Function: Print Task Summary

Part of the Introduction To Luau section of Coddy's Lua journey — lesson 49 of 73.

Challenge

Easy

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

Create a function named printSummary that takes one parameter, list of type {Task}, returns nothing (return type ()), and prints one line in the exact format:

{doneCount}/{total} tasks done

where total is #list and doneCount is how many tasks have done == true (count with a loop).

Then exercise the whole toolkit, in this order:

call printSummary(tasks)
call completeTask(tasks, 2)
call printSummary(tasks)
call addTask(tasks, "Take a break")
call printSummary(tasks)

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

-- Collect the tasks whose done flag matches into a new {Task}
local function filterTasks(list: {Task}, done: boolean): {Task}
    local result: {Task} = {}
    for _, t in ipairs(list) do
        if t.done == done then
            table.insert(result, t)
        end
    end
    return result
end

-- Split the list into pending and finished views
local pending: {Task} = filterTasks(tasks, false)
local finished: {Task} = filterTasks(tasks, true)

print(#pending)
for _, t in ipairs(pending) do
    print(t.title)
end

print(#finished)
for _, t in ipairs(finished) do
    print(t.title)
end