# 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

```ocaml
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))
```