diff --git a/lib/src/analysis/type_analyze.rs b/lib/src/analysis/type_analyze.rs
index f4f5130..23d9d41 100644
--- a/lib/src/analysis/type_analyze.rs
+++ b/lib/src/analysis/type_analyze.rs
@@ -1,5 +1,6 @@
 use crate::ast::*;
 use crate::context::Scope;
+use smallvec::smallvec;
 
 /// Type analysis attribute
 #[derive(Clone, Default)]
@@ -98,13 +99,24 @@ impl AstVisitorMut for TypeAnalyzer {
 
     fn visit_operator_expression_mut(&mut self, expr: &mut OperatorExpression) {
         // collect all operands type
-        let mut operands_attr = vec![];
+        let mut operands_attr: SmallVec3<_> = smallvec![];
         for operand in expr.operands_mut() {
             self.push(TypeAnalyzerAttribute::default());
             self.visit_expression_mut(operand);
             operands_attr.push(self.pop());
         }
 
+        // Set operator result type
+        let op_type = match operands_attr.len() {
+            1 => operands_attr[0].derived_type.clone(),
+            2 => analyze_op_expr_type(
+                &operands_attr[0].derived_type,
+                &operands_attr[1].derived_type,
+            ),
+            _ => None,
+        };
+        expr.set_ty(op_type);
+
         // let ref mut result_type = self.top_mut().derived_type;
         // for attr in operands_attr {
         //     if let Some(true) = attr
@@ -151,3 +163,54 @@ impl AstVisitorMut for TypeAnalyzer {
         self.top_mut().derived_type = attr.derived_type
     }
 }
+
+fn analyze_op_expr_type(op1: &Option<Type>, op2: &Option<Type>) -> Option<Type> {
+    let tc1 = op1.as_ref()?.type_class();
+    let tc2 = op2.as_ref()?.type_class();
+
+    // Usertype is not handled
+    if matches!(tc1, TypeClass::UserType(..)) {
+        return None;
+    }
+    if matches!(tc2, TypeClass::UserType(..)) {
+        return None;
+    }
+
+    // Array is not handled
+    if matches!(tc1, TypeClass::Array(..)) {
+        return None;
+    }
+    if matches!(tc2, TypeClass::Array(..)) {
+        return None;
+    }
+
+    // Same type
+    if tc1 == tc2 {
+        return op1.clone();
+    }
+
+    match tc1 {
+        // BitType can implicit convert to any type except String
+        TypeClass::Bit => match tc2 {
+            TypeClass::String => None,
+            _ => op2.clone(),
+        },
+
+        TypeClass::Bool => match tc2 {
+            TypeClass::Bit => op1.clone(),
+            _ => None,
+        },
+
+        TypeClass::Byte => match tc2 {
+            TypeClass::Bit => op1.clone(),
+            TypeClass::SInt | TypeClass::UInt | TypeClass::Int => op2.clone(),
+            _ => unimplemented!("{:?}", op2),
+        },
+
+        TypeClass::Int => match tc2 {
+            TypeClass::Byte | TypeClass::SInt | TypeClass::Bit => op1.clone(),
+            _ => None,
+        },
+        _ => unimplemented!("{:?}", op1),
+    }
+}
diff --git a/lib/src/ast/expression.rs b/lib/src/ast/expression.rs
index c0a909e..8837544 100644
--- a/lib/src/ast/expression.rs
+++ b/lib/src/ast/expression.rs
@@ -22,7 +22,7 @@ pub enum ExprKind {
 
 #[derive(Debug)]
 pub struct Expression {
-    pub kind: ExprKind,
+    pub(crate) kind: ExprKind,
 }
 
 impl_ast_display!(Expression, visit_expression);
@@ -37,6 +37,7 @@ impl Expression {
     }
 
     /// Get type of this expression
+    #[inline]
     pub fn ty(&self) -> Option<&Type> {
         match &self.kind {
             ExprKind::Variable(var_expr) => var_expr.ty(),
diff --git a/lib/src/ast/mod.rs b/lib/src/ast/mod.rs
index b45b204..24f3218 100644
--- a/lib/src/ast/mod.rs
+++ b/lib/src/ast/mod.rs
@@ -2,6 +2,7 @@ use bitflags::bitflags;
 use smallvec::SmallVec;
 use std::cell::RefCell;
 use std::fmt::{self, Debug, Display, Formatter};
+use std::hash::{Hash, Hasher};
 use std::rc::Rc;
 
 use crate::parser::{LiteralValue, Operator, StString};
@@ -321,6 +322,34 @@ pub enum TypeClass {
     Array(RefCell<ArrayType>),
 }
 
+impl Hash for TypeClass {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        let tag = match self {
+            TypeClass::Bit => 1,
+            TypeClass::Bool => 2,
+            TypeClass::Byte => 3,
+            TypeClass::UInt => 4,
+            TypeClass::Int => 5,
+            _ => unimplemented!("{:?}", self),
+        };
+
+        tag.hash(state);
+
+        // TODO: incomplete implements
+        match self {
+            TypeClass::UserType(user_type) => {
+                user_type.borrow().name().hash(state);
+            }
+            TypeClass::Array(array_type) => {
+                let array_type = array_type.borrow();
+                let base_type = array_type.base_type().borrow();
+                base_type.type_class().hash(state);
+            }
+            _ => {}
+        }
+    }
+}
+
 impl Display for TypeClass {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         match self {
diff --git a/lib/src/ast/types.rs b/lib/src/ast/types.rs
index 7081517..1ddafed 100644
--- a/lib/src/ast/types.rs
+++ b/lib/src/ast/types.rs
@@ -190,6 +190,11 @@ impl ArrayType {
             dimensions,
         }
     }
+
+    #[inline]
+    pub fn base_type(&self) -> &RefCell<Type> {
+        &self.base_type
+    }
 }
 
 impl Display for ArrayType {
@@ -219,4 +224,4 @@ impl From<ArrayType> for Type {
 
         Type::from_class(class)
     }
-}
\ No newline at end of file
+}
diff --git a/lib/src/ast/visitor.rs b/lib/src/ast/visitor.rs
index e746f8e..b758044 100644
--- a/lib/src/ast/visitor.rs
+++ b/lib/src/ast/visitor.rs
@@ -1,12 +1,5 @@
-#![allow(dead_code)]
-
 use crate::ast::call_expression::CallExpression;
-use crate::ast::{
-    AliasDeclare, AssignExpression, CompoAccessExpression, DeclKind, Declaration, EnumDeclare,
-    ExprKind, ExprStatement, Expression, FunctionDeclare, GlobalVariableDeclare, IfStatement,
-    LiteralExpression, OperatorExpression, Statement, StmtKind, StructDeclare, Variable,
-    VariableExpression,
-};
+use crate::ast::*;
 
 use super::RangeExpression;
 
diff --git a/lib/src/parser/mod.rs b/lib/src/parser/mod.rs
index 0e5b744..ecabe4b 100644
--- a/lib/src/parser/mod.rs
+++ b/lib/src/parser/mod.rs
@@ -16,6 +16,15 @@ pub use operator::Operator;
 mod token;
 pub use token::TokenKind;
 
+#[macro_export]
+macro_rules! parse_statement {
+    ($code: literal) => {{
+        let mut lexer = StLexerBuilder::new().build_str($code);
+        let parser = ParserBuilder::default().build();
+        parser.parse_stmt(&mut lexer)
+    }};
+}
+
 #[cfg(test)]
 mod test;
 
diff --git a/lib/src/serde/mod.rs b/lib/src/serde/mod.rs
index c7cde75..e47263a 100644
--- a/lib/src/serde/mod.rs
+++ b/lib/src/serde/mod.rs
@@ -1,2 +1,2 @@
 mod xml;
-pub use xml::Application;
+pub use xml::Project;
diff --git a/lib/src/serde/xml.rs b/lib/src/serde/xml.rs
index c314f40..942da3f 100644
--- a/lib/src/serde/xml.rs
+++ b/lib/src/serde/xml.rs
@@ -6,38 +6,38 @@ use std::str::FromStr;
 use uuid::Uuid;
 
 #[derive(Serialize, Deserialize, Debug)]
-pub enum AppType {
+pub enum ProjectType {
     App,
     Library,
 }
 
-impl Default for AppType {
+impl Default for ProjectType {
     fn default() -> Self {
         Self::App
     }
 }
 
 #[derive(Serialize, Deserialize, Debug)]
-pub struct Application {
+pub struct Project {
     #[serde(default, rename = "pou-list")]
     pub pou_list: POUList,
     #[serde(rename = "@name")]
     pub name: String,
     #[serde(rename = "@type", default)]
-    pub app_type: AppType,
+    pub project_type: ProjectType,
     #[serde(rename = "@namespace")]
     pub namespace: Option<String>,
 }
 
-impl From<Application> for ModuleContext {
-    fn from(app: Application) -> Self {
-        let ctx = match app.app_type {
-            AppType::App => ModuleContext::new(ModuleKind::Application),
-            AppType::Library => ModuleContext::new(ModuleKind::Library),
+impl From<Project> for ModuleContext {
+    fn from(proj: Project) -> Self {
+        let ctx = match proj.project_type {
+            ProjectType::App => ModuleContext::new(ModuleKind::Application),
+            ProjectType::Library => ModuleContext::new(ModuleKind::Library),
         };
         let mut ctx_write = ctx.write();
 
-        for pou in app.pou_list.pou {
+        for pou in proj.pou_list.pou {
             let mut lexer = StLexerBuilder::new().build_str(&pou.interface.content);
             let decl = ParserBuilder::default().build().parse(&mut lexer).unwrap();
             let func = ctx_write.add_declaration(
diff --git a/lib/src/test/test_type_analyze.rs b/lib/src/test/test_type_analyze.rs
index 93c32e0..de6fa6d 100644
--- a/lib/src/test/test_type_analyze.rs
+++ b/lib/src/test/test_type_analyze.rs
@@ -1,24 +1,21 @@
+use crate::analysis::TypeAnalyzer;
+use crate::parse_statement;
 use crate::parser::{ParserBuilder, StLexerBuilder};
 use crate::prelude::*;
-use crate::serde::Application;
-
-use crate::analysis::TypeAnalyzer;
+use crate::serde::Project;
 use quick_xml::de::from_str;
 
 #[test]
 fn test_type_analyze() {
-    let app: Application = from_str(include_str!("test_projects/test_proj1.xml")).unwrap();
-    let mgr = UnitsManager::new();
+    let app: Project = from_str(include_str!("test_projects/test_proj1.xml")).unwrap();
     let ctx: ModuleContext = app.into();
+
+    let mgr = UnitsManager::new();
     let ctx_id = ctx.read().id();
     mgr.write().add_context(ctx.clone());
     mgr.write().set_active_application(Some(ctx.read().id()));
 
-    let stmt_str = "c := a + b;";
-    let mut lexer = StLexerBuilder::new().build_str(stmt_str);
-    let parser = ParserBuilder::default().build();
-    let mut stmt = parser.parse_stmt(&mut lexer).unwrap();
-
+    let mut stmt = parse_statement!("c := a + b;").unwrap();
     let mut type_analyzer = TypeAnalyzer::new();
     type_analyzer.analyze_statement(&mut stmt, mgr.module_scope(ctx_id));
 
diff --git a/lib/src/utils/hasher.rs b/lib/src/utils/hasher.rs
index a045d2c..cb799ea 100644
--- a/lib/src/utils/hasher.rs
+++ b/lib/src/utils/hasher.rs
@@ -46,7 +46,8 @@ impl MyHash for Variable {
 
 impl MyHash for Type {
     fn hash<H: Hasher>(&self, state: &mut H) {
-        todo!()
+        // TODO: incomplete implements
+        self.type_class().hash(state);
     }
 }
 
@@ -115,12 +116,16 @@ impl<H: Hasher> DeclVisitor<'_> for AstHasher<H> {
 impl<H: Hasher> AstVisitor<'_> for AstHasher<H> {
     fn visit_literal(&mut self, literal: &LiteralExpression) {
         VisitType::Literal.hash(&mut self.hasher);
-        literal.literal().hash(&mut self.hasher)
+        literal.literal().hash(&mut self.hasher);
+        literal.literal().ty().hash(&mut self.hasher);
     }
 
     fn visit_variable_expression(&mut self, variable: &'_ VariableExpression) {
         VisitType::Variable.hash(&mut self.hasher);
-        variable.name().hash(&mut self.hasher)
+        variable.name().hash(&mut self.hasher);
+        if let Some(ty) = variable.ty() {
+            ty.hash(&mut self.hasher);
+        }
     }
 
     fn visit_expr_statement(&mut self, stmt: &ExprStatement) {
diff --git a/screenshots/Screenshot_20231209_230838.png b/screenshots/Screenshot_20231209_230838.png
index 8a25c9e..052f945 100644
Binary files a/screenshots/Screenshot_20231209_230838.png and b/screenshots/Screenshot_20231209_230838.png differ
diff --git a/viewer/src/app.rs b/viewer/src/app.rs
index 0d3ff54..d4e5ff9 100644
--- a/viewer/src/app.rs
+++ b/viewer/src/app.rs
@@ -1,7 +1,7 @@
 use stc::analysis::TypeAnalyzer;
 use stc::backend::{CodeGenBackend, CodeGenDriver, LuaBackend};
 use stc::prelude::*;
-use stc::serde::Application;
+use stc::serde::Project;
 use stc::utils::write_ast_to_file;
 
 use log::info;
@@ -21,7 +21,7 @@ impl StcViewerApp {
     }
 
     #[inline]
-    pub fn from_app(app: Application) -> Self {
+    pub fn from_app(app: Project) -> Self {
         let mgr = UnitsManager::new();
         let ctx: ModuleContext = app.into();
         mgr.write().add_context(ctx.clone());