Remove unneeded type param from PrefixContext

Author: penelopeysm

src/contexts.jl

@@ -265,8 +265,8 @@ end
 
 Apply the prefixes in the context `ctx` to the variable name `vn`.
 """
-function prefix(ctx::PrefixContext{Prefix}, vn::VarName{Sym}) where {Prefix,Sym}
-    return AbstractPPL.prefix(prefix(childcontext(ctx), vn), VarName{Symbol(Prefix)}())
+function prefix(ctx::PrefixContext{Prefix}, vn::VarName) where {Prefix}
+    return AbstractPPL.prefix(prefix(childcontext(ctx), vn), VarName{Prefix}())
 end
 function prefix(ctx::AbstractContext, vn::VarName)
     return prefix(NodeTrait(ctx), ctx, vn)

src/utils.jl

@@ -1286,7 +1286,9 @@ broadcast_safe(x::Distribution) = (x,)
 broadcast_safe(x::AbstractContext) = (x,)
 
 # Convert (x=1,) to Dict(@varname(x) => 1)
-to_varname_dict(nt::NamedTuple) = Dict(VarName{k}() => v for (k, v) in pairs(nt))
+function to_varname_dict(nt::NamedTuple)
+    return Dict{VarName,Any}(VarName{k}() => v for (k, v) in pairs(nt))
+end
 to_varname_dict(d::AbstractDict) = d
 # Version of `merge` used by `conditioned` and `fixed` to handle
 # the scenario where we might try to merge a dict with an empty