Use subsumes in subset

[torfjelde]

I was using the new (experimental) Gibbs sampler in Turing.jl (TuringLang/Turing.jl#2099) I realized that there the current subset functionality, which enables the new Gibbs sampler, is not quite flexible enough to handle all the cases that the current Gibbs sampler can.

In particular, we need to use subsumes in subset rather than require explicit presence of the VarName we're interested in.

The reason for this is to support models where the size of the support might be changing. For example:

julia> using Distributions, DynamicPPL

julia> @model function demo()
           n ~ Categorical(10)
           x = Vector{Float64}(undef, n)
           for i = 1:n
               x[i] ~ Normal()
           end
       end
demo (generic function with 2 methods)

julia> model = demo();

julia> varinfo = VarInfo();

julia> DynamicPPL.evaluate!!(model, varinfo)

Suppose I now want to do:

subset(varinfo, @varname(x))

That is currently not possible since we only allow passing varnames that are explicit present in the varinfo. And so in the above example we have to constantly query the varinfo for which x[i] are present, which we'd have to do using subsumes, and then call subset with these.

It seems a common enough pattern to me that it's worth just using subsumes already in the impl of subset so we avoid these annoyances on the user-side.

Note that this is technically not prohibiting feature-parity with the existing Gibbs sampler, as we could implement this subsumes filtering in the Gibbs sampler itself before calling subset, but this PR just seems cleaner IMO.

[coveralls]

Pull Request Test Coverage Report for Build 8701844296

Details

• 10 of 10 (100.0%) changed or added relevant lines in 3 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.2%) to 84.973%

---

Files with Coverage Reduction	New Missed Lines	%
src/compiler.jl	1	93.69%
src/simple_varinfo.jl	1	85.87%

Totals
Change from base Build 8111716086:	0.2%
Covered Lines:	2720
Relevant Lines:	3201

---

💛 - Coveralls

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.56%. Comparing base (6a2454f) to head (8bdf5f6).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #587      +/-   ##
==========================================
- Coverage   84.47%   83.56%   -0.91%     
==========================================
  Files          28       28              
  Lines        3207     3212       +5     
==========================================
- Hits         2709     2684      -25     
- Misses        498      528      +30     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[torfjelde]

@devmotion @yebai might want to have a lookk at this

[yebai]

Looks good except for a clarity question below.

[yebai]

I don't get this. Is this related to this PR, or just an unrelated bugfix?

[torfjelde]

Unrelated bugfix. Had a typo in the tests so we weren't actually testing SimpleVarInfo at all before; discovered the bug when I fixed the tests.