Bool type is one of the building blocks of the language.
It aims at describing whether something is true or false, with the respective
Booleans can be combined with the
&& "AND" and the
|| "OR" operators, and negated with the
Booleans are also extremely useful to make branches in your code that only get executed if certain conditions are met.
In Elm, this is done with an
if-then-else expression, used as follows.
if someCondition || (someOtherCondition && anotherCondition) then doSomething else doSomethingElse
In this exercise, you'll be implementing the quest logic for a new RPG game a friend is developing. The game's main character is Annalyn, a brave girl with a fierce and loyal pet dog. Unfortunately, disaster strikes, as her best friend was kidnapped while searching for berries in the forest. Annalyn will try to find and free her best friend, optionally taking her dog with her on this quest.
After some time spent following her best friend's trail, she finds the camp in which her best friend is imprisoned. It turns out there are two kidnappers: a mighty knight and a cunning archer.
Having found the kidnappers, Annalyn considers which of the following actions she can engage in:
You have five tasks: to implement the logic for determining if the above actions are available based on the state of the three characters found in the forest and whether Annalyn's pet dog is present or not.
canFastAttack function that takes a boolean value that indicates if the knight is awake. This function returns
True if a fast attack can be made based on the state of the knight. Otherwise, returns
knightIsAwake = True canFastAttack knightIsAwake --> False
canSpy function that takes three boolean values, indicating if the knight, archer and the prisoner, respectively, are awake. The function returns
True if the group can be spied upon, based on the state of the three characters. Otherwise, returns
knightIsAwake = False archerIsAwake = True prisonerIsAwake = False canSpy knightIsAwake archerIsAwake prisonerIsAwake --> True
canSignalPrisoner function that takes two boolean values, indicating if the archer and the prisoner, respectively, are awake. The function returns
True if the prisoner can be signalled, based on the state of the two characters. Otherwise, returns
archerIsAwake = False prisonerIsAwake = True canSignalPrisoner archerIsAwake prisonerIsAwake --> True
canFreePrisoner function that takes four boolean values. The first three parameters indicate if the knight, archer and the prisoner, respectively, are awake. The last parameter indicates if Annalyn's pet dog is present. The function returns
True if the prisoner can be freed based on the state of the three characters and Annalyn's pet dog presence. Otherwise, it returns
knightIsAwake = False archerIsAwake = True prisonerIsAwake = False petDogIsPresent = False canFreePrisoner knightIsAwake archerIsAwake prisonerIsAwake petDogIsPresent --> False
stealthAttackDamage function that takes a boolean value indicating if Annalyn was detected. This function returns 7 if she was detected, 12 otherwise.
annalynIsDetected = True stealthAttackDamage annalynIsDetected --> 7