diff --git a/examples/main.bl b/examples/main.bl
index 6b86a2f..6a417ed 100644
--- a/examples/main.bl
+++ b/examples/main.bl
@@ -65,6 +65,10 @@ impl User {
     }
 }
 
+fn main(): i64 {
+  add(4, 4)
+}
+
 // type TestTrait trait {
 //     fn classMethod(id: i64): Self;
 //     fn instanceMethod(self: Self): i64;
diff --git a/src/interpreter.rs b/src/interpreter.rs
new file mode 100644
index 0000000..155b57f
--- /dev/null
+++ b/src/interpreter.rs
@@ -0,0 +1,682 @@
+use crate::ast;
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
+
+#[derive(Debug, Clone)]
+pub enum NumericValue {
+    I8(i8),
+    I16(i16),
+    I32(i32),
+    I64(i64),
+    ISize(isize),
+
+    U8(u8),
+    U16(u16),
+    U32(u32),
+    U64(u64),
+    USize(usize),
+
+    F32(f32),
+    F64(f64),
+}
+
+#[derive(Debug, Clone)]
+pub struct StructValue {
+    source: ast::StructTypeDeclaration,
+    fields: HashMap<String, Value>,
+}
+
+type BuiltinFunction = fn(Vec<Value>) -> Value;
+
+#[derive(Debug, Clone)]
+pub enum Function {
+    User(ast::Function),
+    Builtin(BuiltinFunction),
+}
+
+#[derive(Debug, Clone)]
+pub enum Value {
+    Numeric(NumericValue),
+    Function(Function),
+    Struct(Arc<Mutex<StructValue>>),
+    Unit,
+}
+
+#[derive(Debug, Clone)]
+pub enum NamedEntity {
+    TypeDeclaration(ast::TypeDeclaration),
+    Variable(Value),
+}
+
+#[derive(Debug, Clone)]
+struct Context {
+    pub environment: HashMap<String, NamedEntity>,
+    pub impls: HashMap<String, ast::Impl>,
+    pub current_module: ast::Module,
+}
+
+impl Context {
+    fn set_variable(&mut self, name: String, value: &Value) {
+        self.environment
+            .insert(name.to_string(), NamedEntity::Variable(value.clone()));
+    }
+
+    fn new_env(&self) -> Context {
+        return Context::from_module(&self.current_module);
+    }
+
+    fn from_module(module: &ast::Module) -> Context {
+        let mut ctx = Context {
+            environment: create_builtins(),
+            impls: HashMap::new(),
+            current_module: module.clone(),
+        };
+
+        for item in ctx.current_module.items.iter() {
+            match item {
+                ast::ModuleItem::TypeDeclaration(ast::TypeDeclaration::Struct(struct_)) => {
+                    ctx.environment.insert(
+                        struct_.name.name.value.to_string(),
+                        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Struct(struct_.clone())),
+                    );
+                }
+                ast::ModuleItem::TypeDeclaration(ast::TypeDeclaration::Alias(alias)) => {
+                    ctx.environment.insert(
+                        alias.name.name.value.to_string(),
+                        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Alias(alias.clone())),
+                    );
+                }
+                ast::ModuleItem::Function(function) => {
+                    ctx.environment.insert(
+                        function.declaration.name.name.value.to_string(),
+                        NamedEntity::Variable(Value::Function(Function::User(function.clone()))),
+                    );
+                }
+                ast::ModuleItem::Impl(impl_) => {
+                    ctx.impls
+                        .insert(impl_.struct_name.name.value.to_string(), impl_.clone());
+                }
+                _ => {}
+            }
+        }
+        return ctx;
+    }
+}
+
+fn create_builtins() -> HashMap<String, NamedEntity> {
+    let mut result = HashMap::new();
+    result.insert(
+        "i8".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "i8".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "i16".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "i16".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "i32".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "i32".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "i64".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "i64".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "isize".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "isize".to_string(),
+            },
+        )),
+    );
+
+    result.insert(
+        "u8".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "u8".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "u16".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "u16".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "u32".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "u32".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "u64".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "u64".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "usize".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "usize".to_string(),
+            },
+        )),
+    );
+
+    result.insert(
+        "f32".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "f32".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "f64".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "f64".to_string(),
+            },
+        )),
+    );
+
+    result.insert(
+        "!".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "!".to_string(),
+            },
+        )),
+    );
+    result.insert(
+        "unit".to_string(),
+        NamedEntity::TypeDeclaration(ast::TypeDeclaration::Primitive(
+            ast::PrimitiveTypeDeclaration {
+                name: "!".to_string(),
+            },
+        )),
+    );
+
+    return result;
+}
+
+pub enum ExpressionResult {
+    Value(Value),
+    Return(Value),
+}
+
+pub struct TreeWalkInterpreter {}
+
+impl TreeWalkInterpreter {
+    pub fn with_module(self: &Self, module: &ast::Module) -> Value {
+        let mut ctx = Context::from_module(module);
+
+        let main = match &ctx.environment["main"] {
+            NamedEntity::Variable(Value::Function(Function::User(func))) => func.clone(),
+            _ => panic!("main should be a user defined function"),
+        };
+
+        return self.with_function(&mut ctx, &main);
+    }
+
+    fn with_function(self: &Self, ctx: &mut Context, function: &ast::Function) -> Value {
+        let result = self.with_block(ctx, &function.block);
+        return match result {
+            ExpressionResult::Value(r) => r,
+            ExpressionResult::Return(r) => r,
+        };
+    }
+
+    fn with_block(self: &Self, ctx: &mut Context, block: &ast::Block) -> ExpressionResult {
+        let mut last = ExpressionResult::Value(Value::Unit);
+        for statement in block.statements.iter() {
+            let result = self.with_statement(ctx, statement);
+            match result {
+                ExpressionResult::Return(r) => {
+                    return ExpressionResult::Return(r);
+                }
+                ExpressionResult::Value(r) => {
+                    last = ExpressionResult::Value(r);
+                }
+            }
+        }
+        return last;
+    }
+
+    fn with_statement(
+        self: &Self,
+        ctx: &mut Context,
+        statement: &ast::Statement,
+    ) -> ExpressionResult {
+        match statement {
+            ast::Statement::Return(return_statement) => {
+                let result = match self.with_expression(ctx, &return_statement.source) {
+                    ExpressionResult::Value(r) => r,
+                    ExpressionResult::Return(r) => {
+                        return ExpressionResult::Return(r);
+                    }
+                };
+                return ExpressionResult::Return(result);
+            }
+            ast::Statement::Let(let_statement) => {
+                let result = match self.with_expression(ctx, &let_statement.expression) {
+                    ExpressionResult::Value(r) => r,
+                    ExpressionResult::Return(r) => {
+                        return ExpressionResult::Return(r);
+                    }
+                };
+                ctx.set_variable(let_statement.variable_name.name.value.to_string(), &result);
+                return ExpressionResult::Value(Value::Unit);
+            }
+            ast::Statement::Assignment(assignment_statement) => {
+                return self.with_assignment_statement(ctx, assignment_statement);
+            }
+            ast::Statement::Expression(expression) => {
+                return self.with_expression(ctx, expression);
+            }
+        }
+    }
+
+    fn with_assignment_statement(
+        self: &Self,
+        ctx: &mut Context,
+        statement: &ast::AssignmentStatement,
+    ) -> ExpressionResult {
+        let result = match self.with_expression(ctx, &statement.expression) {
+            ExpressionResult::Value(r) => r,
+            ExpressionResult::Return(r) => {
+                return ExpressionResult::Return(r);
+            }
+        };
+        match &statement.source {
+            ast::AssignmentTarget::Variable(variable) => {
+                ctx.set_variable(variable.name.name.value.to_string(), &result);
+            }
+            ast::AssignmentTarget::StructAttr(struct_attr) => {
+                let mut source = match self.with_expression(ctx, &struct_attr.source) {
+                    ExpressionResult::Value(r) => r,
+                    ExpressionResult::Return(r) => {
+                        return ExpressionResult::Return(r);
+                    }
+                };
+                match &mut source {
+                    Value::Struct(s) => {
+                        let mut struct_ = s.lock().unwrap();
+                        struct_
+                            .fields
+                            .insert(struct_attr.attribute.name.value.clone(), result);
+                    }
+                    _ => panic!("set attr on nonstruct, should never happen due to type system"),
+                }
+            }
+        }
+        return ExpressionResult::Value(Value::Unit);
+    }
+
+    fn with_expression(
+        self: &Self,
+        ctx: &mut Context,
+        expression: &ast::Expression,
+    ) -> ExpressionResult {
+        match &*expression.subexpression {
+            ast::Subexpression::LiteralInt(literal_int) => {
+                let value: i64 = literal_int.value.value.parse().unwrap();
+                return ExpressionResult::Value(Value::Numeric(NumericValue::I64(value)));
+            }
+            ast::Subexpression::LiteralFloat(literal_float) => {
+                let value: f64 = literal_float.value.value.parse().unwrap();
+                return ExpressionResult::Value(Value::Numeric(NumericValue::F64(value)));
+            }
+            ast::Subexpression::LiteralStruct(literal_struct) => {
+                let declaration = match &ctx.environment[&literal_struct.name.name.value] {
+                    NamedEntity::TypeDeclaration(ast::TypeDeclaration::Struct(declaration)) => {
+                        declaration.clone()
+                    }
+                    _ => panic!("not a struct"),
+                };
+
+                let mut fields = HashMap::new();
+                for field in declaration.fields.iter() {
+                    for (field_name, field_expression) in literal_struct.fields.iter() {
+                        if field.name.name.value == field_name.name.value {
+                            let field_result = match self.with_expression(ctx, field_expression) {
+                                ExpressionResult::Value(r) => r,
+                                ExpressionResult::Return(r) => {
+                                    return ExpressionResult::Return(r);
+                                }
+                            };
+                            fields.insert(field.name.name.value.to_string(), field_result);
+                        }
+                    }
+                }
+                return ExpressionResult::Value(Value::Struct(Arc::new(Mutex::new(StructValue {
+                    source: declaration.clone(),
+                    fields: fields,
+                }))));
+            }
+            ast::Subexpression::FunctionCall(function_call) => {
+                let source = match self.with_expression(ctx, &function_call.source) {
+                    ExpressionResult::Value(r) => r,
+                    ExpressionResult::Return(r) => {
+                        return ExpressionResult::Return(r);
+                    }
+                };
+                let mut argument_values = vec![];
+                for arg in function_call.arguments.iter() {
+                    let argument_value = match self.with_expression(ctx, arg) {
+                        ExpressionResult::Value(r) => r,
+                        ExpressionResult::Return(r) => {
+                            return ExpressionResult::Return(r);
+                        }
+                    };
+                    argument_values.push(argument_value);
+                }
+                match &source {
+                    Value::Function(Function::User(user_function)) => {
+                        let mut fn_ctx = ctx.new_env();
+                        for (i, function_arg) in
+                            user_function.declaration.arguments.iter().enumerate()
+                        {
+                            fn_ctx.set_variable(
+                                function_arg.name.name.value.to_string(),
+                                &argument_values[i].clone(),
+                            );
+                        }
+                        return ExpressionResult::Value(
+                            self.with_function(&mut fn_ctx, user_function),
+                        );
+                    }
+                    Value::Function(Function::Builtin(builtin_function)) => {
+                        return ExpressionResult::Value(builtin_function(argument_values));
+                    }
+                    _ => panic!("type error: function call source must be a function"),
+                }
+            }
+            ast::Subexpression::VariableUsage(variable_usage) => {
+                let variable_value = match &ctx.environment[&variable_usage.name.name.value] {
+                    NamedEntity::Variable(v) => v.clone(),
+                    _ => panic!("variable lookup of type"),
+                };
+                return ExpressionResult::Value(variable_value);
+            }
+            ast::Subexpression::StructGetter(struct_getter) => {
+                let source = match self.with_expression(ctx, &struct_getter.source) {
+                    ExpressionResult::Value(r) => r,
+                    ExpressionResult::Return(r) => {
+                        return ExpressionResult::Return(r);
+                    }
+                };
+                match &source {
+                    Value::Struct(struct_) => {
+                        let s = struct_.lock().unwrap();
+                        return ExpressionResult::Value(
+                            s.fields[&struct_getter.attribute.name.value].clone(),
+                        );
+                    }
+                    _ => {
+                        panic!("TypeError: struct getter used with non-struct");
+                    }
+                }
+            }
+            ast::Subexpression::Block(block) => {
+                return self.with_block(ctx, block);
+            }
+            ast::Subexpression::Op(op) => {
+                let left = match self.with_expression(ctx, &op.left) {
+                    ExpressionResult::Value(r) => r,
+                    ExpressionResult::Return(r) => {
+                        return ExpressionResult::Return(r);
+                    }
+                };
+                let right = match self.with_expression(ctx, &op.right) {
+                    ExpressionResult::Value(r) => r,
+                    ExpressionResult::Return(r) => {
+                        return ExpressionResult::Return(r);
+                    }
+                };
+                let result = match (&left, &op.op, &right) {
+                    //I
+                    (
+                        Value::Numeric(NumericValue::I8(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::I8(r)),
+                    ) => Value::Numeric(NumericValue::I8(l + r)),
+                    (
+                        Value::Numeric(NumericValue::I8(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::I8(r)),
+                    ) => Value::Numeric(NumericValue::I8(l - r)),
+                    (
+                        Value::Numeric(NumericValue::I8(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::I8(r)),
+                    ) => Value::Numeric(NumericValue::I8(l * r)),
+                    (
+                        Value::Numeric(NumericValue::I8(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::I8(r)),
+                    ) => Value::Numeric(NumericValue::I8(l / r)),
+
+                    (
+                        Value::Numeric(NumericValue::I16(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::I16(r)),
+                    ) => Value::Numeric(NumericValue::I16(l + r)),
+                    (
+                        Value::Numeric(NumericValue::I16(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::I16(r)),
+                    ) => Value::Numeric(NumericValue::I16(l - r)),
+                    (
+                        Value::Numeric(NumericValue::I16(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::I16(r)),
+                    ) => Value::Numeric(NumericValue::I16(l * r)),
+                    (
+                        Value::Numeric(NumericValue::I16(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::I16(r)),
+                    ) => Value::Numeric(NumericValue::I16(l / r)),
+
+                    (
+                        Value::Numeric(NumericValue::I32(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::I32(r)),
+                    ) => Value::Numeric(NumericValue::I32(l + r)),
+                    (
+                        Value::Numeric(NumericValue::I32(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::I32(r)),
+                    ) => Value::Numeric(NumericValue::I32(l - r)),
+                    (
+                        Value::Numeric(NumericValue::I32(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::I32(r)),
+                    ) => Value::Numeric(NumericValue::I32(l * r)),
+                    (
+                        Value::Numeric(NumericValue::I32(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::I32(r)),
+                    ) => Value::Numeric(NumericValue::I32(l / r)),
+
+                    (
+                        Value::Numeric(NumericValue::I64(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::I64(r)),
+                    ) => Value::Numeric(NumericValue::I64(l + r)),
+                    (
+                        Value::Numeric(NumericValue::I64(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::I64(r)),
+                    ) => Value::Numeric(NumericValue::I64(l - r)),
+                    (
+                        Value::Numeric(NumericValue::I64(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::I64(r)),
+                    ) => Value::Numeric(NumericValue::I64(l * r)),
+                    (
+                        Value::Numeric(NumericValue::I64(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::I64(r)),
+                    ) => Value::Numeric(NumericValue::I64(l / r)),
+
+                    //U
+                    (
+                        Value::Numeric(NumericValue::U8(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::U8(r)),
+                    ) => Value::Numeric(NumericValue::U8(l + r)),
+                    (
+                        Value::Numeric(NumericValue::U8(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::U8(r)),
+                    ) => Value::Numeric(NumericValue::U8(l - r)),
+                    (
+                        Value::Numeric(NumericValue::U8(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::U8(r)),
+                    ) => Value::Numeric(NumericValue::U8(l * r)),
+                    (
+                        Value::Numeric(NumericValue::U8(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::U8(r)),
+                    ) => Value::Numeric(NumericValue::U8(l / r)),
+
+                    (
+                        Value::Numeric(NumericValue::U16(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::U16(r)),
+                    ) => Value::Numeric(NumericValue::U16(l + r)),
+                    (
+                        Value::Numeric(NumericValue::U16(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::U16(r)),
+                    ) => Value::Numeric(NumericValue::U16(l - r)),
+                    (
+                        Value::Numeric(NumericValue::U16(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::U16(r)),
+                    ) => Value::Numeric(NumericValue::U16(l * r)),
+                    (
+                        Value::Numeric(NumericValue::U16(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::U16(r)),
+                    ) => Value::Numeric(NumericValue::U16(l / r)),
+
+                    (
+                        Value::Numeric(NumericValue::U32(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::U32(r)),
+                    ) => Value::Numeric(NumericValue::U32(l + r)),
+                    (
+                        Value::Numeric(NumericValue::U32(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::U32(r)),
+                    ) => Value::Numeric(NumericValue::U32(l - r)),
+                    (
+                        Value::Numeric(NumericValue::U32(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::U32(r)),
+                    ) => Value::Numeric(NumericValue::U32(l * r)),
+                    (
+                        Value::Numeric(NumericValue::U32(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::U32(r)),
+                    ) => Value::Numeric(NumericValue::U32(l / r)),
+
+                    (
+                        Value::Numeric(NumericValue::U64(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::U64(r)),
+                    ) => Value::Numeric(NumericValue::U64(l + r)),
+                    (
+                        Value::Numeric(NumericValue::U64(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::U64(r)),
+                    ) => Value::Numeric(NumericValue::U64(l - r)),
+                    (
+                        Value::Numeric(NumericValue::U64(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::U64(r)),
+                    ) => Value::Numeric(NumericValue::U64(l * r)),
+                    (
+                        Value::Numeric(NumericValue::U64(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::U64(r)),
+                    ) => Value::Numeric(NumericValue::U64(l / r)),
+
+                    //F
+                    (
+                        Value::Numeric(NumericValue::F32(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::F32(r)),
+                    ) => Value::Numeric(NumericValue::F32(l + r)),
+                    (
+                        Value::Numeric(NumericValue::F32(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::F32(r)),
+                    ) => Value::Numeric(NumericValue::F32(l - r)),
+                    (
+                        Value::Numeric(NumericValue::F32(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::F32(r)),
+                    ) => Value::Numeric(NumericValue::F32(l * r)),
+                    (
+                        Value::Numeric(NumericValue::F32(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::F32(r)),
+                    ) => Value::Numeric(NumericValue::F32(l / r)),
+
+                    (
+                        Value::Numeric(NumericValue::F64(l)),
+                        ast::Operator::Plus,
+                        Value::Numeric(NumericValue::F64(r)),
+                    ) => Value::Numeric(NumericValue::F64(l + r)),
+                    (
+                        Value::Numeric(NumericValue::F64(l)),
+                        ast::Operator::Minus,
+                        Value::Numeric(NumericValue::F64(r)),
+                    ) => Value::Numeric(NumericValue::F64(l - r)),
+                    (
+                        Value::Numeric(NumericValue::F64(l)),
+                        ast::Operator::Mul,
+                        Value::Numeric(NumericValue::F64(r)),
+                    ) => Value::Numeric(NumericValue::F64(l * r)),
+                    (
+                        Value::Numeric(NumericValue::F64(l)),
+                        ast::Operator::Div,
+                        Value::Numeric(NumericValue::F64(r)),
+                    ) => Value::Numeric(NumericValue::F64(l / r)),
+
+                    //fail
+                    _ => panic!(""),
+                };
+                return ExpressionResult::Value(result);
+            }
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index ec05ba9..9092c7e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,7 @@
 // mod types;
 mod ast;
 mod errors;
+mod interpreter;
 mod type_alias_resolution;
 mod type_checking;
 #[macro_use]
@@ -64,6 +65,9 @@ fn main() {
         Ok((checked_ast, subst)) => {
             println!("checked ast: {:#?}", &checked_ast);
             println!("substitutions: {:#?}", &subst);
+            let interpreter = interpreter::TreeWalkInterpreter {};
+            let result = interpreter.with_module(&checked_ast);
+            println!("final result: {:#?}", &result);
         }
         Err(err) => {
             println!("type checking error: {:#?}", &err);