diff --git a/lib/primitives.ml b/lib/primitives.ml
index 228e6d2..1c75c07 100644
--- a/lib/primitives.ml
+++ b/lib/primitives.ml
@@ -2,6 +2,7 @@ type address = string
 type uint = UInt of int
 type sint = SInt of int
 
+
 let caller () = assert false
 
 (* binary operators for unsigned int *)
@@ -15,3 +16,10 @@ let ( + ) (SInt x) (SInt y) = SInt (x + y)
 let ( - ) (SInt x) (SInt y) = SInt (x - y)
 let ( * ) (SInt x) (SInt y) = SInt (x * y)
 let ( / ) (SInt x) (SInt y) = SInt (x / y)
+
+(* operations for boolean *)
+(* let ( && ) b1 b2 = b1 && b2
+let ( || ) b1 b2 = b1 || b2
+let not b = not b
+let (==) b1 b2 = b1 == b2
+let (!=) b1 b2 = not (b1 == b2) *)
\ No newline at end of file
diff --git a/lib/primitives.mli b/lib/primitives.mli
index 115d3fa..450dd44 100644
--- a/lib/primitives.mli
+++ b/lib/primitives.mli
@@ -1,6 +1,7 @@
 type address
 type uint = UInt of int
 type sint = SInt of int
+(* type bool_ = bool *)
 
 val caller : unit -> address
 
@@ -15,3 +16,9 @@ val ( + ) : sint -> sint -> sint
 val ( - ) : sint -> sint -> sint
 val ( * ) : sint -> sint -> sint
 val ( / ) : sint -> sint -> sint
+
+(* val ( && ) : bool_ -> bool_ -> bool_
+val ( || ) : bool_ -> bool_ -> bool_
+val not : bool_ -> bool_
+val ( == ) : bool_ -> bool_ -> bool_
+val ( != ) : bool_ -> bool_ -> bool_ *)
\ No newline at end of file
diff --git a/sample/contract_test/SimpleStorageIf.test.js b/sample/contract_test/SimpleStorageIf.test.js
new file mode 100644
index 0000000..06466ec
--- /dev/null
+++ b/sample/contract_test/SimpleStorageIf.test.js
@@ -0,0 +1,75 @@
+const assert = require('assert');
+const ganache = require('ganache');
+const { Web3 } = require('web3');
+
+const web3 = new Web3(ganache.provider())
+
+const { abi, bytecode } = require('../contracts/SimpleStorageIf.json');
+
+describe('SimpleStorageIf', async () => {
+  let accounts;
+  let contract;
+  let from;
+
+  beforeEach(async () => {
+    accounts = await web3.eth.getAccounts();
+    from = accounts[0];
+
+    contract = await new web3.eth.Contract(JSON.parse(JSON.stringify(abi)))
+      .deploy({ data: bytecode })
+      .send({ from: accounts[0], gas: 1000000 });
+
+    await contract.methods.set(100).send({ from: from });
+  });
+
+  it('should deploy', () => {
+    assert.ok(contract.options.address);
+  });
+
+  it('getting value', async () => {
+    const v = await contract.methods.get(from).call();
+    assert.equal(100, v);
+  });
+
+  it('setting value', async () => {
+    await contract.methods.set(200).send({ from: from });
+    const v = await contract.methods.get().call();
+    assert.equal(200, v);
+  });
+
+  it('is less than value', async () => {
+    const v = await contract.methods.lt(1, 2).call();
+    assert.equal(true, v);
+  });
+
+  it('is greater than value', async () => {
+    const v = await contract.methods.gt(1, 2).call();
+    assert.equal(false, v);
+  });
+
+  it('is less than equal value', async () => {
+    const v = await contract.methods.lte(1, 1).call();
+    assert.equal(true, v);
+  });
+
+  it('is greater than equal value', async () => {
+    const v = await contract.methods.gte(1, 1).call();
+    assert.equal(true, v);
+  });
+
+  it('calculate xor', async () => {
+    const v = await contract.methods.xor(true, true).call();
+    assert.equal(false, v);
+  });
+
+  it('equalize xor2 to xor', async () => {
+    const v = await contract.methods.xor(false, true).call();
+    const v2 = await contract.methods.xor2(false, true).call();
+    assert.equal(v, v2);
+  });
+
+  it('calculate max', async () => {
+    const v = await contract.methods.max(5, 3).call();
+    assert.equal(5, v);
+  });
+});
\ No newline at end of file
diff --git a/sample/contracts/SimpleStorageIf.json b/sample/contracts/SimpleStorageIf.json
new file mode 100644
index 0000000..cd1aeda
--- /dev/null
+++ b/sample/contracts/SimpleStorageIf.json
@@ -0,0 +1,84 @@
+{
+  "contractName": "SimpleStorageIf",
+  "abi": [
+    {
+      "name": "max",
+      "type": "function",
+      "inputs": [
+        { "name": "", "type": "int256" }, { "name": "", "type": "int256" }
+      ],
+      "outputs": [ { "name": "", "type": "int256" } ],
+      "stateMutability": "view"
+    },
+    {
+      "name": "xor2",
+      "type": "function",
+      "inputs": [
+        { "name": "", "type": "bool" }, { "name": "", "type": "bool" }
+      ],
+      "outputs": [ { "name": "", "type": "bool" } ],
+      "stateMutability": "view"
+    },
+    {
+      "name": "xor",
+      "type": "function",
+      "inputs": [
+        { "name": "", "type": "bool" }, { "name": "", "type": "bool" }
+      ],
+      "outputs": [ { "name": "", "type": "bool" } ],
+      "stateMutability": "view"
+    },
+    {
+      "name": "gte",
+      "type": "function",
+      "inputs": [
+        { "name": "", "type": "int256" }, { "name": "", "type": "int256" }
+      ],
+      "outputs": [ { "name": "", "type": "bool" } ],
+      "stateMutability": "view"
+    },
+    {
+      "name": "lte",
+      "type": "function",
+      "inputs": [
+        { "name": "", "type": "int256" }, { "name": "", "type": "int256" }
+      ],
+      "outputs": [ { "name": "", "type": "bool" } ],
+      "stateMutability": "view"
+    },
+    {
+      "name": "gt",
+      "type": "function",
+      "inputs": [
+        { "name": "", "type": "int256" }, { "name": "", "type": "int256" }
+      ],
+      "outputs": [ { "name": "", "type": "bool" } ],
+      "stateMutability": "view"
+    },
+    {
+      "name": "lt",
+      "type": "function",
+      "inputs": [
+        { "name": "", "type": "int256" }, { "name": "", "type": "int256" }
+      ],
+      "outputs": [ { "name": "", "type": "bool" } ],
+      "stateMutability": "view"
+    },
+    {
+      "name": "get",
+      "type": "function",
+      "inputs": [],
+      "outputs": [ { "name": "", "type": "int256" } ],
+      "stateMutability": "view"
+    },
+    {
+      "name": "set",
+      "type": "function",
+      "inputs": [ { "name": "", "type": "int256" } ],
+      "outputs": [],
+      "stateMutability": "nonpayable"
+    }
+  ],
+  "bytecode": "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",
+  "deployedBytecode": "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"
+}
\ No newline at end of file
diff --git a/sample/src/simple_hash_if.ml b/sample/src/simple_hash_if.ml
deleted file mode 100644
index 70acd17..0000000
--- a/sample/src/simple_hash_if.ml
+++ /dev/null
@@ -1,31 +0,0 @@
-open OCamYul.Primitives
-
-module SimpleHashIf : sig
-  type storage
-  type mut_storage
-
-  val set : address * uint -> storage -> mut_storage -> unit * storage
-  val get : address -> storage -> mut_storage -> uint * storage
-  val set_caller : uint -> storage -> mut_storage -> unit * storage
-end = struct
-  type storage = unit
-  type mut_storage = (address, uint) Hashtbl.t
-
-  let set (x, y) () h =
-    (if true then let a = UInt 2 in let b = UInt 3 in let c = a +^ b in Hashtbl.replace h x y else ()); let a = if false then SInt 1 else SInt 2 in let b = SInt 2 in let c = a + b in 
-    ((), ())
-
-  let get x () h = 
-    let a = 
-      if let c = true in c 
-        then SInt 1 
-        else let b = if false 
-          then SInt 3
-          else SInt 4 in b + b
-    in (Hashtbl.find h x, ())
-
-
-  let set_caller x () h =
-    Hashtbl.replace h (caller ()) x;
-    ((), ())
-end
diff --git a/sample/src/simple_storage_if.ml b/sample/src/simple_storage_if.ml
new file mode 100644
index 0000000..b2abc3d
--- /dev/null
+++ b/sample/src/simple_storage_if.ml
@@ -0,0 +1,36 @@
+open OCamYul.Primitives
+
+module SimpleStorageIf : sig
+  type storage
+
+  val set : sint -> storage -> unit * storage
+  val get : unit -> storage -> sint * storage
+  val lt : sint * sint -> storage -> bool * storage
+  val gt : sint * sint -> storage -> bool * storage
+  val lte : sint * sint -> storage -> bool * storage
+  val gte : sint * sint -> storage -> bool * storage
+  val xor : bool * bool -> storage -> bool * storage
+  val xor2 : bool * bool -> storage -> bool * storage
+  val max : sint * sint -> storage -> sint * storage
+end = struct
+  type storage = sint
+
+  let set n _ = ((), n)
+  let get () s = (s, s)
+  let lt (x, y) s = (x < y, s)
+  let gt (x, y) s = (x > y, s)
+  let lte (x, y) s = (x <= y, s)
+  let gte (x, y) s = (x >= y, s)
+
+  let xor (x, y) s =
+    let b = (x || y) && not (x && y) in
+    (b, s)
+
+  let xor2 (x, y) s =
+    let b = if x then (if y then false else true) else (if y then true else false) in
+    (b, s)
+
+  let max (n, m) s =
+    let b = n > m in
+    ((if b then n else m), s)
+end
diff --git a/src/abi.ml b/src/abi.ml
index ebcfa60..0512eb0 100644
--- a/src/abi.ml
+++ b/src/abi.ml
@@ -9,7 +9,7 @@ type abi = {
 and input = { input_name : string; input_type : param_type }
 and output = { output_name : string; output_type : param_type }
 and abi_type = Func
-and param_type = Uint256 | Int256 | Address
+and param_type = Uint256 | Int256 | Address | Bool
 and state_mutability = Pure | View | Nonpayable | Payable
 
 let stronger_mutability mut1 mut2 =
@@ -23,6 +23,7 @@ let string_of_param_type = function
   | Uint256 -> "uint256"
   | Int256 -> "int256"
   | Address -> "address"
+  | Bool -> "bool"
 
 let string_of_mutability = function
   | Pure -> "pure"
diff --git a/src/abi.mli b/src/abi.mli
index 2bbaab5..33fe050 100644
--- a/src/abi.mli
+++ b/src/abi.mli
@@ -10,7 +10,7 @@ type abi = {
 and input = { input_name : string; input_type : param_type }
 and output = { output_name : string; output_type : param_type }
 and abi_type = Func
-and param_type = Uint256 | Int256 | Address
+and param_type = Uint256 | Int256 | Address | Bool
 and state_mutability = Pure | View | Nonpayable | Payable
 
 val string_of_mutability : state_mutability -> string
diff --git a/src/anormal_ir.ml b/src/anormal_ir.ml
index 1fcb5fc..8ed332a 100644
--- a/src/anormal_ir.ml
+++ b/src/anormal_ir.ml
@@ -9,7 +9,26 @@ let const_to_aval = function
   | _ -> assert false
 
 let get_bop s =
-  if s = "+^" then UAdd
+  match s with
+    | "+^" -> UAdd
+    | "-^" -> USub
+    | "*^" -> UMul
+    | "/^" -> UDiv
+    | "+" -> SAdd
+    | "-" -> SSub
+    | "*" -> SMul
+    | "/" -> SDiv
+    | "&&" -> And
+    | "||" -> Or
+    | "not" -> Not
+    | "=" -> Eq
+    | "!=" -> Neq
+    | "<" -> Lt
+    | ">" -> Gt
+    | "<=" -> Lte
+    | ">=" -> Gte
+    | _ -> assert false
+  (*if s = "+^" then UAdd
   else if s = "-^" then USub
   else if s = "*^" then UMul
   else if s = "/^" then UDiv
@@ -17,7 +36,7 @@ let get_bop s =
   else if s = "-" then SSub
   else if s = "*" then SMul
   else if s = "/" then SDiv
-  else assert false
+  else assert false*)
 
 (* operation functions made usable especially, such as replace caller*)
 let pdot_to_aval p s =
@@ -32,6 +51,7 @@ let pdot_to_aval p s =
       if Ident.name id = "OCamYul" then
         if s = "caller" then Caller else Bop (get_bop s)
       else assert false
+  | Path.Pident id -> if Ident.name id = "Stdlib" then Bop (get_bop s) else assert false
   | _ -> assert false
 
   (* The first argument p is a storage. To check whether the storage changes, it is needed. 
diff --git a/src/normalized_common_ast.ml b/src/normalized_common_ast.ml
index 0f631bf..6dd371f 100644
--- a/src/normalized_common_ast.ml
+++ b/src/normalized_common_ast.ml
@@ -1,4 +1,4 @@
-type bop = UAdd | USub | UMul | UDiv | SAdd | SSub | SMul | SDiv
+type bop = UAdd | USub | UMul | UDiv | SAdd | SSub | SMul | SDiv | And | Or | Not | Eq | Neq | Lt | Gt | Lte | Gte
 
 type value =
   | Var of string
@@ -20,6 +20,15 @@ let string_of_bop = function
   | SSub -> "-"
   | SMul -> "*"
   | SDiv -> "/"
+  | And -> "&&"
+  | Or -> "||"
+  | Not -> "not"
+  | Eq -> "="
+  | Neq -> "!="
+  | Lt -> "<"
+  | Gt -> ">"
+  | Lte -> "<="
+  | Gte -> ">="
 
 let string_of_value = function
   | Var s -> s
diff --git a/src/normalized_common_ast.mli b/src/normalized_common_ast.mli
index cef95ef..4b75e6c 100644
--- a/src/normalized_common_ast.mli
+++ b/src/normalized_common_ast.mli
@@ -1,5 +1,5 @@
 (** binary operators for signed/unsigned integers *)
-type bop = UAdd | USub | UMul | UDiv | SAdd | SSub | SMul | SDiv
+type bop = UAdd | USub | UMul | UDiv | SAdd | SSub | SMul | SDiv | And | Or | Not | Eq | Neq | Lt | Gt | Lte | Gte
 
 (** a common part of value expressions *)
 type value =
diff --git a/src/ocamyul.ml b/src/ocamyul.ml
index 29237ef..caf47fe 100644
--- a/src/ocamyul.ml
+++ b/src/ocamyul.ml
@@ -50,7 +50,9 @@ let abi_input_of_typ typ =
   let abi_of_constr = function
     | Ttyp_constr (Path.Pident s, _, _) ->
         let s = Ident.name s in
-        if s = "unit" then [] else raise Not_implemented
+        if s = "unit" then [] 
+        else if s = "bool" then [ { input_name = ""; input_type = Bool } ]
+        else raise Not_implemented
     | Ttyp_constr (Path.Pdot (_, s), _, _) ->
         if s = "uint" then [ { input_name = ""; input_type = Uint256 } ]
         else if s = "sint" then [ { input_name = ""; input_type = Int256 } ]
@@ -71,7 +73,9 @@ let abi_output_of_typ typ =
   let abi_of_constr = function
     | Ttyp_constr (Path.Pident s, _, _) ->
         let s = Ident.name s in
-        if s = "unit" then [] else raise Not_implemented
+        if s = "unit" then [] 
+        else if s = "bool" then [ { output_name = ""; output_type = Bool } ]
+        else raise Not_implemented
     | Ttyp_constr (Path.Pdot (_, s), _, _) ->
         if s = "uint" then [ { output_name = ""; output_type = Uint256 } ]
         else if s = "sint" then [ { output_name = ""; output_type = Int256 } ]
@@ -170,6 +174,7 @@ let params_of_external_function { abi_inputs = inputs; _ } =
     | Uint256 -> decode_as_uint
     | Int256 -> decode_as_uint
     | Address -> decode_as_address
+    | Bool -> decode_as_bool
   in
   let rec aux n = function
     | [] -> []
diff --git a/src/yul_ast.ml b/src/yul_ast.ml
index a793ffd..f32309d 100644
--- a/src/yul_ast.ml
+++ b/src/yul_ast.ml
@@ -230,6 +230,7 @@ let get_hash_slot = "getHashSlot"
 let selector = "selector"
 let decode_as_uint = "decodeAsUint"
 let decode_as_address = "decodeAsAddress"
+let decode_as_bool = "decodeAsBool"
 let uint_add = "uintAdd"
 let uint_sub = "uintSub"
 let uint_mul = "uintMul"
@@ -366,6 +367,17 @@ let decode_as_address_def =
       [ Assign ((return_arg, []), FunctionCall (decode_as_uint, [ ID arg ])) ]
     )
 
+    let decode_as_bool_def =
+      let arg = "offset" in
+      let return_arg = "v" in
+      FunctionDef
+      ( decode_as_bool,
+        [ arg ],
+        [ return_arg ],
+        [ Assign ((return_arg, []), FunctionCall (decode_as_uint, [ ID arg ])) ]
+      )
+    
+
 let default_revert_def =
   Default [ Exp (EVM (Revert (Literal (Dec 0), Literal (Dec 0)))) ]
 
@@ -544,11 +556,11 @@ let sint_div_def =
    adding some functions to default happens in different phases *)
 
 let default_function_defs =
-  ref [ selector_def; decode_as_uint_def; decode_as_address_def ]
+  ref [ selector_def; decode_as_uint_def; decode_as_address_def; decode_as_bool_def ]
 
 let reset_default_function_defs () =
   default_function_defs :=
-    [ selector_def; decode_as_uint_def; decode_as_address_def ]
+    [ selector_def; decode_as_uint_def; decode_as_address_def; decode_as_bool_def ]
 
 let get_default_function_defs () = !default_function_defs
 
diff --git a/src/yul_ast.mli b/src/yul_ast.mli
index c253480..e1cbff1 100644
--- a/src/yul_ast.mli
+++ b/src/yul_ast.mli
@@ -73,6 +73,7 @@ val get_hash_slot : id
 val selector : id
 val decode_as_uint : id
 val decode_as_address : id
+val decode_as_bool : id
 val uint_add : id
 val uint_sub : id
 val uint_mul : id
@@ -93,6 +94,7 @@ val get_hash_slot_def : statement
 val selector_def : statement
 val decode_as_uint_def : statement
 val decode_as_address_def : statement
+val decode_as_bool_def : statement
 val default_revert_def : default
 val uint_add_def : statement
 val uint_sub_def : statement
diff --git a/src/yul_compile.ml b/src/yul_compile.ml
index a4790d6..fd49b39 100644
--- a/src/yul_compile.ml
+++ b/src/yul_compile.ml
@@ -55,7 +55,17 @@ let letexp_to_yul = function
       | SAdd -> gen_bop_call sint_add_def sint_add
       | SSub -> gen_bop_call sint_sub_def sint_sub
       | SMul -> gen_bop_call sint_mul_def sint_mul
-      | SDiv -> gen_bop_call sint_div_def sint_div)
+      | SDiv -> gen_bop_call sint_div_def sint_div
+      | And -> assert false
+      | Or -> assert false
+      | Eq -> EVM (Eq (v1, v2))
+      | Neq -> EVM (Iszero (EVM (Eq (v1, v2))))
+      | Lt -> EVM (Lt (v1, v2))
+      | Gt -> EVM (Gt (v1, v2))
+      | Lte -> EVM (Iszero (EVM (Gt (v1, v2))))
+      | Gte -> EVM (Iszero (EVM (Lt (v1, v2))))
+      | _ -> assert false)
+  | LApp (Bop Not,[v]) -> let v = aval_to_yul v in EVM (Iszero v)
   | LApp (HashReplace, [ h; x; y ]) ->
       EVM
         (Sstore
@@ -95,6 +105,14 @@ let rec translate_body_aux e acc ret_vars=
         let v = aval_to_yul v in  
         let acc = Switch (v, [Case(Dec 1, e1_block); Case(Dec 0, e2_block)], Default []) :: (Let((List.hd vars, List.tl vars), Literal (Dec 0))) :: acc in   (*initialization with 0*)
         translate_body_aux e2 acc ret_vars
+        | LApp (Bop ((And | Or) as b), [v1; v2]) -> 
+          assert (List.length vars = 1);
+          let var = List.hd vars in
+          let v1 = aval_to_yul v1 in
+          let v2 = aval_to_yul v2 in
+          let bexp = (match b with And -> v1 | Or -> EVM (Iszero v1)| _ -> assert false) in
+          let acc = (Yul_ast.If (bexp, [Assign ((var, []), v2)])) :: Let ((var, []), v1) :: acc in
+          translate_body_aux e2 acc ret_vars
         |_ -> let acc = Let ((List.hd vars, List.tl vars), letexp_to_yul e1) :: acc in
         translate_body_aux e2 acc ret_vars) in a
   | If (v, e1, e2) ->