`InitContext`, part 5 - Remove `SamplingContext`, `SampleFrom{Prior,Uniform}`, `{tilde_,}assume` #985

penelopeysm · 2025-07-10T17:00:05Z

Part 1: Adding hasvalue and getvalue to AbstractPPL
Part 2: Removing hasvalue and getvalue from DynamicPPL
Part 3: Introducing InitContext and init!!
Part 4: Using InitFromParams to implement predict, returned, and initialize_values

This is part 5/N of #967.

This PR removes everything that is no longer needed. SamplingContext, SampleFromPrior, SampleFromUniform, now have direct one-to-one replacements (albeit with slightly different behaviour since they now always overwrite variables in the varinfo).

It also removes assume and tilde_assume.

Prior to this PR we had two different kinds of assume, one with a sampler and one without. Now we only have the one without, so we can just move that definition into tilde_assume!!(::DefaultContext, ...).

Finally, tilde_assume has been subsumed into tilde_assume!! as we can just dispatch on the type of right. (Previously this wasn't possible because there was a lot of stuff about is_rhs_model, etc. etc. which was removed in #960.)

Closes #859
Closes #955

github-actions · 2025-07-20T18:03:12Z

Benchmark Report for Commit `f4e5f4b`

Computer Information

Julia Version 1.11.7
Commit f2b3dbda30a (2025-09-08 12:10 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 |                  9.0 |                 1.6 |
|           Smorgasbord |       201 | forwarddiff |             typed |  false |                679.8 |                46.1 |
|           Smorgasbord |       201 | forwarddiff | simple_namedtuple |   true |                323.9 |                74.8 |
|           Smorgasbord |       201 | forwarddiff |           untyped |   true |               1227.4 |                30.1 |
|           Smorgasbord |       201 | forwarddiff |       simple_dict |   true |               6910.3 |                29.8 |
|           Smorgasbord |       201 | reversediff |             typed |   true |               1535.0 |                29.0 |
|           Smorgasbord |       201 |    mooncake |             typed |   true |               1075.6 |                 4.6 |
|    Loop univariate 1k |      1000 |    mooncake |             typed |   true |               5944.2 |                 4.3 |
|       Multivariate 1k |      1000 |    mooncake |             typed |   true |               1037.0 |                 9.0 |
|   Loop univariate 10k |     10000 |    mooncake |             typed |   true |              66370.1 |                 4.0 |
|      Multivariate 10k |     10000 |    mooncake |             typed |   true |               9192.3 |                 9.7 |
|               Dynamic |        10 |    mooncake |             typed |   true |                136.1 |                11.8 |
|              Submodel |         1 |    mooncake |             typed |   true |                 12.9 |                 5.1 |
|                   LDA |        12 | reversediff |             typed |   true |               1205.6 |                 3.4 |

codecov · 2025-07-20T18:16:00Z

Codecov Report

❌ Patch coverage is 90.90909% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.13%. Comparing base (6d43231) to head (f4e5f4b).
⚠️ Report is 3 commits behind head on breaking.

Files with missing lines	Patch %	Lines
src/context_implementations.jl	88.23%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           breaking     #985      +/-   ##
============================================
+ Coverage     81.20%   82.13%   +0.92%     
============================================
  Files            39       39              
  Lines          3910     3811      -99     
============================================
- Hits           3175     3130      -45     
+ Misses          735      681      -54

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github-actions · 2025-07-20T18:32:57Z

DynamicPPL.jl documentation for PR #985 is available at:
https://TuringLang.github.io/DynamicPPL.jl/previews/PR985/

penelopeysm · 2025-07-26T20:45:31Z

test/ad.jl

        end
    end

-    @testset "Turing#2151: ReverseDiff compilation & eltype(vi, spl)" begin


I couldn't find a way to reproduce this test without SamplingContext and the whole tilde-pipeline machinery that this PR removes, so I think that this is no longer relevant.

Actually just for posterity I did find a way to reproduce it when I tried to remove eltype etc. in #1015. But without the changes from that PR I couldn't repro it

penelopeysm · 2025-09-18T13:04:30Z

src/context_implementations.jl

sorry this file's diff is a bit of a mess, there are no real code changes, it's just:

merged tilde_assume, tilde_assume!!, and assume into a single function (they all just called each other)

added types to the arguments

added proper docstrings

mhauru

Enjoyed this one a lot.

mhauru · 2025-09-22T09:13:24Z

docs/src/api.md

 ## Model

 ### Macros



Is it time to start a HISTORY.md entry? Might be easier to do it here were you can cross-check against what's being removed, rather than once everything is in breaking in a huge diff.

Yeah, good idea to do it in this PR. I'll write one up later and ping you again

mhauru · 2025-09-24T09:00:23Z

src/context_implementations.jl

-end
-function tilde_assume(rng::Random.AbstractRNG, ::DefaultContext, sampler, right, vn, vi)
-    return assume(rng, sampler, right, vn, vi)
+function tilde_assume!!(


To confirm that I understand how this will play out in Turing.jl: The idea is that samplers don't need to modify the behaviour of the tilde pipeline any more, and thus SamplingContext can go in its entirety, and we don't need things like tilde_assume without !! or assume. And the few that do still need to do that (Gibbs, maybe particles, hopefully nothing else) need to define their own context. Is that right?

I think so, although I'm not 100% sure. We'll probably have to do a similar process to what we did last time for accumulators: make a Turing PR that builds against the breaking branch of DPPL. Things might break. But I'm hoping it won't be too bad haha.

penelopeysm · 2025-09-24T14:03:11Z

Mildly tangential: I kind of find it weird that we do **Breaking changes** and then ### Subheading because the latter is bigger than the former. I feel like this was originally done to make JuliaRegistrator happy, but I checked again and it claims (e.g. JuliaRegistries/General#139062 (comment)) that it doesn't need to be **Breaking changes**, it can be ## Breaking changes. I'm a bit kind of tempted to reformat the changelog to make it look nicer (not in this PR).

mhauru

I, too, have disliked the bolding taking precedence over headings. Happy for that to be changed.

mhauru · 2025-09-24T15:10:12Z

HISTORY.md

+
+  - `InitContext(rng, InitFromPrior())`: New values are sampled from the prior distribution (on the right-hand side of the tilde).
+  - `InitContext(rng, InitFromUniform(a, b))`: New values are sampled uniformly from the interval `[a, b]`, and then invlinked to the support of the distribution on the right-hand side of the tilde.
+  - `InitContext(rng, InitFromParams(p, fallback))`: New values are obtained by indexing into the `p` object, which can be a `NamedTuple` or `Dict{<:VarName}`. If a variable is not found in `p`, then the `fallback` strategy is used, which is simply another of these strategies. In particular, `InitFromParams` enables the case where different variables are to be initialised from different sources.


enables the case where different variables are to be initialised from different sources.

Does this allow different sources in some broader sense than some having fixed values and others using fallback? Like could I do InitFromPrior for some and InitFromUniform for others?

That thought did pop into my mind when I was writing, which led me to mention the custom initialisation strategy just below this. You'd have to write your custom InitFromFoo, but it would be possible in that function to check e.g. the varname and dispatch to prior / uniform accordingly.

HISTORY.md

Co-authored-by: Markus Hauru <[email protected]>

penelopeysm · 2025-09-24T15:48:10Z

Day N of coveralls failing randomly...

* Bump minor version * bump benchmarks compat * add a skeletal changelog * `InitContext`, part 3 - Introduce `InitContext` (#981) * Implement InitContext * Fix loading order of modules; move `prefix(::Model)` to model.jl * Add tests for InitContext behaviour * inline `rand(::Distributions.Uniform)` Note that, apart from being simpler code, Distributions.Uniform also doesn't allow the lower and upper bounds to be exactly equal (but we might like to keep that option open in DynamicPPL, e.g. if the user wants to initialise all values to the same value in linked space). * Document * Add a test to check that `init!!` doesn't change linking * Fix `push!` for VarNamedVector This should have been changed in #940, but slipped through as the file wasn't listed as one of the changed files. * Add some line breaks Co-authored-by: Markus Hauru <[email protected]> * Add the option of no fallback for ParamsInit * Improve docstrings * typo * `p.default` -> `p.fallback` * Rename `{Prior,Uniform,Params}Init` -> `InitFrom{Prior,Uniform,Params}` --------- Co-authored-by: Markus Hauru <[email protected]> * use `varname_leaves` from AbstractPPL instead (#1030) * use `varname_leaves` from AbstractPPL instead * add changelog entry * fix import * tidy occurrences of varname_leaves as well (#1031) * `InitContext`, part 4 - Use `init!!` to replace `evaluate_and_sample!!`, `predict`, `returned`, and `initialize_values` (#984) * Replace `evaluate_and_sample!!` -> `init!!` * Use `ParamsInit` for `predict`; remove `setval_and_resample!` and friends * Use `init!!` for initialisation * Paper over the `Sampling->Init` context stack (pending removal of SamplingContext) * Remove SamplingContext from JETExt to avoid triggering `Sampling->Init` pathway * Remove `predict` on vector of VarInfo * Fix some tests * Remove duplicated test * Simplify context testing * Rename FooInit -> InitFromFoo * Fix JETExt * Fix JETExt properly * Fix tests * Improve comments * Remove duplicated tests * Docstring improvements Co-authored-by: Markus Hauru <[email protected]> * Concretise `chain_sample_to_varname_dict` using chain value type * Clarify testset name * Re-add comment that shouldn't have vanished * Fix stale Requires dep * Fix default_varinfo/initialisation for odd models * Add comment to src/sampler.jl Co-authored-by: Markus Hauru <[email protected]> --------- Co-authored-by: Markus Hauru <[email protected]> * `InitContext`, part 5 - Remove `SamplingContext`, `SampleFrom{Prior,Uniform}`, `{tilde_,}assume` (#985) * Remove `SamplingContext` for good * Remove `tilde_assume` as well * Split up tilde_observe!! for Distribution / Submodel * Tidy up tilde-pipeline methods and docstrings * Fix tests * fix ambiguity * Add changelog * Update HISTORY.md Co-authored-by: Markus Hauru <[email protected]> --------- Co-authored-by: Markus Hauru <[email protected]> * fix missing import * Shuffle context code around and remove dead code (#1050) * Delete the `"del"` flag (#1058) * Delete del * Fix a typo * Add HISTORY entry about del * Fixes for Turing 0.41 (#1057) * setleafcontext(model, ctx) and various other fixes * fix a bug * Add warning for `initial_parameters=...` * Remove `resume_from` and `default_chain_type` (#1061) * Remove resume_from * Format * Fix test * remove initial_params warning * Allow more flexible `initial_params` (#1064) * Enable NamedTuple/Dict initialisation * Add more tests * fix include_all kwarg for predict, improve perf (#1068) * Fix `include_all` for predict * Fix include_all for predict, some perf improvements * Replace `Metadata.flags` with `Metadata.trans` (#1060) * Replace Medata.flags with Metadata.trans * Fix a bug * Fix a typo * Fix two bugs * Rename trans to is_transformed * Rename islinked to is_transformed, remove duplication * Change pointwise_logdensities default key type to VarName (#1071) * Change pointwise_logdensities default key type to VarName * Fix a doctest * Fix DynamicPPL / MCMCChains methods (#1076) * Reimplement pointwise_logdensities (almost completely) * Move logjoint, logprior, ... as well * Fix imports, etc * Remove tests that are failing (yes I learnt this from Claude) * Changelog * logpdf * fix docstrings * allow dict output * changelog * fix some comments * fix tests * Fix more imports * Remove stray n Co-authored-by: Markus Hauru <[email protected]> * Expand `logprior`, `loglikelihood`, and `logjoint` docstrings --------- Co-authored-by: Markus Hauru <[email protected]> * Remove `Sampler` and its interface (#1037) * Remove `Sampler` and `initialstep` * Actually just remove the entire file * forgot one function * Move sampling test utils to Turing as well * Update changelog to correctly reflect changes * [skip ci] Make changelog headings more consistent --------- Co-authored-by: Markus Hauru <[email protected]>

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penelopeysm changed the title ~~InitContext, part 5 - Remove SamplingContext, SampleFromPrior, SampleFromUniform, and associated code~~ InitContext, part 5 - Remove SamplingContext, SampleFrom{Prior,Uniform}, {tilde_,}assume Jul 10, 2025

This was referenced Jul 10, 2025

The big InitContext PR. Do not merge! #967

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Release v0.37 #901

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This was referenced Jul 29, 2025

Test against Enzyme TuringLang/Turing.jl#2636

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Change default Metadata value type to Any #1003

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InitContext, part 4 - Use init!! to replace evaluate_and_sample!!, predict, returned, and initialize_values #984

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Allowing resume_from to grab the previous state #1034

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penelopeysm added 3 commits September 18, 2025 12:19

Remove SamplingContext for good

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Remove tilde_assume as well

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Split up tilde_observe!! for Distribution / Submodel

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Tidy up tilde-pipeline methods and docstrings

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fix ambiguity

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Co-authored-by: Markus Hauru <[email protected]>

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SampleFromPrior, etc. cleanup #859

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InitContext, part 5 - Remove SamplingContext, SampleFrom{Prior,Uniform}, {tilde_,}assume #985

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`InitContext`, part 5 - Remove `SamplingContext`, `SampleFrom{Prior,Uniform}`, `{tilde_,}assume` #985

`InitContext`, part 5 - Remove `SamplingContext`, `SampleFrom{Prior,Uniform}`, `{tilde_,}assume` #985

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