a3/code/Generics/GenEq.icl

   1 implementation module GenEq
   2
   3 import StdGeneric, StdEnv
   4
   5 generic gEq a  :: a a -> Bool
   6 gEq{|Int|}      x y                                                     = x == y
   7 gEq{|Char|} x y                                                         = x == y
   8 gEq{|Bool|} x y                                                         = x == y
   9 gEq{|Real|} x y                                                         = x == y
  10 gEq{|String|} x y                                                       = x == y
  11 gEq{|UNIT|} UNIT UNIT                                           = True
  12 gEq{|PAIR|} fx fy (PAIR x1 y1) (PAIR x2 y2) = fx x1 x2 && fy y1 y2
  13 gEq{|EITHER|} fl fr (LEFT x) (LEFT y)           = fl x y
  14 gEq{|EITHER|} fl fr (RIGHT x) (RIGHT y)         = fr x y
  15 gEq{|EITHER|} fl fr     _ _                             = False
  16 gEq{|CONS|} f (CONS x) (CONS y)                         = f x y
  17 gEq{|FIELD|} f (FIELD x) (FIELD y)                      = f x y
  18 gEq{|OBJECT|} f (OBJECT x) (OBJECT y)           = f x y
  19 gEq{|{}|} f xs ys                                                       = eqArray f xs ys
  20 gEq{|{!}|} f xs ys                                                      = eqArray f xs ys
  21
  22 derive gEq [], (,), (,,), (,,,), (,,,,), (,,,,,), (,,,,,,), (,,,,,,,)
  23
  24
  25 (===) infix 4 :: a a -> Bool | gEq{|*|} a
  26 (===) x y = gEq{|*|} x y
  27
  28 (=!=) infix 4 :: a a -> Bool | gEq{|*|} a
  29 (=!=) x y = not (x === y)
  30
  31 eqArray f xs ys = size xs == size ys && eq 0 (size xs) xs ys
  32 where
  33         eq i n xs ys
  34                 | i == n        = True
  35                 | i < n         = f xs.[i] ys.[i] && eq (inc i) n xs ys