From 9698d7b82f33b9d2b7ba7f3d22a194c1a2fc258c Mon Sep 17 00:00:00 2001
From: Penelope Yong <penelopeysm@gmail.com>
Date: Mon, 1 Sep 2025 13:26:02 +0100
Subject: [PATCH 1/2] Bump minor version

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 422284095..32bf85cec 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "Turing"
 uuid = "fce5fe82-541a-59a6-adf8-730c64b5f9a0"
-version = "0.40.2"
+version = "0.41.0"
 
 [deps]
 ADTypes = "47edcb42-4c32-4615-8424-f2b9edc5f35b"

From ec8f1655b736686504aa3766f86d6bab66e8fc84 Mon Sep 17 00:00:00 2001
From: Penelope Yong <penelopeysm@gmail.com>
Date: Thu, 7 Aug 2025 12:53:44 +0100
Subject: [PATCH 2/2] Use typed VarInfo for Prior sampler

---
 src/mcmc/prior.jl | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/mcmc/prior.jl b/src/mcmc/prior.jl
index 2ead40ced..7ef75024d 100644
--- a/src/mcmc/prior.jl
+++ b/src/mcmc/prior.jl
@@ -26,5 +26,36 @@ function AbstractMCMC.step(
         ),
     )
     _, vi = DynamicPPL.evaluate!!(sampling_model, vi)
-    return Transition(model, vi, nothing; reevaluate=false), nothing
+    vi = DynamicPPL.typed_varinfo(vi)
+    return Transition(model, vi, nothing; reevaluate=false), vi
+end
+
+function AbstractMCMC.step(
+    rng::Random.AbstractRNG,
+    model::DynamicPPL.Model,
+    sampler::DynamicPPL.Sampler{<:Prior},
+    vi::AbstractVarInfo;
+    kwargs...,
+)
+    # TODO(DPPL0.38/penelopeysm): replace this entire thing with init!!
+    #
+    # `vi` is a VarInfo from the previous step so already has all the
+    # right accumulators and stuff. The only thing we need to change is to make
+    # sure that the old values are overwritten when we resample.
+    #
+    # Note also that the values in the Transition (and hence the chain) are not
+    # obtained from the VarInfo's metadata itself, but are instead obtained
+    # from the ValuesAsInModelAccumulator, which is cleared in the evaluate!!
+    # call. Thus, the actual values in the VarInfo's metadata don't matter:
+    # we only set the del flag here to make sure that new values are sampled
+    # (and thus new values enter VAIMAcc), rather than the old ones being
+    # reused during the evaluation. Yes, SampleFromPrior really sucks.
+    for vn in keys(vi)
+        DynamicPPL.set_flag!(vi, vn, "del")
+    end
+    sampling_model = DynamicPPL.contextualize(
+        model, DynamicPPL.SamplingContext(rng, DynamicPPL.SampleFromPrior(), model.context)
+    )
+    _, vi = DynamicPPL.evaluate!!(sampling_model, vi)
+    return Transition(model, vi, nothing; reevaluate=false), vi
 end