diff --git a/Makefile b/Makefile
index 4b162e273..19a6c8037 100644
--- a/Makefile
+++ b/Makefile
@@ -12,4 +12,5 @@ regression:
 
 clean:
 	pushd src && make clean && popd
+	pushd regression && make clean && popd
 
diff --git a/regression/Makefile b/regression/Makefile
index 9759b33e7..8ba71b637 100644
--- a/regression/Makefile
+++ b/regression/Makefile
@@ -9,7 +9,7 @@ BFLAGS = -rectypes -I `ocamlfind -query GT` -I `ocamlfind -query re`  -I `ocamlf
 OFLAGS = $(BFLAGS)
 
 all: .depend $(TOPFILE).opt
-	./$(TOPFILE).opt > $(TOPFILE).log && diff $(TOPFILE).log orig/$(TOPFILE).log 
+	./$(TOPFILE).opt > $(TOPFILE).log && diff -a --strip-trailing-cr $(TOPFILE).log orig/$(TOPFILE).log 
 
 .depend: $(SOURCES)
 	$(OCAMLDEP) $(PXFLAGS) *.ml > .depend
@@ -21,7 +21,7 @@ $(TOPFILE).byte: $(SOURCES:.ml=.cmo)
 	$(OCAMLC) -o $(TOPFILE).byte $(BFLAGS) $(LIBS) ostap.cmo Syntax.cmo Embedding.cmo SM.cmo $(SOURCES:.ml=.cmo) 
 
 clean:
-	rm -Rf *.cmi *.cmo *.cmx *.annot *.o *.opt *.byte *~
+	rm -Rf *.cmi *.cmo *.cmx *.annot *.o *.opt *.byte *~ *.log .depend
 
 -include .depend
 # generic rules
diff --git a/src/Driver.ml b/src/Driver.ml
new file mode 100644
index 000000000..604223660
--- /dev/null
+++ b/src/Driver.ml
@@ -0,0 +1,41 @@
+open Ostap
+
+let parse infile =
+  let s = Util.read infile in
+  Util.parse
+    (object
+       inherit Matcher.t s
+       inherit Util.Lexers.decimal s
+       inherit Util.Lexers.skip [
+	 Matcher.Skip.whitespaces " \t\n";
+	 Matcher.Skip.lineComment "--";
+	 Matcher.Skip.nestedComment "(*" "*)"
+       ] s
+     end
+    )
+    (ostap (!(Language.parse) -EOF))
+
+let main =
+  try
+    let interpret  = Sys.argv.(1) = "-i"  in
+    let stack      = Sys.argv.(1) = "-s"  in
+    let infile     = Sys.argv.(2) in
+    match parse infile with
+    | `Ok ((_, stmt) as prog) ->
+       let rec read acc =
+         try
+	   let r = read_int () in
+	   Printf.printf "> ";
+	   read (acc @ [r]) 
+         with End_of_file -> acc
+       in
+       let input = read [] in	
+       let output = 
+	 if interpret 
+	 then Language.eval prog input 
+	 else SM.eval (SM.compile prog) input
+       in
+       List.iter (fun i -> Printf.printf "%d\n" i) output
+    | `Fail er -> Printf.eprintf "Syntax error: %s\n" er
+  with Invalid_argument _ ->
+    Printf.printf "Usage: rc [-i] <input file.expr>\n"
diff --git a/src/Syntax.ml b/src/Language.ml
similarity index 82%
rename from src/Syntax.ml
rename to src/Language.ml
index b493f2f5f..fa86e046a 100644
--- a/src/Syntax.ml
+++ b/src/Language.ml
@@ -1,8 +1,11 @@
 (* Opening a library for generic programming (https://github.com/dboulytchev/GT).
    The library provides "@type ..." syntax extension and plugins like show, etc.
 *)
-open GT 
-    
+open GT
+
+(* Opening a library for combinator-based syntax analysis *)
+open Ostap.Combinators
+       
 (* Simple expressions: syntax and semantics *)
 module Expr =
   struct
@@ -68,6 +71,11 @@ module Expr =
       | Var   x -> st x
       | Binop (op, x, y) -> to_func op (eval st x) (eval st y)
 
+    (* Statement parser *)
+    ostap (
+      parse: empty {failwith "Not implemented yet"}
+    )
+
   end
                     
 (* Simple statements: syntax and sematics *)
@@ -96,13 +104,27 @@ module Stmt =
       | Write   e       -> (st, i, o @ [Expr.eval st e])
       | Assign (x, e)   -> (Expr.update x (Expr.eval st e) st, i, o)
       | Seq    (s1, s2) -> eval (eval conf s1) s2
-                                                         
+                                
+    (* Statement parser *)
+    ostap (
+      parse: empty {failwith "Not implemented yet"}
+    )
+      
   end
 
+(* The top-level definitions *)
+
+(* The top-level syntax category is statement *)
+type t = Stmt.t    
+
 (* Top-level evaluator
 
-     val eval : int list -> Stmt.t -> int list
+     eval : t -> int list -> int list
 
-   Takes an input stream, a program, and returns the output stream this program calculates
- *)
-let eval i p = let _, _, o = Stmt.eval (Expr.empty, i, []) p in o
+   Takes a program and its input stream, and returns the output stream
+*)
+let eval p i =
+  let _, _, o = Stmt.eval (Expr.empty, i, []) p in o
+
+(* Top-level parser *)
+let parse = Stmt.parse                                                     
diff --git a/src/Makefile b/src/Makefile
index 203fdf346..5de1b4eda 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2,7 +2,7 @@ TOPFILE = rc
 OCAMLC = ocamlc
 OCAMLOPT = ocamlopt
 OCAMLDEP = ocamldep
-SOURCES = Syntax.ml Embedding.ml SM.ml
+SOURCES = Language.ml Embedding.ml SM.ml Driver.ml
 LIBS = GT.cma unix.cma re.cma re_emacs.cma re_str.cma
 CAMLP5 = -pp "camlp5o -I `ocamlfind -query GT.syntax` -I `ocamlfind -query ostap.syntax` pa_ostap.cmo pa_gt.cmo -L `ocamlfind -query GT.syntax`"
 PXFLAGS = $(CAMLP5)
@@ -21,7 +21,7 @@ $(TOPFILE).byte: $(SOURCES:.ml=.cmo)
 	$(OCAMLC) -o $(TOPFILE).byte $(BFLAGS) $(LIBS) ostap.cma $(SOURCES:.ml=.cmo) 
 
 clean:
-	rm -Rf *.cmi *.cmo *.cmx *.annot *.o *.opt *.byte *~
+	rm -Rf *.cmi *.cmo *.cmx *.annot *.o *.opt *.byte *~ .depend
 
 -include .depend
 # generic rules
diff --git a/src/SM.ml b/src/SM.ml
index 0b9297ff7..7b4dde9e3 100644
--- a/src/SM.ml
+++ b/src/SM.ml
@@ -16,7 +16,7 @@ type prg = insn list
 (* The type for the stack machine configuration: a stack and a configuration from statement
    interpreter
  *)
-type config = int list * Stmt.config
+type config = int list * Language.Stmt.config
 
 (* Stack machine interpreter
 
@@ -48,6 +48,7 @@ let run i p = let (_, (_, _, o)) = eval ([], (Expr.empty, i, [])) p in o
 (* Stack machine compiler
 
      val compile : Stmt.t -> prg
+     val compile : Language.Stmt.t -> prg
 
    Takes a program in the source language and returns an equivalent program for the
    stack machine