From 8a91ab79deefb717b14d1a1194b17eb7280cb182 Mon Sep 17 00:00:00 2001
From: Penelope Yong <penelopeysm@gmail.com>
Date: Wed, 30 Jul 2025 15:58:58 +0100
Subject: [PATCH 1/2] Change default Metadata value type to Any

---
 src/varinfo.jl | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/varinfo.jl b/src/varinfo.jl
index 07b1869c9..43940685e 100644
--- a/src/varinfo.jl
+++ b/src/varinfo.jl
@@ -37,7 +37,7 @@ struct Metadata{
     TIdcs<:Dict{<:VarName,Int},
     TDists<:AbstractVector{<:Distribution},
     TVN<:AbstractVector{<:VarName},
-    TVal<:AbstractVector{<:Real},
+    TVal<:AbstractVector{<:Any},
 }
     # Mapping from the `VarName` to its integer index in `vns`, `ranges` and `dists`
     idcs::TIdcs # Dict{<:VarName,Int}
@@ -51,7 +51,7 @@ struct Metadata{
 
     # Vector of values of all the univariate, multivariate and matrix variables
     # The value(s) of `vn` is/are `vals[ranges[idcs[vn]]]`
-    vals::TVal # AbstractVector{<:Real}
+    vals::TVal # AbstractVector{<:Any}
 
     # Vector of distributions correpsonding to `vns`
     dists::TDists # AbstractVector{<:Distribution}
@@ -409,7 +409,7 @@ unflatten_metadata(vnv::VarNamedVector, x::AbstractVector) = unflatten(vnv, x)
 Construct an empty type unstable instance of `Metadata`.
 """
 function Metadata()
-    vals = Vector{Real}()
+    vals = Vector{Any}()
     flags = Dict{String,BitVector}()
     flags["del"] = BitVector()
     flags["trans"] = BitVector()
@@ -576,8 +576,8 @@ function merge_metadata(metadata_left::Metadata, metadata_right::Metadata)
     T_right = eltype(metadata_right.vals)
     T = promote_type(T_left, T_right)
     # TODO: Is this necessary?
-    if !(T <: Real)
-        T = Real
+    if !(T <: Any)
+        T = Any
     end
 
     # Determine `eltype` of `dists`.
@@ -767,7 +767,7 @@ function getindex_internal(vi::NTVarInfo, ::Colon)
     return reduce(vcat, map(Base.Fix2(getindex_internal, Colon()), vi.metadata))
 end
 function getindex_internal(vi::VarInfo{NamedTuple{(),Tuple{}}}, ::Colon)
-    return float(Real)[]
+    return Any[]
 end
 function getindex_internal(md::Metadata, ::Colon)
     return mapreduce(

From 2a0fbf2955620f264ff905046c3420b776830cb3 Mon Sep 17 00:00:00 2001
From: Penelope Yong <penelopeysm@gmail.com>
Date: Wed, 30 Jul 2025 16:47:42 +0100
Subject: [PATCH 2/2] let's try with `DynamicPPLAny`

---
 src/varinfo.jl | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/varinfo.jl b/src/varinfo.jl
index 43940685e..cea7cd0c2 100644
--- a/src/varinfo.jl
+++ b/src/varinfo.jl
@@ -6,6 +6,10 @@
 # VarInfo metadata #
 ####################
 
+abstract type DynamicPPLAny end
+Base.convert(::Type{DynamicPPLAny}, x) = x
+Base.zero(::Type{DynamicPPLAny}) = zero(LogProbType)
+
 """
 The `Metadata` struct stores some metadata about the parameters of the model. This helps
 query certain information about a variable, such as its distribution, which samplers
@@ -37,7 +41,7 @@ struct Metadata{
     TIdcs<:Dict{<:VarName,Int},
     TDists<:AbstractVector{<:Distribution},
     TVN<:AbstractVector{<:VarName},
-    TVal<:AbstractVector{<:Any},
+    TVal<:AbstractVector{<:DynamicPPLAny},
 }
     # Mapping from the `VarName` to its integer index in `vns`, `ranges` and `dists`
     idcs::TIdcs # Dict{<:VarName,Int}
@@ -51,7 +55,7 @@ struct Metadata{
 
     # Vector of values of all the univariate, multivariate and matrix variables
     # The value(s) of `vn` is/are `vals[ranges[idcs[vn]]]`
-    vals::TVal # AbstractVector{<:Any}
+    vals::TVal # AbstractVector{<:DynamicPPLAny}
 
     # Vector of distributions correpsonding to `vns`
     dists::TDists # AbstractVector{<:Distribution}
@@ -409,7 +413,7 @@ unflatten_metadata(vnv::VarNamedVector, x::AbstractVector) = unflatten(vnv, x)
 Construct an empty type unstable instance of `Metadata`.
 """
 function Metadata()
-    vals = Vector{Any}()
+    vals = Vector{DynamicPPLAny}()
     flags = Dict{String,BitVector}()
     flags["del"] = BitVector()
     flags["trans"] = BitVector()
@@ -576,8 +580,8 @@ function merge_metadata(metadata_left::Metadata, metadata_right::Metadata)
     T_right = eltype(metadata_right.vals)
     T = promote_type(T_left, T_right)
     # TODO: Is this necessary?
-    if !(T <: Any)
-        T = Any
+    if !(T <: DynamicPPLAny)
+        T = DynamicPPLAny
     end
 
     # Determine `eltype` of `dists`.
@@ -766,8 +770,8 @@ getindex_internal(vi::VarInfo, ::Colon) = getindex_internal(vi.metadata, Colon()
 function getindex_internal(vi::NTVarInfo, ::Colon)
     return reduce(vcat, map(Base.Fix2(getindex_internal, Colon()), vi.metadata))
 end
-function getindex_internal(vi::VarInfo{NamedTuple{(),Tuple{}}}, ::Colon)
-    return Any[]
+function getindex_internal(::VarInfo{NamedTuple{(),Tuple{}}}, ::Colon)
+    return DynamicPPLAny[]
 end
 function getindex_internal(md::Metadata, ::Colon)
     return mapreduce(