delta

OCaml compiler for a small pure functional language of keyed collection queries

Collections are unordered finite maps from signed machine integers to values. map preserves keys; filter keeps the keys of the rows it retains. Results are printed in key order, so presentation is deterministic

Language

type order = {
  customer : string;
  total : int;
}

input orders : collection order

let tax n = n * 20 / 100

query expensive_orders =
  orders
  |> filter (fun o -> o.total > 1000)
  |> map (fun o -> (o.customer, tax o.total))