# Operator form for Histogram of multiple datasets?

I would like to plot a histogram for multiple datasets in a dataset query, but can't quite seem to make it work in operator notation:

titanic = ExampleData[{"Dataset", "Titanic"}];
titanic = Dataset@Flatten@Table[
Map[Append[#, "score" -> RandomReal[100]] &, Normal@titanic],
20];

(*this ugly version works:*)
Histogram @ Transpose[List @@@ titanic[Slice[All, {"age", "score"}]] // Normal]

(*but the operator forms version does not:*)
titanic[Histogram, Slice[All, {"age", "score"}]]
titanic[Slice[All, {"age", "score"}] /* Histogram]


How to do this with just operator forms?

• What is the Slice function? – Edmund Sep 12 '18 at 2:24
• It's in GeneralUtilities – M.R. Sep 12 '18 at 2:31
• Also note that Transpose@ titanic[Transpose /* Query[<|#, "score" -> RandomReal[{0, 100}, 1309]|> &]] is a more efficient addition of "score". – Edmund Sep 12 '18 at 2:35
• closely related: How to pass options to ListPlot when using a DataSet? – kglr Sep 12 '18 at 2:36

You may use Composition with Transpose.
titanic[Histogram@*Transpose, {"age", "score"}]