(.module:
  [lux #*
   [data
    [text ("text/." Equivalence<Text>)]]])

(type: #export (PList a)
  (List [Text a]))

(def: #export (get key properties)
  (All [a] (-> Text (PList a) (Maybe a)))
  (case properties
    #.Nil
    #.None

    (#.Cons [k' v'] properties')
    (if (text/= key k')
      (#.Some v')
      (get key properties'))))

(def: #export (contains? key properties)
  (All [a] (-> Text (PList a) Bit))
  (case (get key properties)
    (#.Some _)
    #1

    #.None
    #0))

(def: #export (put key val properties)
  (All [a] (-> Text a (PList a) (PList a)))
  (case properties
    #.Nil
    (list [key val])

    (#.Cons [k' v'] properties')
    (if (text/= key k')
      (#.Cons [key val]
              properties')
      (#.Cons [k' v']
              (put key val properties')))))

(def: #export (update key f properties)
  (All [a] (-> Text (-> a a) (PList a) (PList a)))
  (case properties
    #.Nil
    #.Nil

    (#.Cons [k' v'] properties')
    (if (text/= key k')
      (#.Cons [k' (f v')] properties')
      (#.Cons [k' v'] (update key f properties')))))

(def: #export (remove key properties)
  (All [a] (-> Text (PList a) (PList a)))
  (case properties
    #.Nil
    properties

    (#.Cons [k' v'] properties')
    (if (text/= key k')
      properties'
      (#.Cons [k' v']
              (remove key properties')))))