diff --git a/macro/MacroBison.yy b/macro/MacroBison.yy
index d1aa75dd..0addc52c 100644
--- a/macro/MacroBison.yy
+++ b/macro/MacroBison.yy
@@ -24,6 +24,8 @@
 %{
 using namespace std;
 
+#include "MacroValue.hh"
+
 class MacroDriver;
 %}
 
@@ -49,9 +51,11 @@ class MacroDriver;
 {
   string *string_val;
   int int_val;
+  MacroValue *mv;
 };
 
 %{
+#include <stdlib.h>  // Pour atoi()
 #include "MacroDriver.hh"
 
 /* this "connects" the bison parser in the driver to the flex scanner class
@@ -61,13 +65,77 @@ class MacroDriver;
 #define yylex driver.lexer->lex
 %}
 
-%token <int_val> INT_NUMBER
-%token <string_val> NAME
+%token DEFINE
+%token LPAREN RPAREN LBRACKET RBRACKET COLON EQUAL EOL
+
+%token <int_val> INTEGER
+%token <string_val> NAME STRING
+
+%left LOGICAL_OR
+%left LOGICAL_AND
+%left LESS GREATER LESS_EQUAL GREATER_EQUAL EQUAL_EQUAL EXCLAMATION_EQUAL
+%left TIMES DIVIDE
+%left PLUS MINUS
+%left UMINUS UPLUS EXCLAMATION
+%left LBRACKET
+
+%type <mv> expr
 %%
 
 %start statement_list_or_nothing;
 
-statement_list_or_nothing : /* empty */;
+statement_list_or_nothing : /* empty */
+                          | statement_list;
+
+statement_list : statement EOL
+               | statement_list statement EOL;
+
+statement : expr
+            { *driver.out_stream << $1->toString(); delete $1; }
+          | DEFINE NAME EQUAL expr
+            { driver.env[*$2] = $4; delete $2; }
+
+expr : INTEGER
+       { $$ = new IntMV($1); }
+     | STRING
+       { $$ = new StringMV(*$1); delete $1; }
+     | NAME
+       { $$ = driver.env[*$1]->clone(); delete $1; }
+     | LPAREN expr RPAREN
+       { $$ = $2; }
+     | expr PLUS expr
+       { $$ = *$1 + *$3; delete $1; delete $3; }
+     | expr MINUS expr
+       { $$ = *$1 - *$3; delete $1; delete $3; }
+     | expr TIMES expr
+       { $$ = *$1 * *$3; delete $1; delete $3; }
+     | expr DIVIDE expr
+       { $$ = *$1 / *$3; delete $1; delete $3; }
+     | expr LESS expr
+       { $$ = *$1 < *$3; delete $1; delete $3; }
+     | expr GREATER expr
+       { $$ = *$1 > *$3; delete $1; delete $3; }
+     | expr LESS_EQUAL expr
+       { $$ = *$1 <= *$3; delete $1; delete $3; }
+     | expr GREATER_EQUAL expr
+       { $$ = *$1 >= *$3; delete $1; delete $3; }
+     | expr EQUAL_EQUAL expr
+       { $$ = *$1 == *$3; delete $1; delete $3; }
+     | expr EXCLAMATION_EQUAL expr
+       { $$ = *$1 != *$3; delete $1; delete $3; }
+     | expr LOGICAL_OR expr
+       { $$ = *$1 || *$3; delete $1; delete $3; }
+     | expr LOGICAL_AND expr
+       { $$ = *$1 && *$3; delete $1; delete $3; }
+     | MINUS expr %prec UMINUS
+       { $$ = -*$2; delete $2;}
+     | PLUS expr %prec UPLUS
+       { $$ = $2; }
+     | EXCLAMATION expr
+       { $$ = !*$2; delete $2; }
+     | expr LBRACKET expr RBRACKET
+       { $$ = (*$1)[*$3]; delete $1; delete $3; }
+     ;
 
 %%
 
diff --git a/macro/MacroDriver.cc b/macro/MacroDriver.cc
index 926d027a..56c0efcd 100644
--- a/macro/MacroDriver.cc
+++ b/macro/MacroDriver.cc
@@ -34,6 +34,7 @@ void
 MacroDriver::parse(const string &f, ostream &out)
 {
   file = f;
+  out_stream = &out;
 
   ifstream in(f.c_str(), ios::binary);
 
diff --git a/macro/MacroDriver.hh b/macro/MacroDriver.hh
index e53e0cbc..e70e758a 100644
--- a/macro/MacroDriver.hh
+++ b/macro/MacroDriver.hh
@@ -27,8 +27,10 @@
 #include <string>
 #include <iostream>
 #include <stack>
+#include <map>
 
 #include "MacroBison.hh"
+#include "MacroValue.hh"
 
 using namespace std;
 
@@ -78,12 +80,18 @@ public:
   //! Stack of locations used for (possibly nested) includes
   stack<Macro::parser::location_type> loc_stack;
 
+  //! Environment (maps macro variables to their values)
+  map<string, MacroValue*> env;
+
   //! Name of main file being parsed
   string file;
 
   //! Reference to the lexer
   class MacroFlex *lexer;
 
+  //! Copy of output stream
+  ostream *out_stream;
+
   //! Trace scanning ?
   /*! If set to true before calling parse(), the flex scanner will dump a lot of debugging information. Defaults to false.
   */
diff --git a/macro/MacroFlex.ll b/macro/MacroFlex.ll
index 6f6b7ade..8bdc68cc 100644
--- a/macro/MacroFlex.ll
+++ b/macro/MacroFlex.ll
@@ -49,6 +49,7 @@ typedef Macro::parser::token token;
 
 %x INCLUDE
 %x END_INCLUDE
+%x MACRO
 
 %{
 // Increments location counter for every token read
@@ -96,6 +97,51 @@ typedef Macro::parser::token token;
                                   BEGIN(INITIAL);
                                 }
 
+<INITIAL>@                  { BEGIN(MACRO); }
+
+
+<MACRO>[ \t\r\f]+           { yylloc->step(); }
+<MACRO>@                    { BEGIN(INITIAL); return token::EOL; }
+<MACRO>\n                   { BEGIN(INITIAL); return token::EOL; }
+
+<MACRO>[0-9]+               {
+                              yylval->int_val = atoi(yytext);
+                              return token::INTEGER;
+                            }
+<MACRO>\(                   { return token::LPAREN; }
+<MACRO>\)                   { return token::RPAREN; }
+<MACRO>\[                   { return token::LBRACKET; }
+<MACRO>\]                   { return token::RBRACKET; }
+<MACRO>:                    { return token::COLON; }
+<MACRO>=                    { return token::EQUAL; }
+<MACRO>[!]                  { return token::EXCLAMATION; }
+<MACRO>"||"                 { return token::LOGICAL_OR; }
+<MACRO>&&                   { return token::LOGICAL_AND; }
+<MACRO>"<="                 { return token::LESS_EQUAL; }
+<MACRO>">="                 { return token::GREATER_EQUAL; }
+<MACRO>"<"                  { return token::LESS; }
+<MACRO>">"                  { return token::GREATER; }
+<MACRO>"=="                 { return token::EQUAL_EQUAL; }
+<MACRO>"!="                 { return token::EXCLAMATION_EQUAL; }
+<MACRO>[+]                  { return token::PLUS; }
+<MACRO>[-]                  { return token::MINUS; }
+<MACRO>[*]                  { return token::TIMES; }
+<MACRO>[/]                  { return token::DIVIDE; }
+
+<MACRO>\'[^\']*\'           {
+                              yylval->string_val = new string(yytext + 1);
+                              yylval->string_val->resize(yylval->string_val->length() - 1);
+                              return token::STRING;
+                            }
+
+<MACRO>define               { return token::DEFINE; }
+
+<MACRO>[A-Za-z_][A-Za-z0-9_]* {
+                                yylval->string_val = new string(yytext);
+                                return token::NAME;
+                              }
+
+
 <<EOF>>                     {
                               /* We don't use yypop_buffer_state(), since it doesn't exist in
                                  Flex 2.5.4 (see Flex 2.5.33 info file - section 11 - for code
@@ -116,9 +162,6 @@ typedef Macro::parser::token token;
                               BEGIN(END_INCLUDE);
                             }
 
- /* Ignore Ctrl-M */
-<INITIAL>(\r)+              { yylloc->step(); }
-
  /* Copy everything else to output */
 <INITIAL>[\n]+              { yylloc->lines(yyleng); yylloc->step(); ECHO; }
 <INITIAL>.                  { yylloc->step(); ECHO; }
diff --git a/macro/MacroValue.cc b/macro/MacroValue.cc
new file mode 100644
index 00000000..aa137dfa
--- /dev/null
+++ b/macro/MacroValue.cc
@@ -0,0 +1,290 @@
+/*
+ * Copyright (C) 2008 Dynare Team
+ *
+ * This file is part of Dynare.
+ *
+ * Dynare is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Dynare is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <sstream>
+
+#include "MacroValue.hh"
+
+MacroValue *
+MacroValue::operator-(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator - does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator-() const throw (TypeError)
+{
+  throw TypeError("Operator - does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator*(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator * does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator/(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator / does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator<(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator < does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator>(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator > does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator<=(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator <= does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator>=(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator >= does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator&&(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator && does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator||(const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator || does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator!() const throw (TypeError)
+{
+  throw TypeError("Operator ! does not exist for this type");
+}
+
+MacroValue *
+MacroValue::operator[](const MacroValue &mv) const throw (TypeError)
+{
+  throw TypeError("Operator [] does not exist for this type");
+}
+
+IntMV::IntMV(int value_arg) : value(value_arg)
+{
+}
+
+MacroValue *
+IntMV::operator+(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of + operator");
+  else
+    return new IntMV(value + mv2->value);
+}
+
+MacroValue *
+IntMV::operator-(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of - operator");
+  else
+    return new IntMV(value - mv2->value);
+}
+
+MacroValue *
+IntMV::operator-() const throw (TypeError)
+{
+  return new IntMV(-value);
+}
+
+MacroValue *
+IntMV::operator*(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of * operator");
+  else
+    return new IntMV(value * mv2->value);
+}
+
+MacroValue *
+IntMV::operator/(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of / operator");
+  else
+    return new IntMV(value / mv2->value);
+}
+
+MacroValue *
+IntMV::operator<(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of < operator");
+  else
+    return new IntMV(value < mv2->value);
+}
+
+MacroValue *
+IntMV::operator>(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of > operator");
+  else
+    return new IntMV(value > mv2->value);
+}
+
+MacroValue *
+IntMV::operator<=(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of <= operator");
+  else
+    return new IntMV(value <= mv2->value);
+}
+
+MacroValue *
+IntMV::operator>=(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of >= operator");
+  else
+    return new IntMV(value >= mv2->value);
+}
+
+MacroValue *
+IntMV::operator==(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw new IntMV(0);
+  else
+    return new IntMV(value == mv2->value);
+}
+
+MacroValue *
+IntMV::operator!=(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw new IntMV(1);
+  else
+    return new IntMV(value != mv2->value);
+}
+
+MacroValue *
+IntMV::operator&&(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of && operator");
+  else
+    return new IntMV(value && mv2->value);
+}
+
+MacroValue *
+IntMV::operator||(const MacroValue &mv) const throw (TypeError)
+{
+  const IntMV *mv2 = dynamic_cast<const IntMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of || operator");
+  else
+    return new IntMV(value || mv2->value);
+}
+
+MacroValue *
+IntMV::operator!() const throw (TypeError)
+{
+  return new IntMV(!value);
+}
+
+string
+IntMV::toString() const
+{
+  ostringstream ss;
+  ss << value;
+  return ss.str();
+}
+
+MacroValue *
+IntMV::clone() const
+{
+  return new IntMV(value);
+}
+
+StringMV::StringMV(const string &value_arg) : value(value_arg)
+{
+}
+
+MacroValue *
+StringMV::operator+(const MacroValue &mv) const throw (TypeError)
+{
+  const StringMV *mv2 = dynamic_cast<const StringMV *>(&mv);
+  if (mv2 == NULL)
+    throw TypeError("Type mismatch for operands of + operator");
+  else
+    return new StringMV(value + mv2->value);
+}
+
+MacroValue *
+StringMV::operator==(const MacroValue &mv) const throw (TypeError)
+{
+  const StringMV *mv2 = dynamic_cast<const StringMV *>(&mv);
+  if (mv2 == NULL)
+    throw new IntMV(0);
+  else
+    return new IntMV(value == mv2->value);
+}
+
+MacroValue *
+StringMV::operator!=(const MacroValue &mv) const throw (TypeError)
+{
+  const StringMV *mv2 = dynamic_cast<const StringMV *>(&mv);
+  if (mv2 == NULL)
+    throw new IntMV(1);
+  else
+    return new IntMV(value != mv2->value);
+}
+
+string
+StringMV::toString() const
+{
+  return value;
+}
+
+MacroValue *
+StringMV::clone() const
+{
+  return new StringMV(value);
+}
diff --git a/macro/MacroValue.hh b/macro/MacroValue.hh
new file mode 100644
index 00000000..31e7687c
--- /dev/null
+++ b/macro/MacroValue.hh
@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2008 Dynare Team
+ *
+ * This file is part of Dynare.
+ *
+ * Dynare is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Dynare is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _MACRO_VALUE_HH
+#define _MACRO_VALUE_HH
+
+using namespace std;
+
+#include <string>
+#include <vector>
+
+class MacroValue
+{
+public:
+  class TypeError
+  {
+  public:
+    const string message;
+    TypeError(const string &message_arg) : message(message_arg) {};
+  };
+  virtual MacroValue *operator+(const MacroValue &mv) const throw (TypeError) = 0;
+  virtual MacroValue *operator-(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator-() const throw (TypeError);
+  virtual MacroValue *operator*(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator/(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator<(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator>(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator<=(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator>=(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator==(const MacroValue &mv) const throw (TypeError) = 0;
+  virtual MacroValue *operator!=(const MacroValue &mv) const throw (TypeError) = 0;
+  virtual MacroValue *operator&&(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator||(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator!() const throw (TypeError);
+  virtual MacroValue *operator[](const MacroValue &mv) const throw (TypeError);
+  virtual string toString() const = 0;
+  virtual MacroValue *clone() const = 0;
+};
+
+class IntMV : public MacroValue
+{
+private:
+  int value;
+public:
+  IntMV(int value_arg);
+  virtual MacroValue *operator+(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator-(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator-() const throw (TypeError);
+  virtual MacroValue *operator*(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator/(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator<(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator>(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator<=(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator>=(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator==(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator!=(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator&&(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator||(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator!() const throw (TypeError);
+  virtual string toString() const;
+  virtual MacroValue *clone() const;
+};
+
+class StringMV : public MacroValue
+{
+private:
+  string value;
+public:
+  StringMV(const string &value_arg);
+  virtual MacroValue *operator+(const MacroValue &mv) const throw (TypeError);
+//   virtual MacroValue *operator<(const MacroValue &mv) const throw (TypeError);
+//   virtual MacroValue *operator>(const MacroValue &mv) const throw (TypeError);
+//   virtual MacroValue *operator<=(const MacroValue &mv) const throw (TypeError);
+//   virtual MacroValue *operator>=(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator==(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator!=(const MacroValue &mv) const throw (TypeError);
+// virtual MacroValue *operator[](const MacroValue &mv) const throw (TypeError);
+  virtual string toString() const;
+  virtual MacroValue *clone() const;
+};
+
+/*
+class IntArrayMV : public MacroValue
+{
+private:
+  vector<int> values;
+public:
+  IntArrayMV(const vector<int> &values_arg);
+  virtual MacroValue *operator+(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator==(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator!=(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator[](const MacroValue &mv) const throw (TypeError);
+  virtual string toString() const;
+  virtual MacroValue *clone() const;
+};
+
+class StringArrayMV : public MacroValue
+{
+private:
+  vector<string> values;
+public:
+  StringArrayMV(const vector<string> &values_arg);
+  virtual MacroValue *operator+(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator==(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator!=(const MacroValue &mv) const throw (TypeError);
+  virtual MacroValue *operator[](const MacroValue &mv) const throw (TypeError);
+  virtual string toString() const;
+  virtual MacroValue *clone() const;
+};
+*/
+
+#endif
diff --git a/macro/Makefile b/macro/Makefile
index fbf27271..8ce93aa9 100644
--- a/macro/Makefile
+++ b/macro/Makefile
@@ -1,6 +1,6 @@
 include ../Makefile.include
 
-OBJ = MacroFlex.o MacroBison.o MacroDriver.o
+OBJ = MacroFlex.o MacroBison.o MacroDriver.o MacroValue.o
 
 libmacro.a: $(OBJ)
 	$(AR) crs libmacro.a $(OBJ)