A year <select>, a port of calendar-year-month/calendar-select-year.tsx.

It is a child of a picker, so it goes where any other child goes. Cally puts it in the heading slot:

Cally.Date.view { config | heading = Just heading } value model
    [ Cally.Month.view { offset = 0 } ]


heading context =
    Html.div []
        [ Cally.SelectYear.view { maxYears = 20 } context
        , Cally.SelectMonth.view { formatMonth = Cally.Locale.MonthLong } context
        ]