update Embedding constructor

Updated Embedding constructor to use `=>` and added OneHotLikeVector and OneHotLikeMatrix consts.

src/layers/basic.jl

@@ -431,7 +431,7 @@ function Base.show(io::IO, m::Parallel)
 end
 
 """
-    Embedding(in, out; init=randn)
+    Embedding(in => out; init=randn)
 
 A lookup table that stores embeddings of dimension `out` 
 for a vocabulary of size `in`. 
@@ -466,7 +466,7 @@ end
 
 @functor Embedding
 
-Embedding(in::Integer, out::Integer; init = randn32) = Embedding(init(out, in))
+Embedding(dims::Pair{<:Integer, <:Integer}; init = randn32) = Embedding(init(last(dims), first(dims)))
 
 (m::Embedding)(x::Union{OneHotVector, OneHotMatrix}) = m.weight * x # equivalent to m.weight[:,onecold(x)]
 (m::Embedding)(x::Integer) = m([x])

src/onehot.jl

@@ -46,6 +46,9 @@ const OneHotLike{T, L, N, var"N+1", I} =
   Union{OneHotArray{T, L, N, var"N+1", I},
         Base.ReshapedArray{Bool, var"N+1", <:OneHotArray{T, L, <:Any, <:Any, I}}}
 
+const OneHotLikeVector{T, L} = OneHotLike{T, L, 0, 1, T}
+const OneHotLikeMatrix{T, L, I} = OneHotLike{T, L, 1, 2, I}  
+
 _isonehot(x::OneHotArray) = true
 _isonehot(x::Base.ReshapedArray{<:Any, <:Any, <:OneHotArray{<:Any, L}}) where L = (size(x, 1) == L)
 

test/cuda/layers.jl

@@ -262,8 +262,8 @@ end
 
 @testset "Embedding" begin
   vocab_size, embed_size = 5, 2
-  m = Flux.Embedding(vocab_size, embed_size)
-
+  m = Flux.Embedding(vocab_size => embed_size)
+  
   x = [1, 3, 5]
   y = m(x)
   m_g = m |> gpu

test/layers/basic.jl

@@ -194,7 +194,7 @@ import Flux: activations
 
   @testset "Embedding" begin
     vocab_size, embed_size = 10, 4
-    m = Flux.Embedding(vocab_size, embed_size)
+    m = Flux.Embedding(vocab_size => embed_size)
     @test size(m.weight) == (embed_size, vocab_size)
 
     x = rand(1:vocab_size, 3)