Overloading `Base.show`

[torfjelde]

Currently we've done nothing to improve the "visual inspection" of objects. At the moment it can be very difficult for the user to inspect a Bijector. And with PR #44 we're going to also have dimensionality in the type which makes it even more important to easily be able to inspect a Bijector.

Sooo let's have another poll! Which of the following styles do you prefer:

1. Distributions.jl-style and Dims=1 for "container" types, e.g. Composed and Stacked

   
   julia> Bijectors.Exp()
   Exp{0}()

julia> Bijectors.Logit(0.0, 1.0) Logit{Float64}(a=0.0, b=1.0)

julia> Bijectors.composel([PlanarLayer(10) for i = 1:3]...) Composed{..., Dims=1}(ts=(PlanarLayer{Array{Float64,2},Array{Float64,1}}( w: [-1.10143; 1.33204; … ; -0.725184; -0.279187] u: [-0.755879; 1.6483; … ; 1.15966; -0.164425] b: [0.09642] ) , PlanarLayer{Array{Float64,2},Array{Float64,1}}( w: [-0.913726; -2.03212; … ; 0.0719403; -0.0622856] u: [-1.28574; -0.0194101; … ; -0.760258; 0.555373] b: [-0.951921] ) , PlanarLayer{Array{Float64,2},Array{Float64,1}}( w: [1.14896; 0.710024; … ; -2.24741; -0.904142] u: [0.917471; 1.07336; … ; -1.01782; 0.230862] b: [0.535096] ) ))

2. Distributions.jl-style
```julia
julia> Bijectors.Exp()
Exp{0}()

julia> Bijectors.Logit(0.0, 1.0)
Logit{Float64}(a=0.0, b=1.0)

julia> Bijectors.composel([PlanarLayer(10) for i = 1:3]...)
Composed(ts=(PlanarLayer{Array{Float64,2},Array{Float64,1}}(
w: [1.67265; -0.888749; … ; -1.3403; -0.0615207]
u: [0.741016; 0.355929; … ; -1.22854; 0.5851]
b: [1.00029]
)
, PlanarLayer{Array{Float64,2},Array{Float64,1}}(
w: [0.401001; -0.586282; … ; 0.359551; 0.736369]
u: [1.26738; -0.194372; … ; 1.13786; -0.0398834]
b: [1.08065]
)
, PlanarLayer{Array{Float64,2},Array{Float64,1}}(
w: [-1.01392; -0.70209; … ; -1.8464; 0.212027]
u: [-0.726696; -2.39618; … ; -0.169901; -0.526239]
b: [1.02857]
)
))

3. Current one:

   
   julia> Bijectors.Exp()
   Exp{0}()

julia> Bijectors.Logit(0.0, 1.0) Logit{Float64}(0.0, 1.0)

julia> Bijectors.composel([PlanarLayer(10) for i = 1:3]...) Composed{Tuple{PlanarLayer{Array{Float64,2},Array{Float64,1}},PlanarLayer{Array{Float64,2},Array{Float64,1}},PlanarLayer{Array{Float64,2},Array{Float64,1}}},1}((PlanarLayer{Array{Float64,2},Array{Float64,1}}([0.700402; -0.489015; … ; -1.31095; -1.94269], [-0.199911; 1.38871; … ; -0.464837; 0.853309], [0.0885244]), PlanarLayer{Array{Float64,2},Array{Float64,1}}([-0.238407; -0.00701318; … ; 0.921103; 1.26528], [-0.17988; -0.0505573; … ; -0.886066; 1.18275], [0.467128]), PlanarLayer{Array{Float64,2},Array{Float64,1}}([0.231724; 0.39539; … ; -0.418577; -1.75923], [-0.055946; 1.37152; … ; 1.26864; -1.2355], [-0.636524])))

To vote: :+1: : for (1), :confused: for (2), and :-1: for (3).

Other suggestions welcome!

[trappmartin]

How does 1 differ from 2?

[torfjelde]

The {..., Dims=1} in Composed. After #44 we'll have dimension information in Bijector, and in the case of these "wrapper" bijectors, e.g. Composed, it could be nice to show the dimensionality of the bijector:)

[torfjelde]

We can also drop the Dims= and just write the dimensionality N, which is similar to what you get by default for all other bijectors, e.g. Exp() is displayed as Exp{0}() because by default we assume Exp to be 0-dimensional (can also instantiate as Exp{N}() where N is an integer)

[trappmartin]

I see, I think the dims is a good idea.

[torfjelde]

You can see how the README will look with dimensionality from PR #44 combined with the proposed Base.show overload over at https://github.com/torfjelde/Bijectors.jl/tree/tor/show-overload

[trappmartin]

Would it make sense to use lower-case dim instead of Dim? I think this would be more julia style.

[torfjelde]

I'm not necessarily against that; my reasoning for choosing Dim is because it's a type-parameter rather than an argument. Could also rename to D or dim as you suggested :)