Rename kwarg to exclude instead of predicate. Add test for nested exclusion.

Author: darsnack

README.md

@@ -72,7 +72,7 @@ It is also possible to implement `functor` by hand when greater flexibility is r
 
 For a discussion regarding the need for a `cache` in the implementation of `fmap`, see [here](https://github.com/FluxML/Functors.jl/issues/2).
 
-Use `predicate` for more fine-grained control over whether `fmap` descends into a particular value (the default is `predicate = Functors.isleaf`):
+Use `exclude` for more fine-grained control over whether `fmap` descends into a particular value (the default is `exclude = Functors.isleaf`):
 ```julia
 julia> using CUDA
 
@@ -84,7 +84,7 @@ julia> fmap(cu, x)
  'b': ASCII/Unicode U+0062 (category Ll: Letter, lowercase)
  'c': ASCII/Unicode U+0063 (category Ll: Letter, lowercase)
 
-julia> fmap(cu, x; predicate = CUDA.isbitstype(eltype(x)))
+julia> fmap(cu, x; exclude = x -> CUDA.isbitstype(eltype(x)))
 3-element CuArray{Char,1}:
  'a': ASCII/Unicode U+0061 (category Ll: Letter, lowercase)
  'b': ASCII/Unicode U+0062 (category Ll: Letter, lowercase)

src/functor.jl

@@ -51,9 +51,12 @@ end
 
 # See https://github.com/FluxML/Functors.jl/issues/2 for a discussion regarding the need for
 # cache.
-function fmap(f, x; predicate = isleaf, cache = IdDict())
+function fmap(f, x; exclude = isleaf, cache = IdDict())
   haskey(cache, x) && return cache[x]
-  cache[x] = predicate(x) ? f(x) : fmap1(x -> fmap(f, x, cache = cache), x)
+  y = exclude(x) ? f(x) : fmap1(x -> fmap(f, x, cache = cache, exclude = exclude), x)
+  cache[x] = y
+
+  return y
 end
 
 """

test/basics.jl

@@ -32,13 +32,17 @@ end
   @test model′.x.y isa Vector{Float64}
 end
 
-@testset "Predicate" begin
+@testset "Exclude" begin
   f(x::AbstractArray) = x
   f(x::Char) = 'z'
 
   x = ['a', 'b', 'c']
   @test fmap(f, x)  == ['z', 'z', 'z']
-  @test fmap(f, x; predicate = x -> x isa AbstractArray) == x
+  @test fmap(f, x; exclude = x -> x isa AbstractArray) == x
+
+  x = (['a', 'b', 'c'], ['d', 'e', 'f'])
+  @test fmap(f, x)  == (['z', 'z', 'z'], ['z', 'z', 'z'])
+  @test fmap(f, x; exclude = x -> x isa AbstractArray) == x
 end
 
 @testset "Property list" begin