fix!: change the default layernorm dims

src/api/layernorm.jl

@@ -1,6 +1,6 @@
 @doc doc"""
-    layernorm(x, scale, bias, σ = identity, dims=Colon(),
-        epsilon = eps(eltype(x)) ^ (5 / 7))
+    layernorm(x::AbstractArray{xT, N}, scale, bias, σ = identity, dims=1:(N - 1),
+        epsilon = eps(eltype(x)) ^ (5 / 7)) where {xT, N}
 
 Layer Normalization. For details see [1].
 
@@ -18,17 +18,13 @@ and applies the activation function `σ` elementwise to `y`.
   - `scale`: Scale factor (``\gamma``) (can be `nothing`)
   - `bias`: Bias factor (``\beta``) (can be `nothing`)
   - `σ`: Activation function (default: `identity`)
-  - `dims`: Dimensions along which the mean and std of `x` is computed (default: `Colon()`).
-     If `nothing` is passed, the dims are inferred based on the dimensions of scale and
-     bias. For example, if `x` is `N` dimensional and `scale` and `bias` are `M`
-     dimensional, then the dims will be `1:(N - M)`.
+  - `dims`: Dimensions along which the mean and std of `x` is computed. If `nothing` is
+    passed, the dims are inferred based on the dimensions of scale and bias. For example,
+    if `x` is `N` dimensional and `scale` and `bias` are `M` dimensional, then the dims
+    will be `1:(N - M)`.
   - `epsilon`: Value added to the denominator for numerical stability
     (default: `eps(eltype(x)) ^ (5 / 7)`)
 
-!!! danger "Default `dims` to be changed in v1"
-
-    By default, `dims` will exclude the batch dimension.
-
 ## Returns
 
 Normalized Array of same size as `x`.
@@ -38,9 +34,9 @@ Normalized Array of same size as `x`.
 [1] Ba, Jimmy Lei, Jamie Ryan Kiros, and Geoffrey E. Hinton. "Layer normalization." arXiv
     preprint arXiv:1607.06450 (2016).
 """
-function layernorm(x::AbstractArray{xT}, scale::Optional{<:AbstractArray},
-        bias::Optional{<:AbstractArray}, σ::F=identity, dims=Colon(),
-        epsilon::Real=default_epsilon(x)) where {F, xT}
+function layernorm(x::AbstractArray{xT, N}, scale::Optional{<:AbstractArray},
+        bias::Optional{<:AbstractArray}, σ::F=identity, dims=1:(N - 1),
+        epsilon::Real=default_epsilon(x)) where {F, xT, N}
     return layernorm_impl(
         x, scale, bias, select_fastest_activation(σ, x, scale, bias), dims, epsilon)
 end