91 lines
2.9 KiB
Markdown
91 lines
2.9 KiB
Markdown
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# Pacman Rules
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Welcome to Pacman Rules on Exercism's Elixir Track.
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If you need help running the tests or submitting your code, check out `HELP.md`.
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If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
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## Introduction
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## Booleans
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Elixir represents true and false values with the boolean type. There are only two values: `true` and `false`. These values can be bound to a variable:
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```elixir
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true_variable = true
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false_variable = false
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```
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We can evaluate strict boolean expressions using the `and/2`, `or/2`, and `not/1` operators.
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```elixir
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true_variable = true and true
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false_variable = true and false
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true_variable = false or true
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false_variable = false or false
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true_variable = not false
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false_variable = not true
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```
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When writing a function that returns a boolean value, it is idiomatic to end the function name with a `?`. The same convention can be used for variables that store boolean values.
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```elixir
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def either_true?(a?, b?) do
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a? or b?
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end
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```
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## Instructions
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In this exercise, you need to translate some rules from the classic game Pac-Man into Elixir functions.
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You have four rules to translate, all related to the game states.
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> Don't worry about how the arguments are derived, just focus on combining the arguments to return the intended result.
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## 1. Define if Pac-Man eats a ghost
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Define the `Rules.eat_ghost?/2` function that takes two arguments (_if Pac-Man has a power pellet active_ and _if Pac-Man is touching a ghost_) and returns a boolean value if Pac-Man is able to eat the ghost. The function should return true only if Pac-Man has a power pellet active and is touching a ghost.
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```elixir
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Rules.eat_ghost?(false, true)
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# => false
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```
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## 2. Define if Pac-Man scores
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Define the `Rules.score?/2` function that takes two arguments (_if Pac-Man is touching a power pellet_ and _if Pac-Man is touching a dot_) and returns a boolean value if Pac-Man scored. The function should return true if Pac-Man is touching a power pellet or a dot.
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```elixir
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Rules.score?(true, true)
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# => true
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```
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## 3. Define if Pac-Man loses
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Define the `Rules.lose?/2` function that takes two arguments (_if Pac-Man has a power pellet active_ and _if Pac-Man is touching a ghost_) and returns a boolean value if Pac-Man loses. The function should return true if Pac-Man is touching a ghost and does not have a power pellet active.
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```elixir
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Rules.lose?(false, true)
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# => true
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```
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## 4. Define if Pac-Man wins
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Define the `Rules.win?/3` function that takes three arguments (_if Pac-Man has eaten all of the dots_, _if Pac-Man has a power pellet active_, and _if Pac-Man is touching a ghost_) and returns a boolean value if Pac-Man wins. The function should return true if Pac-Man has eaten all of the dots and has not lost based on the arguments defined in part 3.
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```elixir
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Rules.win?(false, true, false)
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# => false
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```
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## Source
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### Created by
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- @neenjaw
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### Contributed to by
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- @Cohen-Carlisle
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