diff --git a/runtime/Std.i b/runtime/Std.i
index f8e6aceeb..bfdd6bc9f 100644
--- a/runtime/Std.i
+++ b/runtime/Std.i
@@ -4,6 +4,7 @@ F,hd;
 F,tl;
 F,readLine;
 F,stringcat;
+F,matchSubString;
 F,sprintf;
 F,makeString;
 F,printf;
diff --git a/runtime/runtime.c b/runtime/runtime.c
index d75b8fdad..be3a150f0 100644
--- a/runtime/runtime.c
+++ b/runtime/runtime.c
@@ -288,6 +288,13 @@ static void stringcat (void *p) {
   }
 }
 
+extern int LmatchSubString (char *subj, char *patt, int pos) {
+  data *p = TO_DATA(patt);
+  int   n = LEN (p->tag);
+
+  return BOX(strncmp (subj + UNBOX(pos), patt, n) == 0);
+}
+
 extern int Lcompare (void *p, void *q) {
 # define COMPARE_AND_RETURN(x,y) do if (x != y) return BOX(x - y); while (0)
   if (UNBOXED(p)) {
diff --git a/src/Language.ml b/src/Language.ml
index c57fc625f..651880e7f 100644
--- a/src/Language.ml
+++ b/src/Language.ml
@@ -11,8 +11,6 @@ open Combinators
 
 exception Semantic_error of string
 
-let unquote s = String.sub s 1 (String.length s - 2)
-
 module Loc =
   struct
     @type t = int * int with show, html
@@ -279,7 +277,7 @@ module Pattern =
                                                      }
       | x:LIDENT y:(-"@" parse)?                     {match y with None -> Named (x, Wildcard) | Some y -> Named (x, y)}
       | s:("-")? c:DECIMAL                           {Const (match s with None -> c | _ -> ~-c)}
-      | s:STRING                                     {String (unquote s)}
+      | s:STRING                                     {String s}
       | c:CHAR                                       {Const  (Char.code c)}
       | %"true"                                      {Const 1}
       | %"false"                                     {Const 0}
@@ -689,12 +687,12 @@ module Expr =
         | base[def][infix][atr];
       base[def][infix][atr]:
         n:DECIMAL                                 => {notRef atr} => {ignore atr (Const n)}
-      | s:STRING                                  => {notRef atr} => {ignore atr (String (unquote s))}
+      | s:STRING                                  => {notRef atr} => {ignore atr (String s)}
       | c:CHAR                                    => {notRef atr} => {ignore atr (Const  (Char.code c))}
       
       | c:(%"true" {Const 1} | %"false" {Const 0}) => {notRef atr} => {ignore atr c} 
        
-      | %"infix" s:STRING                         => {notRef atr} => {ignore atr (Var (infix_name @@ unquote s))}
+      | %"infix" s:STRING                         => {notRef atr} => {ignore atr (Var (infix_name s))}
       | %"fun" "(" args:!(Util.list0)[ostap (LIDENT)] ")" body:basic[def][infix][Void]  => {notRef atr} => {ignore atr (Lambda (args, body))}
       | "[" es:!(Util.list0)[parse def infix Val] "]" => {notRef atr} => {ignore atr (Array es)}
       | -"{" scope[def][infix][atr][parse def] -"}" 
@@ -855,12 +853,12 @@ module Definition =
     ostap (
       arg : LIDENT;      
       position[pub][ass][coord][newp]:
-        %"at" s:STRING {match ass with `Nona -> Infix.at coord (unquote s) newp pub | _ -> raise (Semantic_error (Printf.sprintf "associativity for infxi '%s' can not be specified (it is inherited from that for '%s')" newp s))}
-        | f:(%"before" {Infix.before} | %"after" {Infix.after}) s:STRING {f coord (unquote s) newp ass pub};
+        %"at" s:STRING {match ass with `Nona -> Infix.at coord s newp pub | _ -> raise (Semantic_error (Printf.sprintf "associativity for infxi '%s' can not be specified (it is inherited from that for '%s')" newp s))}
+        | f:(%"before" {Infix.before} | %"after" {Infix.after}) s:STRING {f coord s newp ass pub};
       head[infix]:
         m:(%"external" {`Extern} | %"public" e:(%"external")? {match e with None -> `Public | _ -> `PublicExtern})? %"fun" name:LIDENT {unopt_mod m, name, name, infix}
     |   m:(%"public" {`Public})? ass:(%"infix" {`Nona} | %"infixl" {`Lefta} | %"infixr" {`Righta})
-        l:$ op:(s:STRING {unquote s})
+        l:$ op:(s:STRING {s})
         md:position[match m with Some _ -> true | _ -> false][ass][l#coord][op] {
           let name = Expr.infix_name op in
           match md (Expr.sem name) infix with
@@ -993,9 +991,9 @@ ostap (
                  | `Fail msg  -> raise (Semantic_error msg)
                in
                match item with
-               | `Infix (_  , op, `At     op') -> insert (unquote op) infix (Infix.at l#coord (unquote op') (unquote op) false)
-               | `Infix (ass, op, `Before op') -> insert (unquote op) infix (Infix.before l#coord (unquote op') (unquote op) ass false)
-               | `Infix (ass, op, `After  op') -> insert (unquote op) infix (Infix.after l#coord (unquote op') (unquote op) ass false)
+               | `Infix (_  , op, `At     op') -> insert op infix (Infix.at l#coord op' op false)
+               | `Infix (ass, op, `Before op') -> insert op infix (Infix.before l#coord op' op ass false)
+               | `Infix (ass, op, `After  op') -> insert op infix (Infix.after l#coord op' op ass false)
                | _                             -> infix
             )
             infix
diff --git a/src/X86.ml b/src/X86.ml
index 4f94ec777..ce6763762 100644
--- a/src/X86.ml
+++ b/src/X86.ml
@@ -583,6 +583,21 @@ class env prg =
 
     (* registers a string constant *)
     method string x =
+      let escape x =
+        let n   = String.length x     in
+        let buf = Buffer.create (n*2) in
+        let rec iterate i =
+          if i < n
+          then (
+            if x.[i] = '"' then Buffer.add_string buf "\\\""
+            else Buffer.add_char buf x.[i];
+            iterate (i+1)
+          )
+        in
+        iterate 0;
+        Buffer.contents buf
+      in
+      let x = escape x in
       try M.find x stringm, self
       with Not_found ->
         let y = Printf.sprintf "string_%d" scount in
diff --git a/stdlib/Matcher.expr b/stdlib/Matcher.expr
new file mode 100644
index 000000000..291f06531
--- /dev/null
+++ b/stdlib/Matcher.expr
@@ -0,0 +1,60 @@
+-- Matcher library for Ostap
+
+fun matcherCreate (pos, buf, line, col) {
+  fun show () {
+    return sprintf ("buf : %-40s\npos : %d\nline: %d\ncol : %d\n", buf, pos, line, col)
+  }
+  
+  fun rest () {
+    return buf.length - pos
+  }
+  
+  fun shift (n) {
+    return matcherCreate (pos + n, buf, line, col + n)
+  }
+  
+  fun matchString (s) {
+    return
+      if s.length > rest ()
+      then None
+      elif matchSubString (buf, s, pos) then Some (shift (s.length)) 
+      else None
+      fi
+  }
+
+  fun eof () {
+    return rest () == 0
+  }
+  
+  return [
+     show,
+     eof,
+     matchString
+  ]
+}
+
+fun show (m) {
+  return m [0]
+}
+
+fun eof (m) {
+  return m [1]
+}
+
+fun matchString (m, s) {
+  return m [2] (s)
+}
+
+fun matcherInit (buf) {
+  return matcherCreate (0, buf, 1, 1)
+}
+
+local m = matcherInit ("abc");
+
+printf ("%s", m.show ());
+printf ("eof: %s\n", m.eof ().string);
+printf ("matchString(""u""): %s\n", case m.matchString ("u") of Some (m) -> m.show () | _ -> "None" esac);
+printf ("matchString(""a""): %s\n", case m.matchString ("a") of Some (m) -> m.show () | _ -> "None" esac);
+printf ("matchString(""ab""): %s\n", case m.matchString ("ab") of Some (m) -> m.show () | _ -> "None" esac);
+printf ("matchString(""abc""): %s\n", case m.matchString ("abc") of Some (m) -> m.show () | _ -> "None" esac);
+printf ("matchString(""abcd""): %s\n", case m.matchString ("abcd") of Some (m) -> m.show () | _ -> "None" esac)
\ No newline at end of file