fp2/week3/camil/StdDynSet.icl

   1 implementation module StdDynSet
   2
   3 import StdEnv
   4 import StdMaybe
   5 import StdDynamic
   6
   7 fromDynamic :: Dynamic -> Maybe t | TC t
   8 fromDynamic (x :: t^) = Just x
   9 fromDynamic other = Nothing
  10
  11 isEqual:: Dynamic t -> Bool | Set t
  12 isEqual (x :: t^) a = x == a
  13 isEqual _ _ = False
  14
  15 class Set a | TC, ==, toString a
  16
  17 :: Set = Set [Dynamic]
  18
  19 instance zero     Set
  20 where zero = Set []
  21
  22 instance toString Set
  23 where toString (Set a) = abort "toString not implemented"
  24
  25 instance == Set
  26 where == a b = nrOfElts a == nrOfElts b && isSubset a b
  27
  28 toSet :: a -> Set | Set, == a
  29 toSet e = Set [dynamic e]
  30
  31 nrOfElts :: Set -> Int
  32 nrOfElts (Set a) = length a
  33
  34 isEmptySet :: Set -> Bool
  35 isEmptySet (Set []) = True
  36 isEmptySet _ = False
  37
  38 memberOfSet :: a Set -> Bool | Set, == a
  39 memberOfSet _ (Set []) = False
  40 memberOfSet x (Set [(y :: a^):xs]) = x == y || memberOfSet x (Set xs)
  41 memberOfSet x (Set [y:xs]) = memberOfSet x (Set xs)
  42
  43 dynMemberOfSet :: Dynamic Set -> Bool
  44 dynMemberOfSet _ (Set []) = False
  45 dynMemberOfSet x (Set [y:xs]) = isEqual x (fromJust(fromDynamic y)) || dynMemberOfSet x (Set xs)
  46 //dynMemberOfSet x (Set [y:xs]) = memberOfSet x (Set xs)
  47
  48 isSubset :: Set Set -> Bool
  49 isSubset a b = (nrOfElts a) == (nrOfElts (intersection a b))
  50
  51 isStrictSubset :: Set Set -> Bool
  52 isStrictSubset a b = abort "isStrictSubset nog niet geimplementeerd.\n"
  53
  54 union :: Set Set -> Set
  55 union (Set a) (Set b) = Set (a ++ b)
  56
  57 intersection :: Set Set -> Set
  58 intersection (Set []) bs = bs
  59 intersection as (Set []) = as
  60 intersection (Set [a:as]) (Set [(b::t):bs]) = Set [a \\ a <- as | not (dynMemberOfSet a (Set bs))]
  61
  62 without :: Set Set -> Set
  63 without a b = abort "without nog niet geimplementeerd.\n"
  64
  65 //Start :: Set
  66 Start = memberOfSet 2 (toSet 1)