diff --git a/lama-spec.pdf b/lama-spec.pdf
index 4578a8b31..372dbaef1 100644
Binary files a/lama-spec.pdf and b/lama-spec.pdf differ
diff --git a/spec/06.standard_library.tex b/spec/06.standard_library.tex
index bf19d8e86..896ca1d81 100644
--- a/spec/06.standard_library.tex
+++ b/spec/06.standard_library.tex
@@ -333,7 +333,8 @@ The unit describes some primitive parsers and combinators which allow to constru
 
 \descr{\lstinline|fun memo (f)|}{Takes a parser "\lstinline|a|" and returns its memoized version. Needed for some parsers (for expamle, left-recursive ones).}
 
-\descr{\lstinline|fun token (x)|}{Takes a string and returns a parser which recognizes exactly this string.}
+\descr{\lstinline|fun token (x)|}{Takes a string or a representation of regular expression, returned by "\lstinline|createRegexp|" (see unit \texttt{Matcher}),
+  and returns a parser which recognizes exactly this string/regular expression.}
 
 \descr{\lstinline|fun eof (k)|}{A parser which recognizes the end of stream.}
 
diff --git a/src/version.ml b/src/version.ml
index e6770824f..5483d03b6 100644
--- a/src/version.ml
+++ b/src/version.ml
@@ -1 +1 @@
-let version = "Version 1.00, a44ccbf2, Fri Feb 28 01:11:40 2020 +0300"
+let version = "Version 1.00, 50fc2e9f, Fri Feb 28 18:32:19 2020 +0300"
diff --git a/stdlib/Matcher.lama b/stdlib/Matcher.lama
index bc04acc9d..ce7f48cbb 100644
--- a/stdlib/Matcher.lama
+++ b/stdlib/Matcher.lama
@@ -55,7 +55,7 @@ fun createMatcher (buf, pos, line, col) {
   fun matchRegexp (r) {
     local n;
     
-    if (n := regexpMatch (r[0], buf, pos)) > 0
+    if (n := regexpMatch (r[0], buf, pos)) >= 0
     then Succ (substring (buf, pos, n), shift (n))
     else Fail (sprintf ("%s expected", r[1]), line, col)
     fi
diff --git a/stdlib/Ostap.lama b/stdlib/Ostap.lama
index db0c38e9c..845b14b35 100644
--- a/stdlib/Ostap.lama
+++ b/stdlib/Ostap.lama
@@ -64,11 +64,10 @@ public fun memo (f) {
 }
 
 public fun token (x) {
-  fun (k) {
-    fun (s) {
-      k $ matchString (s, x)
-    }
-  }   
+  case x of
+    #string -> fun (k) {fun (s) {k $ matchString (s, x)}}
+  | _       -> fun (k) {fun (s) {k $ matchRegexp (s, x)}}
+  esac
 }
 
 public fun eof (k) {
@@ -130,8 +129,8 @@ public fun bypass (f) {
 public fun opt (a) {empty @ lift (None) | a @ fun (x) {Some (x)}}
 
 public fun rep0 (a) {
-  --memo
-  (empty @ lift({}) | a |> fun (x) {rep0 (a) @ fun (as) {x : as}})
+  memo
+    (empty @ lift({}) | a |> fun (x) {rep0 (a) @ fun (as) {x : as}})
 }
 
 public fun rep (a) {
diff --git a/tutorial/Expressions.lama b/tutorial/Expressions.lama
index 78c75f2de..6fb4a8040 100644
--- a/tutorial/Expressions.lama
+++ b/tutorial/Expressions.lama
@@ -2,8 +2,8 @@ printf ("if, case, for, while, repeat etc. are all expressions.\n");
 
 printf ("Case-expression: %s\n", case A (1, 2, 3) of A (x, y, z) -> z esac.string);
 
-printf ("If-expression: %s\n", if true then 2 else 3 fi +
-                               if false then 6 else 7 fi.string);
+printf ("If-expression: %s\n", (if true then 2 else 3 fi +
+                               if false then 6 else 7 fi).string);
                                
 printf ("Scope-expression: %s\n", {local i, s = 0;
                                    for i := 0, i < 10, i := i + 1 do