reset a3, kut Charlie ;)

[tt2015.git] / a3 / code / Generics / GenLexOrd.icl

diff --git a/a3/code/Generics/GenLexOrd.icl b/a3/code/Generics/GenLexOrd.icl
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+++ b/a3/code/Generics/GenLexOrd.icl
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+implementation module GenLexOrd\r
+\r
+import StdEnv\r
+import StdGeneric, GenEq\r
+\r
+:: LexOrd = LT |EQ | GT\r
+derive gEq LexOrd\r
+\r
+generic gLexOrd a b :: a b -> LexOrd\r
+gLexOrd{|Int|} x y\r
+       | x == y = EQ\r
+       | x < y  = LT\r
+                        = GT\r
+gLexOrd{|Bool|} True True = EQ\r
+gLexOrd{|Bool|} False True = LT\r
+gLexOrd{|Bool|} True False = GT\r
+gLexOrd{|Bool|} False False = EQ\r
+gLexOrd{|Real|} x y\r
+       | x == y = EQ\r
+       | x < y  = LT\r
+                        = GT\r
+gLexOrd{|Char|} x y\r
+       | x == y = EQ\r
+       | x < y  = LT\r
+                        = GT\r
+gLexOrd{|String|} x y\r
+       | x == y = EQ\r
+       | x < y  = LT\r
+                        = GT                    \r
+gLexOrd{|UNIT|} UNIT UNIT = EQ\r
+gLexOrd{|PAIR|} fx fy (PAIR x1 y1) (PAIR x2 y2) = case fx x1 x2 of\r
+               EQ -> fy y1 y2\r
+               LT -> LT\r
+               GT -> GT\r
+                       \r
+gLexOrd{|EITHER|} fl fr (LEFT x) (LEFT y) = fl x y \r
+gLexOrd{|EITHER|} fl fr (LEFT x) (RIGHT y) = LT\r
+gLexOrd{|EITHER|} fl fr (RIGHT x) (LEFT y) = GT\r
+gLexOrd{|EITHER|} fl fr (RIGHT x) (RIGHT y) = fr x y\r
+gLexOrd{|CONS|} f (CONS x) (CONS y) = f x y\r
+gLexOrd{|FIELD|} f (FIELD x) (FIELD y) = f x y\r
+gLexOrd{|OBJECT|} f (OBJECT x) (OBJECT y) = f x y\r
+\r
+// Instance on standard lists is needed because\r
+// standard lists have unnatural internal ordering of constructors: Cons < Nil,\r
+// i.e Cons is LEFT and Nil is RIGHT in the generic representation.\r
+// We want ordering Nil < Cons\r
+gLexOrd{|[]|} f [] [] = EQ\r
+gLexOrd{|[]|} f [] _  = LT\r
+gLexOrd{|[]|} f _ []  = GT\r
+gLexOrd{|[]|} f [x:xs] [y:ys] = gLexOrd{|*->*->*|} f (gLexOrd{|*->*|} f) (PAIR x xs) (PAIR y ys)\r
+\r
+gLexOrd{|{}|} f xs ys  = lexOrdArray f xs ys \r
+gLexOrd{|{!}|} f xs ys         = lexOrdArray f xs ys \r
+\r
+\r
+// standard types\r
+derive gLexOrd (,), (,,),  (,,,), (,,,,), (,,,,,), (,,,,,,), (,,,,,,,)\r
+\r
+   \r
+(=?=) infix 4 :: a a -> LexOrd | gLexOrd{|*|} a\r
+(=?=) x y = gLexOrd{|*|} x y                           \r
+\r
+\r
+lexOrdArray f xs ys\r
+       #! size_xs = size xs\r
+       #! size_ys = size ys\r
+       | size_xs < size_ys     = LT\r
+       | size_xs > size_ys = GT\r
+       | otherwise                     = lexord 0 size_xs xs ys\r
+where\r
+       lexord i n xs ys\r
+               | i == n                = EQ\r
+               | otherwise     = case f xs.[i] ys.[i] of\r
+                               LT -> LT\r
+                               GT -> GT        \r
+                               EQ -> lexord (inc i) n xs ys\r