Naming Numbers

Mix.install([
  {:jason, "~> 1.4"},
  {:kino, "~> 0.8.0", override: true},
  {:youtube, github: "brooklinjazz/youtube"},
  {:hidden_cell, github: "brooklinjazz/hidden_cell"}
])

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Setup

Ensure you type the ea keyboard shortcut to evaluate all Elixir cells before starting. Alternatively you can evaluate the Elixir cells as you read.

Naming Numbers

In the Elixir cell below, create a function naming_numbers which accepts a single digit integer and returns its string representation. So 1 would become "one".

flowchart
   0 --> zero
   1 --> one
   2 --> two
   3 --> three
   4 --> four
   5 --> five
   6 --> six
   7 --> seven
   8 --> eight
   9 --> nine

naming_numbers.(1)
"one"

Solution Example

  naming_numbers = fn integer ->
    case integer do
      0 -> "zero"
      1 -> "one"
      2 -> "two"
      3 -> "three"
      4 -> "four"
      5 -> "five"
      6 -> "six"
      7 -> "seven"
      8 -> "eight"
      9 -> "nine"
    end
  end

Enter your solution below.

Numbering Names

In the Elixir cell below, create a function numbering_names which accepts a number’s name and returns its string representation. So "one" would become 1.

In addition to accepting lowercase name, also accept uppercase names so "One" would become 1.

flowchart
  zero --> 0
  one --> 1
  two --> 2
  three --> 3
  four --> 4
  five --> 5
  six --> 6
  seven --> 7
  eight --> 8
  nine --> 9

flowchart
  Zero --> 0
  One --> 1
  Two --> 2
  Three --> 3
  Four --> 4
  Five --> 5
  Six --> 6
  Seven --> 7
  Eight --> 8
  Nine --> 9

Solution Example

We can brute force the solutione using case.

  numbering_names = fn int_str ->
    case int_str do
      "zero" -> 0
      "one" -> 1
      "two" -> 2
      "three" -> 3
      "four" -> 4
      "five" -> 5
      "six" -> 6
      "seven" -> 7
      "eight" -> 8
      "nine" -> 9
      "Zero" -> 0
      "One" -> 1
      "Two" -> 2
      "Three" -> 3
      "Four" -> 4
      "Five" -> 5
      "Six" -> 6
      "Seven" -> 7
      "Eight" -> 8
      "Nine" -> 9
    end
  end

Or use String.downcase/2 to make the solutione more concise. This has the added benefit of handling mixed case such as "ZeRO".

  numbering_names = fn int_str ->
    case String.downcase(int_str) do
      "zero" -> 0
      "one" -> 1
      "two" -> 2
      "three" -> 3
      "four" -> 4
      "five" -> 5
      "six" -> 6
      "seven" -> 7
      "eight" -> 8
      "nine" -> 9
    end
  end

Mark As Completed

file_name = Path.basename(Regex.replace(~r/#.+/, __ENV__.file, ""), ".livemd")

save_name =
  case Path.basename(__DIR__) do
    "reading" -> "naming_numbers_reading"
    "exercises" -> "naming_numbers_exercise"
  end

progress_path = __DIR__ <> "/../progress.json"
existing_progress = File.read!(progress_path) |> Jason.decode!()

default = Map.get(existing_progress, save_name, false)

form =
  Kino.Control.form(
    [
      completed: input = Kino.Input.checkbox("Mark As Completed", default: default)
    ],
    report_changes: true
  )

Task.async(fn ->
  for %{data: %{completed: completed}} <- Kino.Control.stream(form) do
    File.write!(
      progress_path,
      Jason.encode!(Map.put(existing_progress, save_name, completed), pretty: true)
    )
  end
end)

form

Commit Your Progress

Run the following in your command line from the curriculum folder to track and save your progress in a Git commit. Ensure that you do not already have undesired or unrelated changes by running git status or by checking the source control tab in Visual Studio Code.

$ git checkout -b naming-numbers-exercise
$ git add .
$ git commit -m "finish naming numbers exercise"
$ git push origin naming-numbers-exercise

Create a pull request from your naming-numbers-exercise branch to your solutions branch. Please do not create a pull request to the DockYard Academy repository as this will spam our PR tracker.

DockYard Academy Students Only:

Notify your teacher by including @BrooklinJazz in your PR description to get feedback. You (or your teacher) may merge your PR into your solutions branch after review.

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