diff --git a/stdlib/Ostap.expr b/stdlib/Ostap.expr
index 77558cea9..ececc4438 100644
--- a/stdlib/Ostap.expr
+++ b/stdlib/Ostap.expr
@@ -11,7 +11,11 @@ public fun initOstap () {
   hct := emptyMemo ()
 }
 
-fun memo (f) {
+public fun cleanupOstap () {
+  initOstap ()
+}
+
+public fun memo (f) {
   local t;
 
   f := lookupMemo (hct, f);
@@ -148,7 +152,7 @@ public fun observe (name, f) {
   }
 }
 
-public fun createResult () {
+fun createResult () {
   local errors   = ref ({}),
         line     = ref (0),
         col      = ref (0),
@@ -192,10 +196,26 @@ public fun createResult () {
   [k, get]
 }
 
-public fun k (acc) {
+fun k (acc) {
   acc [0]
 }
 
-public fun result (acc) {
+fun result (acc) {
   acc [1] ()
 }
+
+public fun parse (p, m) {
+  local acc = createResult ();
+
+  p (acc.k) (m);
+
+  acc.result
+}
+
+public fun parseString (p, s) {
+  local acc = createResult ();
+
+  p (acc.k) (initMatcher (s));
+
+  acc.result
+}
\ No newline at end of file
diff --git a/stdlib/regression/orig/test10.log b/stdlib/regression/orig/test10.log
new file mode 100644
index 000000000..149d3b197
--- /dev/null
+++ b/stdlib/regression/orig/test10.log
@@ -0,0 +1,2 @@
+Parsing "aaa" with many ... Succ ({"a", "a", "a"})
+Parsing "ab" with bad_alter ... Succ ("ab")
diff --git a/stdlib/regression/test10.expr b/stdlib/regression/test10.expr
new file mode 100644
index 000000000..7e46a77fd
--- /dev/null
+++ b/stdlib/regression/test10.expr
@@ -0,0 +1,19 @@
+import Ostap;
+import List;
+import Fun;
+
+fun many (a) {
+  memo (
+   fun (k) {
+      empty @ lift({})
+    | many (a) |> fun (as) {a @ fun (x) {as +++ singleton (x)}} $ k
+   }
+  )
+}
+
+local a = token ("a"), b = token ("b");
+local bad_alter = a | a |> fun (x) {b @ fun (y) {x ++ y}}; 
+
+initOstap ();
+printf ("Parsing ""aaa"" with many ... %s\n", parseString (many (a) |> bypass (eof), "aaa").string);
+printf ("Parsing ""ab"" with bad_alter ... %s\n", parseString (bad_alter |> bypass (eof), "ab").string)
\ No newline at end of file