[r2003-11-26 20:08:23 by beppe] programmed count in tail recursive way

Original author: beppe
Date: 2003-11-26 20:08:23+00:00

tests/cql/q6.cd

 (*********function *********)
-let fun count([Any*]->Int)
+let fun count_bad([Any*]->Int)
 	  [] -> 0
 	| [_;t] -> 1+count(t);;
 
+(* tail recursive definition *)
+
+let fun count(x : [Any*]) : Int =
+  let tr_count((Int,[Any*]) -> Int)
+        |  (n,[]) -> n
+        |  (n,[_;t]) -> tr_count(n+1,t)
+   in tr_count(0,x)
+
 (***************************)
 
 (*****************************************************************