Rework VarInfo printing

[mhauru]

Our current use of show for VarInfo is quite inconsistent. In:

module MWE

using DynamicPPL, Distributions, LinearAlgebra

function print(vi, name)
    println("\n\n============================ $name ============================\n")
    println("# DISPLAY")
    display(vi)
    println("\n# SHOW")
    show(vi)
end

@model function f()
   x ~ Normal()
   y ~ MvNormal(Diagonal(fill(abs(x), 2)))
end

print(DynamicPPL.untyped_varinfo(f()), "UNTYPED")
print(DynamicPPL.typed_varinfo(f()), "TYPED")
print(DynamicPPL.SimpleVarInfo(f()), "SIMPLE")
print(DynamicPPL.ThreadSafeVarInfo(DynamicPPL.untyped_varinfo(f())), "THREADSAFE UNTYPED")
end

Out:

============================ UNTYPED ============================

# DISPLAY
/=======================================================================
| VarInfo
|-----------------------------------------------------------------------
| Varnames  :   AbstractPPL.VarName[x, y]
| Range     :   UnitRange{Int64}[1:1, 2:3]
| Vals      :   Real[0.6393339904991309, -2.1020960714862715, 0.21204297326010874]
| Orders    :   [0, 0]
| Logp      :   -6.004814519363116
| #produce  :   0
| flags     :   Dict{String, BitVector}("del" => [0, 0], "trans" => [0, 0])
\=======================================================================


# SHOW
VarInfo (2 variables (y, x), dimension 3; logp: -6.005)

============================ TYPED ============================

# DISPLAY
DynamicPPL.TypedVarInfo{@NamedTuple{x::DynamicPPL.Metadata{Dict{AbstractPPL.VarName{:x, typeof(identity)}, Int64}, Vector{Distributions.Normal{Float64}}, Vector{AbstractPPL.VarName{:x, typeof(identity)}}, Vector{Float64}}, y::DynamicPPL.Metadata{Dict{AbstractPPL.VarName{:y, typeof(identity)}, Int64}, Vector{Distributions.ZeroMeanDiagNormal{Tuple{Base.OneTo{Int64}}}}, Vector{AbstractPPL.VarName{:y, typeof(identity)}}, Vector{Float64}}}, Float64}((x = DynamicPPL.Metadata{Dict{AbstractPPL.VarName{:x, typeof(identity)}, Int64}, Vector{Distributions.Normal{Float64}}, Vector{AbstractPPL.VarName{:x, typeof(identity)}}, Vector{Float64}}(Dict(x => 1), [x], UnitRange{Int64}[1:1], [-1.250616290583678], Distributions.Normal{Float64}[Distributions.Normal{Float64}(μ=0.0, σ=1.0)], [0], Dict{String, BitVector}("del" => [0], "trans" => [0])), y = DynamicPPL.Metadata{Dict{AbstractPPL.VarName{:y, typeof(identity)}, Int64}, Vector{Distributions.ZeroMeanDiagNormal{Tuple{Base.OneTo{Int64}}}}, Vector{AbstractPPL.VarName{:y, typeof(identity)}}, Vector{Float64}}(Dict(y => 1), [y], UnitRange{Int64}[1:2], [0.7503094371292123, 0.3255295112123813], Distributions.ZeroMeanDiagNormal{Tuple{Base.OneTo{Int64}}}[ZeroMeanDiagNormal(
dim: 2
μ: Zeros(2)
Σ: [1.250616290583678 0.0; 0.0 1.250616290583678]
)
], [0], Dict{String, BitVector}("del" => [0], "trans" => [0]))), Base.RefValue{Float64}(-4.029914243271634), Base.RefValue{Int64}(0))

# SHOW
DynamicPPL.TypedVarInfo{@NamedTuple{x::DynamicPPL.Metadata{Dict{AbstractPPL.VarName{:x, typeof(identity)}, Int64}, Vector{Distributions.Normal{Float64}}, Vector{AbstractPPL.VarName{:x, typeof(identity)}}, Vector{Float64}}, y::DynamicPPL.Metadata{Dict{AbstractPPL.VarName{:y, typeof(identity)}, Int64}, Vector{Distributions.ZeroMeanDiagNormal{Tuple{Base.OneTo{Int64}}}}, Vector{AbstractPPL.VarName{:y, typeof(identity)}}, Vector{Float64}}}, Float64}((x = DynamicPPL.Metadata{Dict{AbstractPPL.VarName{:x, typeof(identity)}, Int64}, Vector{Distributions.Normal{Float64}}, Vector{AbstractPPL.VarName{:x, typeof(identity)}}, Vector{Float64}}(Dict(x => 1), [x], UnitRange{Int64}[1:1], [-1.250616290583678], Distributions.Normal{Float64}[Distributions.Normal{Float64}(μ=0.0, σ=1.0)], [0], Dict{String, BitVector}("del" => [0], "trans" => [0])), y = DynamicPPL.Metadata{Dict{AbstractPPL.VarName{:y, typeof(identity)}, Int64}, Vector{Distributions.ZeroMeanDiagNormal{Tuple{Base.OneTo{Int64}}}}, Vector{AbstractPPL.VarName{:y, typeof(identity)}}, Vector{Float64}}(Dict(y => 1), [y], UnitRange{Int64}[1:2], [0.7503094371292123, 0.3255295112123813], Distributions.ZeroMeanDiagNormal{Tuple{Base.OneTo{Int64}}}[ZeroMeanDiagNormal(
dim: 2
μ: Zeros(2)
Σ: [1.250616290583678 0.0; 0.0 1.250616290583678]
)
], [0], Dict{String, BitVector}("del" => [0], "trans" => [0]))), Base.RefValue{Float64}(-4.029914243271634), Base.RefValue{Int64}(0))

============================ SIMPLE ============================

# DISPLAY
SimpleVarInfo((x = 0.15360503384997595, y = [-0.023559980538471543, 0.19884647851374856]), -1.0257554501131314)

# SHOW
DynamicPPL.SimpleVarInfo{@NamedTuple{x::Float64, y::Vector{Float64}}, Float64, DynamicPPL.NoTransformation}((x = 0.15360503384997595, y = [-0.023559980538471543, 0.19884647851374856]), -1.0257554501131314, DynamicPPL.NoTransformation())

============================ THREADSAFE UNTYPED ============================

# DISPLAY
DynamicPPL.ThreadSafeVarInfo{DynamicPPL.UntypedVarInfo{DynamicPPL.Metadata{Dict{AbstractPPL.VarName, Int64}, Vector{Distributions.Distribution}, Vector{AbstractPPL.VarName}, Vector{Real}}, Float64}, Vector{Base.RefValue{Float64}}}(VarInfo (2 variables (y, x), dimension 3; logp: -3.004), Base.RefValue{Float64}[Base.RefValue{Float64}(0.0)])

# SHOW
DynamicPPL.ThreadSafeVarInfo{DynamicPPL.UntypedVarInfo{DynamicPPL.Metadata{Dict{AbstractPPL.VarName, Int64}, Vector{Distributions.Distribution}, Vector{AbstractPPL.VarName}, Vector{Real}}, Float64}, Vector{Base.RefValue{Float64}}}(VarInfo (2 variables (y, x), dimension 3; logp: -3.004), Base.RefValue{Float64}[Base.RefValue{Float64}(0.0)])Main.MWE

Note that display results in a call to show(io, ::MIME"text/plain", vi), which is meant to produce a nice, human-readable output. show on the other hand goes to show(io, vi), which should produce something that includes full details about the object, enough to reconstruct it, preferably as valid Julia code.

Two things should be fixed:

• We are violating the second rule at least with UntypedVarInfo, i.e. show(vi) is not a dump of vi as valid code.
• We are inconsistent in what we produce with display for the pretty print. TypedVarInfo and ThreadSafeVarInfo just fall back to show(vi) which is not very readable. SimpleVarInfo and UntypedVarInfo both do have nice print outs, though they are quite different.

This issue supersedes #243.

[penelopeysm]

Save the forests, don't print VarInfos!

[mhauru]

Closed by #1183

[penelopeysm]

Nicer printing in #1218.