let's try with DynamicPPLAny

Author: penelopeysm

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(