[Example] New example for jac coding manual

examples/manual_code/to_do_ex/note.md

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+# Python vs. Jac: A Comparative Overview
+
+This code examples in both Python and Jac to illustrate the differences between the two languages. The primary focus is on the following features:
+
+1.  Curly Braces Back
+2.  Keyword Changes (def → can)
+3.  DocString Discipline
+4.  Explicit Tuples
+5.  Dataclass Style Basis for OOP
+6.  No Gratuitous Self Usage
+7.  Variable Reference
+8.  Enumeration
+
+- Python implementation - [to_do.py](/examples/manual_code/to_do_ex/to_do.py)
+- Jac basic implementation - [to_do.jac](/examples/manual_code/to_do_ex/to_do_v1.jac)

examples/manual_code/to_do_ex/to_do.py

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+import datetime
+
+# Enum for task status
+from enum import Enum
+
+
+class TaskStatus(Enum):
+    PENDING = "Pending"
+    COMPLETED = "Completed"
+
+
+# Dataclass style for a Task
+class Task:
+    def __init__(self, description, status=TaskStatus.PENDING):
+        """
+        Initialize a task.
+
+        Arguments:
+        description -- description of the task
+        status -- status of the task (Pending, Completed)
+        """
+        self.description = description
+        self.status = status
+        self.created_at = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+
+
+# Dataclass style for the ToDoList
+class ToDoList:
+    def __init__(self):
+        """
+        Initialize the to-do list.
+        """
+        self.tasks = []
+
+    def add_task(self, description):
+        """
+        Add a task to the to-do list.
+        Arguments:
+        description -- description of the task
+        """
+        self.tasks.append(Task(description))
+
+    def view_tasks(self):
+        """
+        View all tasks in the to-do list.
+        """
+        for i, task in enumerate(self.tasks):
+            print(
+                f"{i+1}. {task.description} [{task.status.value}] (Created at: {task.created_at})"
+            )
+
+    def mark_completed(self, index):
+        """
+        Mark a task as completed.
+        Arguments:
+        index -- index of the task to mark as completed
+        """
+        if index < 0 or index >= len(self.tasks):
+            print("Invalid task number!")
+            return
+        self.tasks[index].status = TaskStatus.COMPLETED
+
+
+# Function to display menu
+def display_menu():
+    """
+    Display the menu options.
+    """
+    print("To-Do List Menu:")
+    print("1. Add Task")
+    print("2. View Tasks")
+    print("3. Mark Task as Completed")
+    print("4. Exit")
+
+
+# Function to handle user input
+def handle_input():
+    """
+    Handle user input for menu options.
+    """
+    to_do_list = ToDoList()
+    while True:
+        display_menu()
+        choice = input("Enter your choice (1-4): ") or "4"
+        if choice == "1":
+            description = input("Enter task description: ") or ""
+            to_do_list.add_task(description)
+        elif choice == "2":
+            to_do_list.view_tasks()
+        elif choice == "3":
+            index = int(input("Enter task number to mark as completed: ") or "-1") - 1
+            to_do_list.mark_completed(index)
+        elif choice == "4":
+            print("Exiting...")
+            break
+        else:
+            print("Invalid choice! Please enter a number between 1 and 4.")
+
+
+# Entry point of the app
+if __name__ == "__main__":
+    handle_input()
+
+# # Unit Tests
+# def test_add_task():
+#     to_do_list = ToDoList()
+#     to_do_list.add_task("Test Task")
+#     assert len(to_do_list.tasks) == 1
+#     assert to_do_list.tasks[0].description == "Test Task"
+
+# def test_mark_completed():
+#     to_do_list = ToDoList()
+#     to_do_list.add_task("Test Task")
+#     to_do_list.mark_completed(0)
+#     assert to_do_list.tasks[0].status == TaskStatus.COMPLETED
+
+# def test_invalid_task_number():
+#     to_do_list = ToDoList()
+#     to_do_list.add_task("Test Task")
+#     to_do_list.mark_completed(1)
+#     assert to_do_list.tasks[0].status == TaskStatus.PENDING
+
+# # Running unit tests
+# test_add_task()
+# test_mark_completed()
+# test_invalid_task_number()
+# print("All tests passed.")

examples/manual_code/to_do_ex/to_do_v1.jac

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+import:py datetime;
+import:py from enum { Enum }
+import:py from random { randint }
+
+enum TaskStatus {
+    PENDING = "Pending",
+    COMPLETED = "Completed"
+}
+
+"""
+Initialize a task.
+description -- description of the task
+status -- status of the task (Pending, Completed)
+"""
+obj Task {
+    has description: str;
+    has status: TaskStatus = TaskStatus.PENDING;
+    has created_at: datetime = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S");
+}
+
+"""Initialize the to-do list."""
+obj ToDoList {
+    has tasks: list = [];
+
+    can add_task(description: str) {
+        self.tasks.append(Task(description));
+    }
+
+    can view_tasks() {
+        if self.tasks {
+            for (i, task) in enumerate(self.tasks) {
+                print(
+                    f"{(i + 1)}{". "}{task.description}{" ["}{task.status.value}{"] (Created at: "}{task.created_at}{")"}"
+                );
+            }
+        } else {
+            print("No tasks");
+        }
+    }
+
+    can mark_completed(index: int) {
+        if index < 0 or index >= len(self.tasks) {
+            print("Invalid task number!");
+        }
+        self.tasks[index].status = TaskStatus.COMPLETED;
+    }
+}
+
+can display_menu() {
+    print("To-Do List Menu:");
+    print("1. Add Task");
+    print("2. View Tasks");
+    print("3. Mark Task as Completed");
+    print("4. Exit");
+}
+
+can handle_input() {
+    to_do_list = ToDoList();
+
+    while True {
+        display_menu();
+        choice = input("Enter your choice (1-4): ") or "4";
+        if choice == "1" {
+            description = input("Enter task description: ") or "";
+            to_do_list.add_task(description);
+        } elif choice == "2" {
+            to_do_list.view_tasks();
+        } elif choice == "3" {
+            index = (int(
+                input("Enter task number to mark as completed: ")
+                    or "-1"
+            ) - 1);
+            to_do_list.mark_completed(index);
+        } elif choice == "4" {
+            print("Exiting...");
+            break;
+        } else {
+            print(
+                "Invalid choice! Please enter a number between 1 and 4."
+            );
+        }
+    }
+}
+# can test_add_task() {
+#     to_do_list = ToDoList();
+#     to_do_list.add_task("Test Task");
+#     assert len(to_do_list.tasks) == 1;
+#     assert to_do_list.tasks[0].description == "Test Task";
+# }
+# can test_mark_completed() {
+#     to_do_list = ToDoList();
+#     to_do_list.add_task("Test Task");
+#     to_do_list.mark_completed(0);
+#     assert to_do_list.tasks[0].status == TaskStatus.COMPLETED;
+# }
+# can test_invalid_task_number() {
+#     to_do_list = ToDoList();
+#     to_do_list.add_task("Test Task");
+#     to_do_list.mark_completed(1);
+#     assert to_do_list.tasks[0].status == TaskStatus.PENDING;
+# }
+
+with entry {
+    handle_input();
+}