Function: List Tasks by Status

Part of the Introduction To Luau section of Coddy's Lua journey. Lesson 48 of 73.

Challenge

Easy

Your editor already contains the Task type, the tasks array, addTask and completeTask from the previous lessons.

Create a function named filterTasks that takes two parameters:

list of type {Task}
done of type boolean

The function should build and return a new array of type {Task} containing only the tasks whose done flag equals the parameter.

Then:

store filterTasks(tasks, false) in pending and filterTasks(tasks, true) in finished
print #pending, then each pending task's title on its own line (use ipairs)
print #finished, then each finished task's title on its own line

Try it yourself

-- The shape every task in the manager must follow
type Task = {
    id: number,
    title: string,
    done: boolean,
}

-- The task list: a typed array of Task shapes
local tasks: {Task} = {
    {id = 1, title = "Learn Luau types", done = false},
    {id = 2, title = "Build a task manager", done = false},
    {id = 3, title = "Write tests", done = true},
}

-- Build a typed task with the next free id and insert it
local function addTask(list: {Task}, title: string): Task
    local newTask: Task = {
        id = #list + 1,
        title = title,
        done = false,
    }
    table.insert(list, newTask)
    return newTask
end

-- Mark the task with the given id as done; report success
local function completeTask(list: {Task}, id: number): boolean
    for _, t in ipairs(list) do
        if t.id == id then
            t.done = true
            return true
        end
    end
    return false
end

-- Complete task 1, then try an id that doesn't exist
print(tasks[1].done)
print(completeTask(tasks, 1))
print(tasks[1].done)
print(completeTask(tasks, 99))