Merge e21b094 into bb88c55

docs/src/training/training.md

@@ -70,6 +70,10 @@ Such an object contains a reference to the model's parameters, not a copy, such
 
 Handling all the parameters on a layer by layer basis is explained in the [Layer Helpers](../models/basics.md) section. Also, for freezing model parameters, see the [Advanced Usage Guide](../models/advanced.md).
 
+```@docs
+Flux.params
+```
+
 ## Datasets
 
 The `data` argument of `train!` provides a collection of data to train with (usually a set of inputs `x` and target outputs `y`). For example, here's a dummy dataset with only one data point:

src/functor.jl

@@ -48,6 +48,25 @@ function params!(p::Params, x, seen = IdSet())
   end
 end
 
+"""
+    params(model)
+    params(layers...)
+
+Given a model or specific layers from a model, create a `Params` object pointing to its trainable parameters.
+
+This can be used with the `gradient` function, see [Taking Gradients](@ref), or as input to the [`Flux.train!`](@ref Flux.train!) function.
+
+The behaviour of `params` on custom types can be customized using [`Functor.@functor`](@ref) or [`Flux.trainable`](@ref).
+
+# Examples
+```jldoctest
+julia> params(Chain(Dense(ones(2,3))), softmax)
+Params([[1.0 1.0 1.0; 1.0 1.0 1.0], [0.0, 0.0]])
+
+julia> params(BatchNorm(2, relu))
+Params([Float32[0.0, 0.0], Float32[1.0, 1.0]])
+```
+"""
 function params(m...)
   ps = Params()
   params!(ps, m)