diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
index ddbfb52b..c17963f7 100644
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -87,6 +87,7 @@ add_library(compiler_lib
         ast/ForIter.cpp
         ast/While.cpp
         ast/AssignationOperator.cpp
+        ast/AbstractType.cpp
         # === Environment ===
         environment/Environment.cpp
         environment/Name.cpp
diff --git a/src/lib/ast/AST.h b/src/lib/ast/AST.h
index 83cb75cd..2e466209 100644
--- a/src/lib/ast/AST.h
+++ b/src/lib/ast/AST.h
@@ -200,16 +200,18 @@ namespace filc::ast {
 
         AbstractType(AbstractType &&other) = default;
 
-        auto operator=(const AbstractType &other) -> AbstractType & = default;
+        auto operator=(const AbstractType &other) -> AbstractType & = delete;
 
-        auto operator=(AbstractType &&other) -> AbstractType & = default;
+        auto operator=(AbstractType &&other) -> AbstractType & = delete;
 
         [[nodiscard]] virtual auto dump() const -> std::string = 0;
 
         [[nodiscard]] virtual auto getInnerType() const -> AbstractType * = 0;
 
+        [[nodiscard]] virtual auto equals(const AbstractType &other) const -> bool = 0;
+
     protected:
-        AbstractType() = default;
+        explicit AbstractType() = default;
     };
 
     class Type : public AbstractType {
@@ -224,6 +226,8 @@ namespace filc::ast {
 
         [[nodiscard]] auto getInnerType() const -> AbstractType * override;
 
+        [[nodiscard]] auto equals(const AbstractType &other) const -> bool override;
+
     private:
         Identifier *_name;
     };
@@ -240,6 +244,8 @@ namespace filc::ast {
 
         [[nodiscard]] auto dump() const -> std::string override;
 
+        auto equals(const AbstractType &other) const -> bool override;
+
     private:
         AbstractType *_inner_type;
         unsigned int _size;
@@ -255,6 +261,8 @@ namespace filc::ast {
 
         [[nodiscard]] auto dump() const -> std::string override;
 
+        auto equals(const AbstractType &other) const -> bool override;
+
     private:
         AbstractType *_inner_type;
     };
@@ -276,6 +284,8 @@ namespace filc::ast {
 
         [[nodiscard]] auto getCalledOn() const -> AbstractType *;
 
+        auto equals(const AbstractType &other) const -> bool override;
+
     private:
         std::vector<AbstractType *> _argument_types;
         AbstractType *_return_type;
@@ -632,4 +642,8 @@ namespace filc::ast {
     };
 }
 
+auto operator==(const filc::ast::AbstractType &type1, const filc::ast::AbstractType &type2) -> bool;
+
+auto operator!=(const filc::ast::AbstractType &type1, const filc::ast::AbstractType &type2) -> bool;
+
 #endif //FILC_AST_H
diff --git a/src/lib/ast/AbstractType.cpp b/src/lib/ast/AbstractType.cpp
new file mode 100644
index 00000000..e18cb6a4
--- /dev/null
+++ b/src/lib/ast/AbstractType.cpp
@@ -0,0 +1,32 @@
+/**
+ * MIT License
+ *
+ * Copyright (c) 2023-Present Kevin Traini
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "AST.h"
+
+auto operator==(const filc::ast::AbstractType &type1, const filc::ast::AbstractType &type2) -> bool {
+    return type1.equals(type2);
+}
+
+auto operator!=(const filc::ast::AbstractType &type1, const filc::ast::AbstractType &type2) -> bool {
+    return !(type1 == type2);
+}
\ No newline at end of file
diff --git a/src/lib/ast/ArrayType.cpp b/src/lib/ast/ArrayType.cpp
index 12a6d855..30e4e621 100644
--- a/src/lib/ast/ArrayType.cpp
+++ b/src/lib/ast/ArrayType.cpp
@@ -40,6 +40,19 @@ namespace filc::ast {
     }
 
     ArrayType::~ArrayType() {
-        delete _inner_type;
+//        delete _inner_type;
+    }
+
+    auto ArrayType::equals(const AbstractType &other) const -> bool {
+        if (dynamic_cast<const ArrayType *>(&other) == nullptr) {
+            return false;
+        }
+        auto other_type = dynamic_cast<const ArrayType &>(other);
+
+        if (_size != other_type._size) {
+            return false;
+        }
+
+        return *_inner_type == *other_type._inner_type;
     }
 }
diff --git a/src/lib/ast/ClassicOperator.cpp b/src/lib/ast/ClassicOperator.cpp
index 9672fe34..11a935c1 100644
--- a/src/lib/ast/ClassicOperator.cpp
+++ b/src/lib/ast/ClassicOperator.cpp
@@ -80,7 +80,7 @@ namespace filc::ast {
                                             filc::ast::AbstractType *called_on,
                                             filc::environment::Environment *environment,
                                             filc::message::MessageCollector *collector) const -> LambdaType * {
-        return new LambdaType({}, return_type);
+        return new LambdaType({}, return_type, called_on);
     }
 
     auto ClassicOperator::dumpPostLambdaType(filc::ast::AbstractType *return_type,
diff --git a/src/lib/ast/LambdaType.cpp b/src/lib/ast/LambdaType.cpp
index 13b6fe49..e7ae0417 100644
--- a/src/lib/ast/LambdaType.cpp
+++ b/src/lib/ast/LambdaType.cpp
@@ -54,10 +54,10 @@ namespace filc::ast {
     }
 
     LambdaType::~LambdaType() {
-        for (const auto &argument_type: _argument_types) {
-            delete argument_type;
-        }
-        delete _return_type;
+//        for (const auto &argument_type: _argument_types) {
+//            delete argument_type;
+//        }
+//        delete _return_type;
     }
 
     auto LambdaType::getInnerType() const -> AbstractType * {
@@ -67,4 +67,23 @@ namespace filc::ast {
     auto LambdaType::getCalledOn() const -> AbstractType * {
         return _called_on;
     }
+
+    auto LambdaType::equals(const AbstractType &other) const -> bool {
+        if (dynamic_cast<const LambdaType *>(&other) == nullptr) {
+            return false;
+        }
+        auto other_type = dynamic_cast<const LambdaType &>(other);
+
+        if (_argument_types.size() != other_type._argument_types.size()) {
+            return false;
+        }
+
+        for (unsigned int i = 0; i < _argument_types.size(); i++) {
+            if (*_argument_types[i] != *other_type._argument_types[i]) {
+                return false;
+            }
+        }
+
+        return *_return_type == *other_type._return_type && *_called_on == *other_type._called_on;
+    }
 }
diff --git a/src/lib/ast/PointerType.cpp b/src/lib/ast/PointerType.cpp
index 90161e71..c6c49b23 100644
--- a/src/lib/ast/PointerType.cpp
+++ b/src/lib/ast/PointerType.cpp
@@ -36,6 +36,15 @@ namespace filc::ast {
     }
 
     PointerType::~PointerType() {
-        delete _inner_type;
+//        delete _inner_type;
+    }
+
+    auto PointerType::equals(const AbstractType &other) const -> bool {
+        if (dynamic_cast<const PointerType *>(&other) == nullptr) {
+            return false;
+        }
+        auto other_type = dynamic_cast<const PointerType &>(other);
+
+        return *_inner_type == *other_type._inner_type;
     }
 }
diff --git a/src/lib/ast/Type.cpp b/src/lib/ast/Type.cpp
index 6608a0d7..4e314954 100644
--- a/src/lib/ast/Type.cpp
+++ b/src/lib/ast/Type.cpp
@@ -28,7 +28,7 @@ namespace filc::ast {
             : _name(name) {}
 
     Type::~Type() {
-        delete _name;
+//        delete _name;
     }
 
     auto Type::getName() const -> Identifier * {
@@ -42,4 +42,13 @@ namespace filc::ast {
     auto Type::getInnerType() const -> AbstractType * {
         return (AbstractType *) this;
     }
+
+    auto Type::equals(const AbstractType &other) const -> bool {
+        if (dynamic_cast<const Type *>(&other) == nullptr) {
+            return false;
+        }
+        auto other_type = dynamic_cast<const Type &>(other);
+
+        return _name->getName() == other_type._name->getName();
+    }
 }
\ No newline at end of file
diff --git a/src/lib/ast/VariableDeclaration.cpp b/src/lib/ast/VariableDeclaration.cpp
index 8bd7642e..3a815f6c 100644
--- a/src/lib/ast/VariableDeclaration.cpp
+++ b/src/lib/ast/VariableDeclaration.cpp
@@ -71,7 +71,8 @@ namespace filc::ast {
             return;
         }
 
-        if (environment->getName("operator=", new filc::ast::LambdaType({_type, assignation_type}, _type)) == nullptr) {
+        if (!environment->hasName("operator=", new filc::ast::LambdaType({_type, assignation_type},
+                                                                         environment->getType("void")))) {
             collector->addError(
                     new filc::message::Error(filc::message::ERROR,
                                              "Cannot assign " + assignation_type->dump() + " to " + _type->dump(),
diff --git a/src/lib/environment/Environment.cpp b/src/lib/environment/Environment.cpp
index f4c2ffbe..095a2452 100644
--- a/src/lib/environment/Environment.cpp
+++ b/src/lib/environment/Environment.cpp
@@ -35,7 +35,7 @@ namespace filc::environment {
 
     auto Environment::hasName(const std::string &name, filc::ast::AbstractType *type) const -> bool {
         return std::any_of(_names.begin(), _names.end(), [name, type](auto *item) -> bool {
-            return item->getName() == name && (type == nullptr || item->getType()->dump() == type->dump());
+            return item->getName() == name && (type == nullptr || *item->getType() == *type);
         }) || (_parent != nullptr && _parent->hasName(name));
     }
 
@@ -52,7 +52,7 @@ namespace filc::environment {
     auto Environment::getName(const std::string &name, filc::ast::AbstractType *type) const -> Name * {
         if (hasName(name, type)) {
             auto result = std::find_if(_names.begin(), _names.end(), [name, type](auto *item) -> bool {
-                return item->getName() == name && (type == nullptr || item->getType()->dump() == type->dump());
+                return item->getName() == name && (type == nullptr || *item->getType() == *type);
             });
 
             if (result == _names.end()) {