High Score

# If the key is an atom:
%{atom_key: 1}

# If the key is a different type:
%{1 => :atom_value}

# You can even mix these if the atom form comes second:
%{"first_form" => :a, atom_form: :b}

defmodule Example do
  # Defines the attribute as the value 1
  @constant_number 1

  def example_value() do
    # Returns the value 1
    @constant_number
  end
end

Instructions

In this exercise, you're implementing a way to keep track of the high scores for the most popular game in your local arcade hall.

1. Define a new high score map

To make a new high score map, define the HighScore.new/0 function which doesn't take any arguments and returns a new, empty map of high scores.

HighScore.new()
# => %{}

2. Add players to the high score map

To add a player to the high score map, define HighScore.add_player/3, which is a function which takes 3 arguments:

• The first argument is the map of scores.
• The second argument is the name of a player as a string.
• The third argument is the score as an integer. The argument is optional, implement the third argument with a default value of 0.

Store the default initial score in a module attribute. It will be needed again.

score_map = HighScore.new()
# => %{}
score_map = HighScore.add_player(score_map, "Dave Thomas")
# => %{"Dave Thomas" => 0}
score_map = HighScore.add_player(score_map, "José Valim", 486_373)
# => %{"Dave Thomas" => 0, "José Valim"=> 486_373}

3. Remove players from the score map

To remove a player from the high score map, define HighScore.remove_player/2, which takes 2 arguments:

• The first argument is the map of scores.
• The second argument is the name of the player as a string.

score_map = HighScore.new()
# => %{}
score_map = HighScore.add_player(score_map, "Dave Thomas")
# => %{"Dave Thomas" => 0}
score_map = HighScore.remove_player(score_map, "Dave Thomas")
# => %{}

4. Reset a player's score

To reset a player's score, define HighScore.reset_score/2, which takes 2 arguments:

• The first argument is the map of scores.
• The second argument is the name of the player as a string, whose score you wish to reset.

The function should also work if the player doesn't have a score.

score_map = HighScore.new()
# => %{}
score_map = HighScore.add_player(score_map, "José Valim", 486_373)
# => %{"José Valim"=> 486_373}
score_map = HighScore.reset_score(score_map, "José Valim")
# => %{"José Valim"=> 0}

5. Update a player's score

To update a player's score by adding to the previous score, define HighScore.update_score/3, which takes 3 arguments:

• The first argument is the map of scores.
• The second argument is the name of the player as a string, whose score you wish to update.
• The third argument is the score that you wish to add to the stored high score.

The function should also work if the player doesn't have a previous score - assume the previous score is 0.

score_map = HighScore.new()
# => %{}
score_map = HighScore.add_player(score_map, "José Valim", 486_373)
# => %{"José Valim"=> 486_373}
score_map = HighScore.update_score(score_map, "José Valim", 5)
# => %{"José Valim"=> 486_378}

6. Get a list of players

To get a list of players, define HighScore.get_players/1, which takes 1 argument:

• The first argument is the map of scores.

score_map = HighScore.new()
# => %{}
score_map = HighScore.add_player(score_map, "Dave Thomas", 2_374)
# => %{"Dave Thomas" => 2_374}
score_map = HighScore.add_player(score_map, "José Valim", 486_373)
# => %{"Dave Thomas" => 2_374, "José Valim"=> 486_373}
HighScore.get_players(score_map)
# => ["Dave Thomas", "José Valim"]