a1/mart/skeleton1.icl

   1 module skeleton1
   2
   3 /*
   4         Course I00032 Advanced Programming 2014
   5         Skeleton for assignment 1
   6         Pieter Koopman
   7 */
   8
   9 import StdEnv
  10
  11 /**************** Prelude: *******************************/
  12 //      Example types
  13 :: Color        = Red | Yellow | Blue
  14 :: Tree a       = Tip | Bin a (Tree a) (Tree a)
  15 :: Rose a       = Rose a [Rose a]
  16
  17 //      Binary sums and products (in generic prelude)
  18 :: UNIT                 = UNIT
  19 :: PAIR   a b   = PAIR a b
  20 :: EITHER a b   = LEFT a | RIGHT b
  21
  22 //      Generic type representations
  23 :: RoseG a      :== PAIR a [Rose a]
  24
  25 // Conversions
  26 fromRose :: (Rose a)    -> RoseG a
  27 fromRose (Rose a l)             = PAIR a l
  28
  29 // Oerdering
  30
  31 ::      Ordering = Smaller | Equal | Bigger
  32
  33 class (><) infix 4 a :: !a !a -> Ordering
  34
  35 instance >< Int where           // Standard ordering for Int
  36         (><) x y
  37         | x < y         = Smaller
  38         | x > y         = Bigger
  39         | otherwise     = Equal
  40
  41 instance >< Char where          // Standard ordering for Char
  42         (><) x y
  43         | x < y         = Smaller
  44         | x > y         = Bigger
  45         | otherwise     = Equal
  46
  47 instance >< String where        // Standard lexicographical ordering
  48         (><) x y
  49         | x < y         = Smaller
  50         | x > y         = Bigger
  51         | otherwise     = Equal
  52
  53 instance >< Bool where          // False is smaller than True
  54         (><) False True  = Smaller
  55         (><) True  False = Bigger
  56         (><) _     _     = Equal
  57
  58 /**************** End Prelude *************************/