Suggestion: relax type annotation on `dict2columns`

[kpa28-git]

I like using StructArrays.jl for data manipulation. Converting a StructVector to a NamedTuple is basically free because of how StructArray is implemented. There are a number of Tables.jl types that work like this.

I wonder if we could relax the data input type annotation on dict2columns? This would allow us to insert iterators of anything that validly implements Base.keys and Base.pairs (e.g. NamedTuple).

I tried this change to src/Query.jl and it doesn't break any existing test cases:

function dict2columns(
-    dict::Dict{Symbol, T} where T,
+    dict,
    valid_columns::Dict{Symbol, String},
)::Vector{Column}

...

      [
          Column(string(name), valid_columns[name], column)
-        for (name, column) ∈ dict
+        for (name, column) ∈ pairs(dict)
      ]
end

Maybe a simple stopgap until Tables.jl integration.