(fn contains? [t x]
  "does sequence t contain element x?"
  (accumulate [found false
               _ v (ipairs t)
               &until found] ; escape early
    (or found (= x v))))

(fn keys [t]
  "takes a table returns a sequential list of its keys"
  (local out [])
  (each [k _ (pairs t)] (table.insert out k))
  out)

(fn has-key? [t k]
  (contains? (keys t) k))

{: contains?
 : keys
 : has-key?
 }