--- a/src/HOL/ex/Qsort.thy Mon Mar 27 16:25:53 2000 +0200
+++ b/src/HOL/ex/Qsort.thy Mon Mar 27 17:04:03 2000 +0200
@@ -7,6 +7,8 @@
*)
Qsort = Sorting +
+
+(*Version one: higher-order*)
consts qsort :: "((['a,'a] => bool) * 'a list) => 'a list"
recdef qsort "measure (size o snd)"
@@ -17,4 +19,15 @@
"qsort(le, x#xs) = qsort(le, [y:xs . ~ le x y])
@ (x # qsort(le, [y:xs . le x y]))"
+
+(*Version two: type classes*)
+consts quickSort :: "('a::linorder) list => 'a list"
+
+recdef quickSort "measure size"
+ simpset "simpset() addsimps [length_filter RS le_less_trans]"
+
+ "quickSort [] = []"
+
+ "quickSort (x#l) = quickSort [y:l. ~ x<=y] @ (x # quickSort [y:l. x<=y])"
+
end