diff --git a/bin/main.ml b/bin/main.ml
index d36a83e..3afdbd6 100644
--- a/bin/main.ml
+++ b/bin/main.ml
@@ -1,8 +1,15 @@
+open Syntax.Roots
+
+let get_lexbuf () =
+  if Array.length Sys.argv > 1 then
+    let file_path = Sys.argv.(1) in
+    let file_stream = open_in file_path in
+    Lexing.from_channel file_stream
+  else Lexing.from_channel stdin
+
 let () =
-  let file_path = Sys.argv.(1) in
-  let file_stream = open_in file_path in
-  let lexbuf = Lexing.from_channel file_stream in
-  let ast =
+  let lexbuf = get_lexbuf () in
+  let ast : program =
     try Analyzer.Parser.main Analyzer.Lexer.token lexbuf with
     | Analyzer.Lexer.Error c ->
         let file_name = lexbuf.lex_curr_p.pos_fname
@@ -20,4 +27,5 @@ let () =
           file_name line_num col_num "Erreur syntaxique" "Syntaxe incorrecte";
         exit 1
   in
-  Printf.printf "%s\n" (Syntax.SourceFiles.pp_source_files ast)
\ No newline at end of file
+  let _ = ast#check_type in
+  Printf.printf "%s\n" (Syntax.Literals.string_of_literal_value ast#eval)
\ No newline at end of file
diff --git a/lib/analyzer/dune b/lib/analyzer/dune
index d209510..a905f01 100644
--- a/lib/analyzer/dune
+++ b/lib/analyzer/dune
@@ -1,7 +1,7 @@
 (library
- (name Analyzer)
+ (name analyzer)
  (modules lexer parser)
- (libraries Syntax))
+ (libraries syntax))
 
 (menhir
  (modules parser))
diff --git a/lib/analyzer/lexer.mll b/lib/analyzer/lexer.mll
index 77fe331..9a62205 100644
--- a/lib/analyzer/lexer.mll
+++ b/lib/analyzer/lexer.mll
@@ -33,7 +33,8 @@ rule token = parse
   | '+' { PLUS }
   | '-' { MINUS }
   | '*' { TIMES }
-  | '/' { DIV }
+  | '/' { DIVIDE }
+  | "=" { EQUAL }
   | "==" { EQUAL_EQUAL }
   | "!=" { NOT_EQUAL }
   | "<" { LESS_THAN }
@@ -43,16 +44,24 @@ rule token = parse
   | "&&" { AMPERSAND_AMPERSAND }
   | "||" { BAR_BAR }
   | "!" { EXCLAMATION }
+  | ":" { COLON }
 
   (* Keywords *)
   | "vrai" { BOOLEAN(true) }
   | "faux" { BOOLEAN(false) }
+  | "var" { VAR }
+  | "entier" { INTEGER_TYPE }
+  | "flottant" { FLOAT_TYPE }
+  | "booleen" { BOOLEAN_TYPE }
+  | "chaine" { STRING_TYPE }
+  | "caractere" { CHARACTER_TYPE }
+  | "nul" { NULL_TYPE }
+  | "vide" { VOID_TYPE }
 
   (* Literals *)
-  | interger as i { INT (int_of_string i) }
+  | interger as i { INTEGER (int_of_string i) }
   | float as f { FLOAT (float_of_string f) }
   | '"' { Buffer.clear buffer; STRING(string lexbuf) }
-  | "''" { NULL }
   | "'\\''"    { CHARACTER '\'' }
   | "'\\n'"    { CHARACTER '\n' }
   | "'\\t'"    { CHARACTER '\t' }
diff --git a/lib/analyzer/parser.mly b/lib/analyzer/parser.mly
index 42c8ea6..8dd9558 100644
--- a/lib/analyzer/parser.mly
+++ b/lib/analyzer/parser.mly
@@ -2,18 +2,28 @@
 open Syntax
 %}
 
-%token <int> INT
+%token <int> INTEGER
 %token <float> FLOAT
 %token <char> CHARACTER
 %token <bool> BOOLEAN
 %token <string> STRING
 %token <string> IDENTIFIER
-%token NULL
+
+%token EQUAL "="
+%token VAR
+
+%token INTEGER_TYPE
+%token FLOAT_TYPE
+%token BOOLEAN_TYPE
+%token STRING_TYPE
+%token CHARACTER_TYPE
+%token NULL_TYPE
+%token VOID_TYPE
 
 %token PLUS "+"
 %token MINUS "-"
 %token TIMES "*"
-%token DIV "/"
+%token DIVIDE "/"
 %token EQUAL_EQUAL "=="
 %token NOT_EQUAL "!="
 %token LESS_THAN "<"
@@ -25,6 +35,7 @@ open Syntax
 %token EXCLAMATION "!"
 
 %token SEMICOLON ";"
+%token COLON ":"
 
 %token LPAREN "("
 %token RPAREN ")"
@@ -36,49 +47,59 @@ open Syntax
 
 %nonassoc UMINUS
 
-%start <SourceFiles.source_files> main
+%start <Roots.program> main
 
 %%
 
 main:
-  | statements EOF { SourceFiles.SourceFile $1 }
+  | statements EOF { new Roots.program $1 }
 
 statements:
   | statement ";"            { $1 }
-  | statement ";" statements { Statements.SequenceStatement ($1, $3) }
+  | statement ";" statements { new Statements.sequence $1 $3 }
 
 statement:
-  | expression  { Statements.ExpressionStatement($1) }
+  | expression  { new Statements.expression $1 }
+  | VAR IDENTIFIER ":" tp "=" expression { new Statements.variableDeclaration $2 $4 $6 }
 
 expression:
-  | literal            { Expressions.Literal($1) }
-  | IDENTIFIER         { Expressions.Identifier($1) }
+  | literal            { new Expressions.literal $1 }
+  | IDENTIFIER         { new Expressions.identifier $1 }
   | unary_expression   { $1 }
   | binary_expression  { $1 }
   | "(" expression ")" { $2 }
 
+tp:
+  | INTEGER_TYPE { Types.IntegerType }
+  | FLOAT_TYPE { Types.FloatType }
+  | BOOLEAN_TYPE { Types.BooleanType }
+  | STRING_TYPE { Types.StringType }
+  | CHARACTER_TYPE { Types.CharacterType }
+  | NULL_TYPE { Types.NullType }
+  | VOID_TYPE { Types.VoidType }
+
 literal:
-  | INT { Literals.Integer($1) }
-  | FLOAT { Literals.Float($1) }
-  | BOOLEAN { Literals.Boolean($1) }
-  | CHARACTER { Literals.Character($1) }
-  | STRING { Literals.String($1) }
-  | NULL { Literals.Null }
+  | INTEGER { new Literals.eInteger $1 }
+  | FLOAT { new Literals.eFloat $1 }
+  | BOOLEAN { new Literals.eBoolean $1 }
+  | CHARACTER { new Literals.eCharacter $1 }
+  | STRING { new Literals.eString $1 }
+  | NULL_TYPE { new Literals.eNull }
 
 unary_expression:
-  | "-" expression %prec UMINUS { Expressions.UnaryExpression(UnaryOperators.ArithmeticNegation, $2) }
-  | "!" expression { Expressions.UnaryExpression(UnaryOperators.LogicalNegation, $2) }
+  | "-" expression %prec UMINUS { new Expressions.unaryOperation (new UnaryOperators.arithmeticNegation) $2 }
+  | "!" expression              { new Expressions.unaryOperation (new UnaryOperators.logicalNegation) $2 }
 
 binary_expression:
-  | expression "+" expression { Expressions.BinaryExpression (BinaryOperators.Add, $1, $3) }
-  | expression "-" expression { Expressions.BinaryExpression (BinaryOperators.Subtract, $1, $3) }
-  | expression "*" expression { Expressions.BinaryExpression (BinaryOperators.Multiply, $1, $3) }
-  | expression "/" expression { Expressions.BinaryExpression (BinaryOperators.Divide, $1, $3) }
-  | expression "==" expression { Expressions.BinaryExpression (BinaryOperators.Equals, $1, $3) }
-  | expression "!=" expression { Expressions.BinaryExpression (BinaryOperators.NotEquals, $1, $3) }
-  | expression "<" expression { Expressions.BinaryExpression (BinaryOperators.LessThan, $1, $3) }
-  | expression "<=" expression { Expressions.BinaryExpression (BinaryOperators.LessThanEquals, $1, $3) }
-  | expression ">" expression { Expressions.BinaryExpression (BinaryOperators.GreaterThan, $1, $3) }
-  | expression ">=" expression { Expressions.BinaryExpression (BinaryOperators.GreaterThanEquals, $1, $3) }
-  | expression "&&" expression { Expressions.BinaryExpression (BinaryOperators.And, $1, $3) }
-  | expression "||" expression { Expressions.BinaryExpression (BinaryOperators.Or, $1, $3) }
\ No newline at end of file
+  | expression "+" expression  { new Expressions.binaryOperation (new BinaryOperators.add) $1 $3 }
+  | expression "-" expression  { new Expressions.binaryOperation (new BinaryOperators.subtract) $1 $3 }
+  | expression "*" expression  { new Expressions.binaryOperation (new BinaryOperators.multiply) $1 $3 }
+  | expression "/" expression  { new Expressions.binaryOperation (new BinaryOperators.divide) $1 $3 }
+  | expression "==" expression { new Expressions.binaryOperation (new BinaryOperators.equals) $1 $3 }
+  | expression "!=" expression { new Expressions.binaryOperation (new BinaryOperators.notEquals) $1 $3 }
+  | expression "<" expression  { new Expressions.binaryOperation (new BinaryOperators.lessThan) $1 $3 }
+  | expression "<=" expression { new Expressions.binaryOperation (new BinaryOperators.lessThanEquals) $1 $3 }
+  | expression ">" expression  { new Expressions.binaryOperation (new BinaryOperators.greaterThan) $1 $3 }
+  | expression ">=" expression { new Expressions.binaryOperation (new BinaryOperators.greaterThanEquals) $1 $3 }
+  | expression "&&" expression { new Expressions.binaryOperation (new BinaryOperators.logicalAnd) $1 $3 }
+  | expression "||" expression { new Expressions.binaryOperation (new BinaryOperators.logicalOr) $1 $3 }
\ No newline at end of file
diff --git a/lib/analyzer/typing.ml b/lib/analyzer/typing.ml
deleted file mode 100644
index c23a5fe..0000000
--- a/lib/analyzer/typing.ml
+++ /dev/null
@@ -1 +0,0 @@
-type environment = { variables : (string * Types.types) list }
\ No newline at end of file
diff --git a/lib/dune b/lib/dune
index 08baaba..729160c 100644
--- a/lib/dune
+++ b/lib/dune
@@ -1,3 +1,3 @@
 (library
  (name Croissant)
- (libraries Syntax Analyzer))
+ (libraries syntax analyzer))
diff --git a/lib/syntax/BinaryOperators.ml b/lib/syntax/BinaryOperators.ml
index 7a83041..afc2343 100644
--- a/lib/syntax/BinaryOperators.ml
+++ b/lib/syntax/BinaryOperators.ml
@@ -1,27 +1,265 @@
-type binary_operators =
-  | Add
-  | Subtract
-  | Multiply
-  | Divide
-  | Equals
-  | NotEquals
-  | LessThan
-  | LessThanEquals
-  | GreaterThan
-  | GreaterThanEquals
-  | And
-  | Or
+class virtual binaryOperator =
+  object
+    inherit Node.node
+    method virtual check_type : Types.t * Types.t -> Types.t
 
-let pp_binary_operators = function
-  | Add -> "Add"
-  | Subtract -> "Subtract"
-  | Multiply -> "Multiply"
-  | Divide -> "Divide"
-  | Equals -> "Equals"
-  | NotEquals -> "NotEquals"
-  | LessThan -> "LessThan"
-  | LessThanEquals -> "LessThanEquals"
-  | GreaterThan -> "GreaterThan"
-  | GreaterThanEquals -> "GreaterThanEquals"
-  | And -> "And"
-  | Or -> "Or"
\ No newline at end of file
+    method virtual eval
+        : Literals.literal_value * Literals.literal_value ->
+          Literals.literal_value
+  end
+
+class add =
+  object
+    inherit binaryOperator
+    method to_string = "Add"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.IntegerType, Types.IntegerType -> Types.IntegerType
+      | Types.FloatType, Types.FloatType -> Types.FloatType
+      | Types.FloatType, Types.IntegerType -> Types.FloatType
+      | Types.IntegerType, Types.FloatType -> Types.FloatType
+      | Types.StringType, Types.StringType -> Types.StringType
+      | _ -> raise (Failure "Add: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Int (a + b)
+      | `Float a, `Float b -> `Float (a +. b)
+      | `Float a, `Int b -> `Float (a +. float_of_int b)
+      | `Int a, `Float b -> `Float (float_of_int a +. b)
+      | `String a, `String b -> `String (a ^ b) (* Concatenation *)
+      | _ -> raise (Failure "Add: operands must be numbers")
+  end
+
+class subtract =
+  object
+    inherit binaryOperator
+    method to_string = "Subtract"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.IntegerType, Types.IntegerType -> Types.IntegerType
+      | Types.FloatType, Types.FloatType -> Types.FloatType
+      | Types.FloatType, Types.IntegerType -> Types.FloatType
+      | Types.IntegerType, Types.FloatType -> Types.FloatType
+      | _ -> raise (Failure "Subtract: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Int (a - b)
+      | `Float a, `Float b -> `Float (a -. b)
+      | `Float a, `Int b -> `Float (a -. float_of_int b)
+      | `Int a, `Float b -> `Float (float_of_int a -. b)
+      | _ -> raise (Failure "Subtract: operands must be numbers")
+  end
+
+class multiply =
+  object
+    inherit binaryOperator
+    method to_string = "Multiply"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.IntegerType, Types.IntegerType -> Types.FloatType
+      | Types.FloatType, Types.FloatType -> Types.FloatType
+      | Types.FloatType, Types.IntegerType -> Types.FloatType
+      | Types.IntegerType, Types.FloatType -> Types.FloatType
+      | _ -> raise (Failure "Multiply: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Float (float_of_int a *. float_of_int b)
+      | `Float a, `Float b -> `Float (a *. b)
+      | `Float a, `Int b -> `Float (a *. float_of_int b)
+      | `Int a, `Float b -> `Float (float_of_int a *. b)
+      | _ -> raise (Failure "Multiply: operands must be numbers")
+  end
+
+class divide =
+  object
+    inherit binaryOperator
+    method to_string = "Divide"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.IntegerType, Types.IntegerType -> Types.FloatType
+      | Types.FloatType, Types.FloatType -> Types.FloatType
+      | Types.FloatType, Types.IntegerType -> Types.FloatType
+      | Types.IntegerType, Types.FloatType -> Types.FloatType
+      | _ -> raise (Failure "Divide: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Float (float_of_int a /. float_of_int b)
+      | `Float a, `Float b -> `Float (a /. b)
+      | `Float a, `Int b -> `Float (a /. float_of_int b)
+      | `Int a, `Float b -> `Float (float_of_int a /. b)
+      | _ -> raise (Failure "Divide: operands must be numbers")
+  end
+
+class equals =
+  object
+    inherit binaryOperator
+    method to_string = "Equals"
+
+    method check_type (left, right) =
+      if left = right then Types.BooleanType
+      else raise (Failure "Equals: operands must have the same type")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Bool (a = b)
+      | `Float a, `Float b -> `Bool (a = b)
+      | `Float a, `Int b -> `Bool (a = float_of_int b)
+      | `Int a, `Float b -> `Bool (float_of_int a = b)
+      | `String a, `String b -> `Bool (a = b)
+      | `Bool a, `Bool b -> `Bool (a = b)
+      | `Char a, `Char b -> `Bool (a = b)
+      | `Null, `Null -> `Bool true
+      | `Void, `Void -> `Bool true
+      | _ -> raise (Failure "Equals: operands must have the same type")
+  end
+
+class notEquals =
+  object
+    inherit binaryOperator
+    method to_string = "NotEquals"
+
+    method check_type (left, right) =
+      if left = right then Types.BooleanType
+      else raise (Failure "Equals: operands must have the same type")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Bool (a <> b)
+      | `Float a, `Float b -> `Bool (a <> b)
+      | `Float a, `Int b -> `Bool (a <> float_of_int b)
+      | `Int a, `Float b -> `Bool (float_of_int a <> b)
+      | `String a, `String b -> `Bool (a <> b)
+      | `Bool a, `Bool b -> `Bool (a <> b)
+      | `Char a, `Char b -> `Bool (a <> b)
+      | `Null, `Null -> `Bool false
+      | `Void, `Void -> `Bool false
+      | _ -> raise (Failure "NotEquals: operands must have the same type")
+  end
+
+class lessThan =
+  object
+    inherit binaryOperator
+    method to_string = "LessThan"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.IntegerType, Types.IntegerType -> Types.BooleanType
+      | Types.FloatType, Types.FloatType -> Types.BooleanType
+      | Types.FloatType, Types.IntegerType -> Types.BooleanType
+      | Types.IntegerType, Types.FloatType -> Types.BooleanType
+      | _ -> raise (Failure "LessThan: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Bool (a < b)
+      | `Float a, `Float b -> `Bool (a < b)
+      | `Float a, `Int b -> `Bool (a < float_of_int b)
+      | `Int a, `Float b -> `Bool (float_of_int a < b)
+      | _ -> raise (Failure "LessThan: operands must be numbers")
+  end
+
+class lessThanEquals =
+  object
+    inherit binaryOperator
+    method to_string = "LessThanEquals"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.IntegerType, Types.IntegerType -> Types.BooleanType
+      | Types.FloatType, Types.FloatType -> Types.BooleanType
+      | Types.FloatType, Types.IntegerType -> Types.BooleanType
+      | Types.IntegerType, Types.FloatType -> Types.BooleanType
+      | _ -> raise (Failure "LessThanEquals: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Bool (a <= b)
+      | `Float a, `Float b -> `Bool (a <= b)
+      | `Float a, `Int b -> `Bool (a <= float_of_int b)
+      | `Int a, `Float b -> `Bool (float_of_int a <= b)
+      | _ -> raise (Failure "LessThanEquals: operands must be numbers")
+  end
+
+class greaterThan =
+  object
+    inherit binaryOperator
+    method to_string = "GreaterThan"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.IntegerType, Types.IntegerType -> Types.BooleanType
+      | Types.FloatType, Types.FloatType -> Types.BooleanType
+      | Types.FloatType, Types.IntegerType -> Types.BooleanType
+      | Types.IntegerType, Types.FloatType -> Types.BooleanType
+      | _ -> raise (Failure "GreaterThan: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Bool (a > b)
+      | `Float a, `Float b -> `Bool (a > b)
+      | `Float a, `Int b -> `Bool (a > float_of_int b)
+      | `Int a, `Float b -> `Bool (float_of_int a > b)
+      | _ -> raise (Failure "GreaterThan: operands must be numbers")
+  end
+
+class greaterThanEquals =
+  object
+    inherit binaryOperator
+    method to_string = "GreaterThanEquals"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.IntegerType, Types.IntegerType -> Types.BooleanType
+      | Types.FloatType, Types.FloatType -> Types.BooleanType
+      | Types.FloatType, Types.IntegerType -> Types.BooleanType
+      | Types.IntegerType, Types.FloatType -> Types.BooleanType
+      | _ -> raise (Failure "GreaterThanEquals: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Int a, `Int b -> `Bool (a >= b)
+      | `Float a, `Float b -> `Bool (a >= b)
+      | `Float a, `Int b -> `Bool (a >= float_of_int b)
+      | `Int a, `Float b -> `Bool (float_of_int a >= b)
+      | _ -> raise (Failure "GreaterThanEquals: operands must be numbers")
+  end
+
+class logicalAnd =
+  object
+    inherit binaryOperator
+    method to_string = "And"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.BooleanType, Types.BooleanType -> Types.BooleanType
+      | _ -> raise (Failure "And: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Bool a, `Bool b -> `Bool (a && b)
+      | _ -> raise (Failure "And: operands must be booleans")
+  end
+
+class logicalOr =
+  object
+    inherit binaryOperator
+    method to_string = "Or"
+
+    method check_type (left, right) =
+      match (left, right) with
+      | Types.BooleanType, Types.BooleanType -> Types.BooleanType
+      | _ -> raise (Failure "Or: operands must be numbers")
+
+    method eval (left, right) =
+      match (left, right) with
+      | `Bool a, `Bool b -> `Bool (a || b)
+      | _ -> raise (Failure "Or: operands must be booleans")
+  end
\ No newline at end of file
diff --git a/lib/syntax/Environments.ml b/lib/syntax/Environments.ml
new file mode 100644
index 0000000..7d01583
--- /dev/null
+++ b/lib/syntax/Environments.ml
@@ -0,0 +1,27 @@
+class evalEnvironment =
+  object
+    val mutable env : (string, Literals.literal_value) Hashtbl.t =
+      Hashtbl.create 10
+
+    method add (name : string) (lit : Literals.literal_value) =
+      Hashtbl.add env name lit
+
+    method find (name : string) = Hashtbl.find env name
+
+    method clone : evalEnvironment =
+      let new_env = new evalEnvironment in
+      Hashtbl.iter (fun k v -> new_env#add k v) env;
+      new_env
+  end
+
+class typeEnvironments =
+  object
+    val mutable env : (string, Types.t) Hashtbl.t = Hashtbl.create 10
+    method add (name : string) (tp : Types.t) = Hashtbl.add env name tp
+    method find (name : string) = Hashtbl.find env name
+
+    method clone : typeEnvironments =
+      let new_env = new typeEnvironments in
+      Hashtbl.iter (fun k v -> new_env#add k v) env;
+      new_env
+  end
\ No newline at end of file
diff --git a/lib/syntax/Expressions.ml b/lib/syntax/Expressions.ml
index dcfade7..851e3c0 100644
--- a/lib/syntax/Expressions.ml
+++ b/lib/syntax/Expressions.ml
@@ -1,23 +1,59 @@
-open Literals
-open UnaryOperators
-open BinaryOperators
+class virtual expression =
+  object
+    inherit Node.node
+    method virtual check_type : Environments.typeEnvironments -> Types.t
+    method virtual eval : Environments.evalEnvironment -> Literals.literal_value
+  end
 
-type expressions =
-  | Literal of literals
-  | Identifier of string
-  | UnaryExpression of unary_operators * expressions
-  | BinaryExpression of binary_operators * expressions * expressions
+class literal (lit : Literals.literal) =
+  object
+    inherit expression
+    method to_string = "Literal(" ^ lit#to_string ^ ")"
+    method check_type _ = lit#check_type
+    method eval _ = lit#value
+  end
 
-let rec pp_expressions = function
-  | Literal l ->
-      let pp_l = pp_literals l in
-      Printf.sprintf "Literal(%s)" pp_l
-  | Identifier i -> Printf.sprintf "Identifier(\"%s\")" i
-  | UnaryExpression (op, e) ->
-      let pp_op = pp_unary_operators op and pp_e = pp_expressions e in
-      Printf.sprintf "UnaryExpression(%s, %s)" pp_op pp_e
-  | BinaryExpression (op, e1, e2) ->
-      let pp_op = pp_binary_operators op
-      and pp_e1 = pp_expressions e1
-      and pp_e2 = pp_expressions e2 in
-      Printf.sprintf "BinaryExpression(%s, %s, %s)" pp_op pp_e1 pp_e2
\ No newline at end of file
+class identifier (name : string) =
+  object
+    inherit expression
+    method to_string = "Identifier(" ^ name ^ ")"
+
+    method check_type env =
+      try env#find name
+      with Not_found ->
+        raise (Failure ("Identifier '" ^ name ^ "' not found"))
+
+    method eval env = env#find name
+  end
+
+class unaryOperation (operator : UnaryOperators.unaryOperator)
+  (operand : expression) =
+  object
+    inherit expression
+
+    method to_string =
+      "UnaryOperation(" ^ operator#to_string ^ ", " ^ operand#to_string ^ ")"
+
+    method check_type env =
+      let operand_type = operand#check_type env in
+      operator#check_type operand_type
+
+    method eval env = operator#eval (operand#eval env)
+  end
+
+class binaryOperation (operator : BinaryOperators.binaryOperator)
+  (left : expression) (right : expression) =
+  object
+    inherit expression
+
+    method to_string =
+      "BinaryOperation(" ^ operator#to_string ^ ", " ^ left#to_string ^ ", "
+      ^ right#to_string ^ ")"
+
+    method check_type env =
+      let left_type = left#check_type env in
+      let right_type = right#check_type env in
+      operator#check_type (left_type, right_type)
+
+    method eval env = operator#eval (left#eval env, right#eval env)
+  end
\ No newline at end of file
diff --git a/lib/syntax/Literals.ml b/lib/syntax/Literals.ml
index f9f3bf3..3792ca1 100644
--- a/lib/syntax/Literals.ml
+++ b/lib/syntax/Literals.ml
@@ -1,15 +1,80 @@
-type literals =
-  | Integer of int
-  | Float of float
-  | Character of char
-  | String of string
-  | Boolean of bool
-  | Null
+type literal_value =
+  [ `Int of int
+  | `Float of float
+  | `String of string
+  | `Bool of bool
+  | `Char of char
+  | `Null
+  | `Void ]
 
-let pp_literals = function
-  | Integer i -> Printf.sprintf "Integer(%d)" i
-  | Float f -> Printf.sprintf "Float(%f)" f
-  | Character c -> Printf.sprintf "Character('%c')" c
-  | String s -> Printf.sprintf "String(\"%s\")" s
-  | Boolean b -> Printf.sprintf "Boolean(%b)" b
-  | Null -> "Null"
\ No newline at end of file
+let string_of_literal_value = function
+  | `Int i -> string_of_int i
+  | `Float f -> string_of_float f
+  | `String s -> "\"" ^ s ^ "\""
+  | `Bool b -> string_of_bool b
+  | `Char c -> "'" ^ String.make 1 c ^ "'"
+  | `Null -> "null"
+  | `Void -> "void"
+
+class virtual literal =
+  object
+    inherit Node.node
+    method virtual value : literal_value
+    method virtual check_type : Types.t
+  end
+
+class eInteger (value : int) =
+  object
+    inherit literal
+    method value = `Int value
+    method to_string = "Integer(" ^ string_of_int value ^ ")"
+    method check_type = Types.IntegerType
+  end
+
+class eFloat (value : float) =
+  object
+    inherit literal
+    method value = `Float value
+    method to_string : string = "Float(" ^ string_of_float value ^ ")"
+    method check_type = Types.FloatType
+  end
+
+class eString (value : string) =
+  object
+    inherit literal
+    method value = `String value
+    method to_string = "String(\"" ^ value ^ "\")"
+    method check_type = Types.StringType
+  end
+
+class eBoolean (value : bool) =
+  object
+    inherit literal
+    method value = `Bool value
+    method to_string = "Boolean(" ^ string_of_bool value ^ ")"
+    method check_type = Types.BooleanType
+  end
+
+class eCharacter (value : char) =
+  object
+    inherit literal
+    method value = `Char value
+    method to_string = "Character(" ^ String.make 1 value ^ ")"
+    method check_type = Types.CharacterType
+  end
+
+class eNull =
+  object
+    inherit literal
+    method value = `Null
+    method to_string = "Null"
+    method check_type = Types.NullType
+  end
+
+class eVoid =
+  object
+    inherit literal
+    method value = `Void
+    method to_string = "Void"
+    method check_type = Types.VoidType
+  end
\ No newline at end of file
diff --git a/lib/syntax/Node.ml b/lib/syntax/Node.ml
new file mode 100644
index 0000000..769c4b8
--- /dev/null
+++ b/lib/syntax/Node.ml
@@ -0,0 +1,6 @@
+class virtual node =
+  object
+    method virtual to_string : string
+    (*    method virtual check_type : Types.type_ *)
+    (* method virtual eval *)
+  end
\ No newline at end of file
diff --git a/lib/syntax/Roots.ml b/lib/syntax/Roots.ml
new file mode 100644
index 0000000..3205461
--- /dev/null
+++ b/lib/syntax/Roots.ml
@@ -0,0 +1,17 @@
+class program (statement : Statements.statement) =
+  object
+    inherit Node.node
+    method to_string = "Program(" ^ statement#to_string ^ ")"
+
+    method check_type =
+      let env : Environments.typeEnvironments =
+        new Environments.typeEnvironments
+      in
+      statement#check_type env
+
+    method eval =
+      let env : Environments.evalEnvironment =
+        new Environments.evalEnvironment
+      in
+      statement#eval env
+  end
\ No newline at end of file
diff --git a/lib/syntax/SourceFiles.ml b/lib/syntax/SourceFiles.ml
deleted file mode 100644
index ea99f83..0000000
--- a/lib/syntax/SourceFiles.ml
+++ /dev/null
@@ -1,8 +0,0 @@
-open Statements
-
-type source_files = SourceFile of statements
-
-let pp_source_files = function
-  | SourceFile stmts ->
-      let pp_stmt = pp_statements stmts in
-      Printf.sprintf "SourceFile(%s)" pp_stmt
\ No newline at end of file
diff --git a/lib/syntax/Statements.ml b/lib/syntax/Statements.ml
index ef12427..fd25610 100644
--- a/lib/syntax/Statements.ml
+++ b/lib/syntax/Statements.ml
@@ -1,13 +1,52 @@
-open Expressions
+class virtual statement =
+  object
+    inherit Node.node
+    method virtual check_type : Environments.typeEnvironments -> Types.t
+    method virtual eval : Environments.evalEnvironment -> Literals.literal_value
+  end
 
-type statements =
-  | SequenceStatement of statements * statements
-  | ExpressionStatement of expressions
+class sequence (left : statement) (right : statement) =
+  object
+    inherit statement
 
-let rec pp_statements = function
-  | SequenceStatement (stmt1, stmt2) ->
-      let pp_stmt1 = pp_statements stmt1 and pp_stmt2 = pp_statements stmt2 in
-      Printf.sprintf "SequenceStatement(%s, %s)" pp_stmt1 pp_stmt2
-  | ExpressionStatement expr ->
-      let pp_expr = pp_expressions expr in
-      Printf.sprintf "ExpressionStatement(%s)" pp_expr
+    method to_string =
+      "Sequence(" ^ left#to_string ^ ", " ^ right#to_string ^ ")"
+
+    method check_type env =
+      let _ = left#check_type env in
+      right#check_type env
+
+    method eval env =
+      let _ = left#eval env in
+      right#eval env
+  end
+
+class expression (expression : Expressions.expression) =
+  object
+    inherit statement
+    method to_string = "Expression(" ^ expression#to_string ^ ")"
+    method check_type env = expression#check_type env
+    method eval env = expression#eval env
+  end
+
+class variableDeclaration (name : string) (tp : Types.t)
+  (expression : Expressions.expression) =
+  object
+    inherit statement
+
+    method to_string =
+      "VariableDeclaration(" ^ name ^ ", " ^ Types.string_of_t tp ^ ", "
+      ^ expression#to_string ^ ")"
+
+    method check_type env =
+      let expression_type = expression#check_type env in
+      if tp = expression_type then (
+        env#add name expression_type;
+        Types.VoidType)
+      else raise (Failure "VariableDeclaration: type mismatch")
+
+    method eval env =
+      let value = expression#eval env in
+      env#add name value;
+      value
+  end
\ No newline at end of file
diff --git a/lib/syntax/Types.ml b/lib/syntax/Types.ml
index 106c427..c267579 100644
--- a/lib/syntax/Types.ml
+++ b/lib/syntax/Types.ml
@@ -1,15 +1,17 @@
-type types =
+type t =
   | IntegerType
   | FloatType
-  | CharacterType
-  | StringType
   | BooleanType
+  | StringType
+  | CharacterType
+  | NullType
   | VoidType
 
-let pp_types = function
+let string_of_t = function
   | IntegerType -> "IntegerType"
   | FloatType -> "FloatType"
-  | CharacterType -> "CharacterType"
-  | StringType -> "StringType"
   | BooleanType -> "BooleanType"
-  | VoidType -> "VoidType"
+  | StringType -> "StringType"
+  | CharacterType -> "CharacterType"
+  | NullType -> "NullType"
+  | VoidType -> "VoidType"
\ No newline at end of file
diff --git a/lib/syntax/UnaryOperators.ml b/lib/syntax/UnaryOperators.ml
index bb6cd61..bf2a61d 100644
--- a/lib/syntax/UnaryOperators.ml
+++ b/lib/syntax/UnaryOperators.ml
@@ -1,5 +1,40 @@
-type unary_operators = ArithmeticNegation | LogicalNegation
+class virtual unaryOperator =
+  object
+    inherit Node.node
+    method virtual check_type : Types.t -> Types.t
+    method virtual eval : Literals.literal_value -> Literals.literal_value
+  end
 
-let pp_unary_operators = function
-  | ArithmeticNegation -> "ArithmeticNegation"
-  | LogicalNegation -> "LogicalNegation"
+class arithmeticNegation =
+  object
+    inherit unaryOperator
+    method to_string = "ArithmeticNegation"
+
+    method check_type (operand : Types.t) =
+      match operand with
+      | Types.IntegerType -> Types.IntegerType
+      | Types.FloatType -> Types.FloatType
+      | _ -> raise (Failure "ArithmeticNegation: operand must be a number")
+
+    method eval operand =
+      match operand with
+      | `Int i -> `Int (-i)
+      | `Float f -> `Float (-.f)
+      | _ -> raise (Failure "ArithmeticNegation: operand must be a number")
+  end
+
+class logicalNegation =
+  object
+    inherit unaryOperator
+    method to_string = "LogicalNegation"
+
+    method check_type (operand : Types.t) =
+      match operand with
+      | Types.BooleanType -> Types.BooleanType
+      | _ -> raise (Failure "LogicalNegation: operand must be a boolean")
+
+    method eval operand =
+      match operand with
+      | `Bool b -> `Bool (not b)
+      | _ -> raise (Failure "LogicalNegation: operand must be a boolean")
+  end
\ No newline at end of file
diff --git a/lib/syntax/dune b/lib/syntax/dune
index d14a6c1..825e84d 100644
--- a/lib/syntax/dune
+++ b/lib/syntax/dune
@@ -1,10 +1,14 @@
 (library
- (name Syntax)
+ (name syntax)
  (modules
+  Node
   Types
-  Literals
+  Environments
   BinaryOperators
   UnaryOperators
+  Literals
   Expressions
   Statements
-  SourceFiles))
+  Roots)
+; (libraries typing)
+)
diff --git a/test/ressources/test.🥐 b/test/ressources/test.🥐
deleted file mode 100644
index d9a2b18..0000000
--- a/test/ressources/test.🥐
+++ /dev/null
@@ -1 +0,0 @@
-!vrai;
\ No newline at end of file
diff --git a/test/syntax/TestBinaryOperators.ml b/test/syntax/TestBinaryOperators.ml
deleted file mode 100644
index a31fd1d..0000000
--- a/test/syntax/TestBinaryOperators.ml
+++ /dev/null
@@ -1,30 +0,0 @@
-open Alcotest
-open Syntax.BinaryOperators
-
-let test_pp_binary_operators () =
-  let to_check =
-    [
-      ("Should return \"Add\"", "Add", Add);
-      ("Should return \"Subtract\"", "Subtract", Subtract);
-      ("Should return \"Multiply\"", "Multiply", Multiply);
-      ("Should return \"Divide\"", "Divide", Divide);
-      ("Should return \"Equals\"", "Equals", Equals);
-      ("Should return \"NotEquals\"", "NotEquals", NotEquals);
-      ("Should return \"LessThan\"", "LessThan", LessThan);
-      ("Should return \"LessThanEquals\"", "LessThanEquals", LessThanEquals);
-      ("Should return \"GreaterThan\"", "GreaterThan", GreaterThan);
-      ( "Should return \"GreaterThanEquals\"",
-        "GreaterThanEquals",
-        GreaterThanEquals );
-      ("Should return \"And\"", "And", And);
-      ("Should return \"Or\"", "Or", Or);
-    ]
-  in
-  List.iter
-    (fun (msg, expected, actual) ->
-      check string msg expected (pp_binary_operators actual))
-    to_check
-
-let tests =
-  ( "BinaryOperators",
-    [ test_case "pp_binary_operators" `Quick test_pp_binary_operators ] )
\ No newline at end of file
diff --git a/test/syntax/TestExpressions.ml b/test/syntax/TestExpressions.ml
deleted file mode 100644
index 2022928..0000000
--- a/test/syntax/TestExpressions.ml
+++ /dev/null
@@ -1,32 +0,0 @@
-open Alcotest
-open Syntax
-
-let test_pp_expressions () =
-  let to_check =
-    [
-      ( "Should return \"Literal(...)\"",
-        "Literal(Integer(1))",
-        Expressions.Literal (Literals.Integer 1) );
-      ( "Should return \"Identifier(...)\"",
-        "Identifier(\"myVar\")",
-        Expressions.Identifier "myVar" );
-      ( "Should return \"UnaryExpression(...)\"",
-        "UnaryExpression(ArithmeticNegation, Literal(Integer(2)))",
-        Expressions.UnaryExpression
-          ( UnaryOperators.ArithmeticNegation,
-            Expressions.Literal (Literals.Integer 2) ) );
-      ( "Should return \"BinaryExpression(...)\"",
-        "BinaryExpression(Add, Literal(Integer(5)), Literal(Integer(10)))",
-        Expressions.BinaryExpression
-          ( BinaryOperators.Add,
-            Expressions.Literal (Literals.Integer 5),
-            Expressions.Literal (Literals.Integer 10) ) );
-    ]
-  in
-  List.iter
-    (fun (msg, expected, actual) ->
-      check string msg expected (Expressions.pp_expressions actual))
-    to_check
-
-let tests =
-  ("Expressions", [ test_case "pp_expressions" `Quick test_pp_expressions ])
\ No newline at end of file
diff --git a/test/syntax/TestLiterals.ml b/test/syntax/TestLiterals.ml
deleted file mode 100644
index 75fd10a..0000000
--- a/test/syntax/TestLiterals.ml
+++ /dev/null
@@ -1,22 +0,0 @@
-open Alcotest
-open Syntax.Literals
-
-let test_pp_literals () =
-  let to_check =
-    [
-      ("Should return \"Integer(1)\"", "Integer(1)", Integer 1);
-      ("Should return \"Float(1.000000)\"", "Float(1.000000)", Float 1.0);
-      ( "Should return \"String(\\\"Hello, World!\\\")\"",
-        "String(\"Hello, World!\")",
-        String "Hello, World!" );
-      ("Should return \"Character('c')\"", "Character('c')", Character 'c');
-      ("Should return \"Boolean(true)\"", "Boolean(true)", Boolean true);
-      ("Should return \"Boolean(false)\"", "Boolean(false)", Boolean false);
-    ]
-  in
-  List.iter
-    (fun (msg, expected, actual) ->
-      check string msg expected (pp_literals actual))
-    to_check
-
-let tests = ("Literals", [ test_case "pp_literals" `Quick test_pp_literals ])
\ No newline at end of file
diff --git a/test/syntax/TestSourceFiles.ml b/test/syntax/TestSourceFiles.ml
deleted file mode 100644
index 4800822..0000000
--- a/test/syntax/TestSourceFiles.ml
+++ /dev/null
@@ -1,24 +0,0 @@
-open Alcotest
-open Syntax
-
-let test_pp_source_files () =
-  let to_check =
-    [
-      ( "Should return \"SourceFile(...)\"",
-        "SourceFile(ExpressionStatement(BinaryExpression(Add, \
-         Literal(Integer(1)), Literal(Integer(2)))))",
-        SourceFiles.SourceFile
-          (Statements.ExpressionStatement
-             (Expressions.BinaryExpression
-                ( BinaryOperators.Add,
-                  Expressions.Literal (Literals.Integer 1),
-                  Expressions.Literal (Literals.Integer 2) ))) );
-    ]
-  in
-  List.iter
-    (fun (name, expected, actual) ->
-      check string name expected (SourceFiles.pp_source_files actual))
-    to_check
-
-let tests =
-  ("SourceFiles", [ test_case "pp_source_files" `Quick test_pp_source_files ])
\ No newline at end of file
diff --git a/test/syntax/TestStatements.ml b/test/syntax/TestStatements.ml
deleted file mode 100644
index b6e866e..0000000
--- a/test/syntax/TestStatements.ml
+++ /dev/null
@@ -1,27 +0,0 @@
-open Alcotest
-open Syntax
-
-let test_pp_statements () =
-  let to_check =
-    [
-      ( "Should return \"ExpressionStatement(...)\"",
-        "ExpressionStatement(Literal(Integer(1)))",
-        Statements.ExpressionStatement
-          (Expressions.Literal (Literals.Integer 1)) );
-      ( "Should return \"SequenceStatement(...)\"",
-        "SequenceStatement(ExpressionStatement(Literal(Integer(1))), \
-         ExpressionStatement(Literal(Float(1.000000))))",
-        Statements.SequenceStatement
-          ( Statements.ExpressionStatement
-              (Expressions.Literal (Literals.Integer 1)),
-            Statements.ExpressionStatement
-              (Expressions.Literal (Literals.Float 1.0)) ) );
-    ]
-  in
-  List.iter
-    (fun (name, expected, actual) ->
-      check string name expected (Statements.pp_statements actual))
-    to_check
-
-let tests =
-  ("Statements", [ test_case "pp_statements" `Quick test_pp_statements ])
\ No newline at end of file
diff --git a/test/syntax/TestSyntax.ml b/test/syntax/TestSyntax.ml
deleted file mode 100644
index 548204a..0000000
--- a/test/syntax/TestSyntax.ml
+++ /dev/null
@@ -1,13 +0,0 @@
-open Alcotest
-
-let () =
-  run "Syntax"
-    [
-      TestTypes.tests;
-      TestLiterals.tests;
-      TestUnaryOperators.tests;
-      TestBinaryOperators.tests;
-      TestExpressions.tests;
-      TestStatements.tests;
-      TestSourceFiles.tests;
-    ]
\ No newline at end of file
diff --git a/test/syntax/TestTypes.ml b/test/syntax/TestTypes.ml
deleted file mode 100644
index 61ea3a9..0000000
--- a/test/syntax/TestTypes.ml
+++ /dev/null
@@ -1,18 +0,0 @@
-open Alcotest
-open Syntax.Types
-
-let test_pp_types () =
-  let to_check =
-    [
-      ("Should return \"IntegerType\"", "IntegerType", IntegerType);
-      ("Should return \"BooleanType\"", "BooleanType", BooleanType);
-      ("Should return \"StringType\"", "StringType", StringType);
-      ("Should return \"CharacterType\"", "CharacterType", CharacterType);
-      ("Should return \"VoidType\"", "VoidType", VoidType);
-    ]
-  in
-  List.iter
-    (fun (msg, expected, input) -> check string msg expected (pp_types input))
-    to_check
-
-let tests = ("Types", [ test_case "pp_types" `Quick test_pp_types ])
\ No newline at end of file
diff --git a/test/syntax/TestUnaryOperators.ml b/test/syntax/TestUnaryOperators.ml
deleted file mode 100644
index 021cb1a..0000000
--- a/test/syntax/TestUnaryOperators.ml
+++ /dev/null
@@ -1,19 +0,0 @@
-open Alcotest
-open Syntax.UnaryOperators
-
-let test_pp_unary_operators () =
-  let to_check =
-    [
-      ( "Should return \"ArithmeticNegation\"",
-        ArithmeticNegation,
-        "ArithmeticNegation" );
-    ]
-  in
-  List.iter
-    (fun (msg, unary_operator, expected) ->
-      check string msg expected (pp_unary_operators unary_operator))
-    to_check
-
-let tests =
-  ( "UnaryOperators",
-    [ test_case "pp_unary_operators" `Quick test_pp_unary_operators ] )
\ No newline at end of file
diff --git a/test/syntax/dune b/test/syntax/dune
deleted file mode 100644
index 0a0e0a0..0000000
--- a/test/syntax/dune
+++ /dev/null
@@ -1,4 +0,0 @@
-(test
-  (name TestSyntax)
-  (libraries Syntax alcotest)
-)
\ No newline at end of file
diff --git a/test/test.🥐 b/test/test.🥐
new file mode 100644
index 0000000..bd60462
--- /dev/null
+++ b/test/test.🥐
@@ -0,0 +1,5 @@
+var a : entier = 5;         // 5
+var b : flottant = a + 3.8; // 8.8
+var c : flottant = b * a;   // 44.0
+
+var d : chaine = "Hello" + "World"; // "HelloWorld"
\ No newline at end of file