9mm/lib/table.fnl

;; table funs

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

(fn head [t] 
  "return the first item in a table"
  (if (> (length t) 0)
   (?. t 1)
   []))

(fn tail [t]
  "return the table minus the head"
  (icollect [i v (ipairs t)]
            (if (> i 1)
              v)))

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

(fn flip [t]
  "takes a table of {key value} and returns a table of {value key}"
  (collect [k v (pairs t)] (values v k)))

(fn print [tbl]
  "print a table"
  (each [k v (pairs tbl)]
    (let [table? (= (type v) :table)]
      (print k v))))

(fn slice [t start stop]
  "return a slice of a table"
  (fcollect [i start (or stop (length t))]
    (. t i)))

{
 : contains
 : flip
 : head
 : keys
 : print
 : slice
 : tail
 }