(.module:
  [lux #*]
  [//
   ["." order (#+ Order)]])

(signature: #export (Enum e)
  {#.doc "Enumerable types, with a notion of moving forward and backwards through a type's instances."}
  (: (Order e) &order)
  (: (-> e e) succ)
  (: (-> e e) pred))

(def: (range' <= succ from to)
  (All [a] (-> (-> a a Bit) (-> a a) a a (List a)))
  (if (<= to from)
    (#.Cons from (range' <= succ (succ from) to))
    #.Nil))

(def: #export (range (^open ",@.") from to)
  {#.doc "An inclusive [from, to] range of values."}
  (All [a] (-> (Enum a) a a (List a)))
  (range' (order.<= ,@&order) ,@succ from to))