlayers = 3
 
 model = @compact(
-  w1=Dense(n_in, 128),
-  w2=[Dense(128, 128) for i=1:nlayers],
-  w3=Dense(128, n_out),
-  act=relu
+  lay1 = Dense(d_in => 64),
+  lay234 = [Dense(64 => 64) for i=1:nlayers],
+  wlast = rand32(64),
 ) do x
-  embed = act(w1(x))
-  for w in w2
-    embed = act(w(embed))
+  y = tanh.(lay1(x))
+  for lay in lay234
+    y = relu.(lay(y))
   end
-  out = w3(embed)
-  return out
+  return wlast' * y
 end
 
-model(randn(n_in, 32))  # 1×32 Matrix as output.
+model(randn(Float32, d_in, 8))  # 1×8 array as output.
 ```
 
-We can train this model just like any `Chain`:
+We can train this model just like any `Chain`, for example:
 
 ```
-data = [([x], 2x-x^3) for x in -2:0.1f0:2]
+data = [([x], [2x-x^3]) for x in -2:0.1f0:2]
 optim = Flux.setup(Adam(), model)
 
 for epoch in 1:1000
@@ -71,19 +73,23 @@ end
 To specify a custom printout for the model, you may find [`NoShow`](@ref) useful.
 """
 macro compact(_exs...)
+  _compact(_exs...) |> esc
+end
+
+function _compact(_exs...)
   # check inputs, extracting function expression fex and unprocessed keyword arguments _kwexs
-  isempty(_exs) && error("expects at least two expressions: a function and at least one keyword")
+  isempty(_exs) && error("@compact expects at least two expressions: a function and at least one keyword")
   if Meta.isexpr(_exs[1], :parameters)
-    length(_exs) >= 2 || error("expects an anonymous function")
+    length(_exs) >= 2 || error("@compact expects an anonymous function")
     fex = _exs[2]
     _kwexs = (_exs[1], _exs[3:end]...)
   else
     fex = _exs[1]
     _kwexs = _exs[2:end]
   end
-  Meta.isexpr(fex, :(->)) || error("expects an anonymous function")
-  isempty(_kwexs) && error("expects keyword arguments")
-  all(ex -> Meta.isexpr(ex, (:kw,:(=),:parameters)), _kwexs) || error("expects only keyword arguments")
+  Meta.isexpr(fex, :(->)) || error("@compact expects an anonymous function")
+  isempty(_kwexs) && error("@compact expects keyword arguments")
+  all(ex -> Meta.isexpr(ex, (:kw,:(=),:parameters)), _kwexs) || error("@compact expects only keyword arguments")
 
   # process keyword arguments
   if Meta.isexpr(_kwexs[1], :parameters) # handle keyword arguments provided after semicolon
@@ -101,20 +107,20 @@ macro compact(_exs...)
           fex_args = fex.args[1]
           isa(fex_args, Symbol) ? string(fex_args) : join(fex_args.args, ", ")
       catch e 
-        @warn "Function stringifying does not yet handle all cases. Falling back to empty string for input arguments"
-        ""
+        @warn """@compact's function stringifying does not yet handle all cases. Falling back to "?" """ maxlog=1
+        "?"
       end
-  block = string(Base.remove_linenums!(fex).args[2])
+  block = string(Base.remove_linenums!(fex).args[2])  # TODO make this remove macro comments
 
   # edit expressions
   vars = map(ex -> ex.args[1], kwexs)
-  fex = supportself(fex, vars)
+  fex = _supportself(fex, vars)
 
   # assemble
-  return esc(:($CompactLayer($fex, ($input, $block); $(kwexs...))))
+  return :($CompactLayer($fex, ($input, $block); $(kwexs...)))
 end
 
-function supportself(fex::Expr, vars)
+function _supportself(fex::Expr, vars)
   @gensym self
   @gensym curried_f
   # To avoid having to manipulate fex's arguments and body explicitly, we form a curried function first
@@ -174,7 +180,7 @@ function Flux._big_show(io::IO, obj::CompactLayer, indent::Int=0, name=nothing)
       print(io, " "^indent, post)
     end
 
-    input != "" && print(io, " do ", input)
+    print(io, " do ", input)
     if block != ""
       block_to_print = block[6:end]
       # Increase indentation of block according to `indent`: