Make LDF <: AbstractModel

[penelopeysm]

See TuringLang/Turing.jl#2555 -- this is one of the necessary steps, or else you'll get errors like

julia> sample(ldf, NUTS(), 100)
ERROR: MethodError: no method matching mcmcsample(::Random.TaskLocalRNG, ::LogDensityFunction{…}, ::DynamicPPL.Sampler{…}, ::Int64; chain_type::UnionAll, progress::Bool)
The function `mcmcsample` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  mcmcsample(::Random.AbstractRNG, ::AbstractMCMC.AbstractModel, ::AbstractMCMC.AbstractSampler, ::Integer; progress, progressname, callback, num_warmup, discard_initial, thinning, chain_type, initial_state, kwargs...)

This really shouldn't change anything in DynamicPPL.

[github-actions]

Benchmark Report for Commit a22771d

Computer Information

Julia Version 1.11.5
Commit 760b2e5b739 (2025-04-14 06:53 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 4 × AMD EPYC 7763 64-Core Processor
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, znver3)
Threads: 1 default, 0 interactive, 1 GC (on 4 virtual cores)

Benchmark Results

|                 Model | Dimension |  AD Backend |      VarInfo Type | Linked | Eval Time / Ref Time | AD Time / Eval Time |
|-----------------------|-----------|-------------|-------------------|--------|----------------------|---------------------|
| Simple assume observe |         1 | forwarddiff |             typed |  false |                  9.4 |                 1.6 |
|           Smorgasbord |       201 | forwarddiff |             typed |  false |                723.4 |                33.8 |
|           Smorgasbord |       201 | forwarddiff | simple_namedtuple |   true |                357.6 |                53.7 |
|           Smorgasbord |       201 | forwarddiff |           untyped |   true |               1188.1 |                28.1 |
|           Smorgasbord |       201 | forwarddiff |       simple_dict |   true |               3272.7 |                24.1 |
|           Smorgasbord |       201 | reversediff |             typed |   true |               1441.6 |                29.3 |
|           Smorgasbord |       201 |    mooncake |             typed |   true |                956.2 |                 5.2 |
|    Loop univariate 1k |      1000 |    mooncake |             typed |   true |               5381.6 |                 4.1 |
|       Multivariate 1k |      1000 |    mooncake |             typed |   true |                993.6 |                 9.0 |
|   Loop univariate 10k |     10000 |    mooncake |             typed |   true |              60707.9 |                 3.6 |
|      Multivariate 10k |     10000 |    mooncake |             typed |   true |               8526.6 |                10.0 |
|               Dynamic |        10 |    mooncake |             typed |   true |                143.6 |                11.6 |
|              Submodel |         1 |    mooncake |             typed |   true |                 13.0 |                 6.5 |
|                   LDA |        12 | reversediff |             typed |   true |                445.5 |                 5.6 |

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.91%. Comparing base (e350cd3) to head (a22771d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #937   +/-   ##
=======================================
  Coverage   82.91%   82.91%           
=======================================
  Files          36       36           
  Lines        3962     3962           
=======================================
  Hits         3285     3285           
  Misses        677      677           

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[coveralls]

Pull Request Test Coverage Report for Build 15240168224

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 58 unchanged lines in 5 files lost coverage.
• Overall coverage remained the same at 83.08%

---

Files with Coverage Reduction	New Missed Lines	%
src/experimental.jl	3	0.0%
src/varinfo.jl	4	84.14%
src/logdensityfunction.jl	14	50.0%
ext/DynamicPPLJETExt.jl	16	0.0%
src/test_utils/ad.jl	21	0.0%

Totals
Change from base Build 15213861039:	0.0%
Covered Lines:	3285
Relevant Lines:	3954

---

💛 - Coveralls