funcprog: Minor improvements.

funcprog/week3/ass7.ml

@@ -54,7 +54,10 @@ print "7.5: %b\n" ((=) (reduce (+) 0 [1;2;3;4;5]) 15);;
 
 (* 6: isSublist l s that checks whether or not the argument list s is a sublist
  * of the argument list l. *)
-let rec isSublist l s = match (l, s) with
+let isSublist l s = 
+    (* Store the full search term *)
+    let full = s in
+    let rec sublistMatches l s = match (l, s) with
     | _, [] -> true
     | [], _ -> false
     | h1::t1, h2::t2 -> 
@@ -63,14 +66,17 @@ let rec isSublist l s = match (l, s) with
         (* and the next head of s matches the next head of l. *)
         && ( t1 = [] && t2 = [] || hd t1 = hd t2 )
         (* recursively match the tails of s and l. *)
-        && isSublist t1 t2
-        (* otherwise, continue with the tail of s. *)
-        || isSublist t1 s
+        && sublistMatches t1 t2
+        (* otherwise, continue with the tail of l and reset s. *)
+        || sublistMatches t1 full
+    in sublistMatches l s
 ;;
 
 print "7.6.1: %b\n" (isSublist [1;2;3;4] [3;4]);;
 print "7.6.2: %b (%s)\n" (isSublist [1;2;3;4] [2;4]) "expected failure";;
-print "7.6.3: %b\n" (isSublist [] []);;
+print "7.6.3: %b (%s)\n" (isSublist [1;2;3;3;4] [2;3;4]) "expected failure";;
+print "7.6.4: %b\n" (isSublist [1;2;3;3;4] [3;3;4]);;
+print "7.6.5: %b\n" (isSublist [] []);;
 
 (* 7. lookup l key that given a list l of (key, value) tuples and a key returns
  * the value associated with that key. *)