Programming Task #3: A Role-Playing Adventure
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Programming Task #3: A Role-Playing Adventure
Version 1.0: 11 April 2022
Academic Integrity
As a reminder of the course honor policy, all work submitted for this programming task must be yours alone. Refer to the General Information about Programming Tasks section of Blackboard for more details about what is permitted and not permitted.
Learning Targets
This programming task relates directly to the following Learning Target(s):
● P.3: I can use pattern matching and algebraic datatypes to write data-directed functions/programs.
Before You Start: Read This
Grab a copy of the file RPGdefs .hs, and place it in the same directory where you will write your code. Make sure you save it with this name and capitalization. However, do not add your code to this file: instead, include an import RPGdefs directive at the top of your file.
Background
This assignment involves the components of a very simple role-playing game (RPG):
● There are two sorts of adventurers/heros: mages and warriors .
● There are five sorts of items that heros might carry/hold: amulets , gold coins , potions , shields , and weapons .
Each shield provides an amount of defensive protection, represented by a numeric value. Likewise, each weapon provides an amount of offensive power, represented by a numeric value.
● Each warrior can hold an arbitrary number of items (represented by a list).
In contrast, a mage always holds exactly one item: he may exchange one item for another, but at any instant he has one item in his possession.
● Every mage has a base offensive-power level (represented by an integer).
Some mages (but not all) also have a special ability:
– A mage with the Health ability can survive any attack, regardless of how powerful the attack might be.
– A mage with the Wealth ability can purchase any item with a single coin, regardless of the item’s purchase price.
● Each warrior has a subidentity, representing her preferred fighting style: archer , swordster , or brute . A warrior’s base offensive-power level is given by her fighting style, as shown in the following table:
Fighting Style Base Offense
Archer 2
Swordster 3
Brute 5
● Heroes may purchase items by using their gold. The following table gives the cost (in terms of gold coins) for the various items:
|
Item |
Cost to Buy |
|
Amulet |
1 |
|
Gold |
1 |
|
Potion |
3 |
|
Level-n Shield |
2n |
|
Level-n Weapon |
2n + 1 |
So, for example, a level-4 shield costs a hero eight gold coins to buy. A mage with the Wealth ability can purchase anything for one gold, regardless of the item’s stated cost.
The file RPGdefs .hs contains Haskell datatype definitions to represent these game elements. Take a look at the file, and you’ll notice two important things about these definitions:
1. None of the new types belong to the Eq class.
As a result, you won’t be able to use == or /= to compare elements of these types. Instead, you will need to use Haskell’s pattern-matching facilities.
2. There is no limit to the number of items that a warrior can hold: for example, Warrior Brute [Gold, Amulet, Shield 2, Weapon 1, Gold, Shield 2, Shield 4, Gold] represents a brute who is carrying three gold pieces, one amulet, three separate shields (two at level 2 and one at level 4), and one level-1 weapon. (The order in which the items appear in the list is unimportant.)
Your Problems
For many of the functions, you will need to manipulate lists in various ways: I found list comprehensions
particularly helpful and concise. You could also use recursion (a bit more cumbersome) or map/filter.
1. Define the following Haskell names/variables (they will be useful for testing out subsequent functions):
a. A variable mage1 of type Hero whose value represents a mage with the Health ability, who currently possesses a potion and has a base offensive power level of 5
b. A variable mage2 of type Hero whose value represents a mage with the Wealth ability, who currently possesses gold, and has a base offensive power level of 2
c. A variable mage3 of type Hero whose value represents a mage with the Wealth ability, who currently possesses a level-6 weapon, and has a base offensive power level of 4
d. A variable mage4 of type Hero whose value represents a mage with no special abilities, who currently possesses a level-5 shield, and has a base offensive power level of 7
e. A variable fighter1 of type Hero whose value represents an archer who is currently holding no items
f. A variable fighter2 of type Hero whose value represents a brute who’s currently holding the following: two gold pieces, an amulet, and two weapons (one at level 6 and one at level 2)
g. A variable fighter3 of type Hero whose value represents an archer who is currently holding the following items: three potions, two amulets, a gold piece, and a level-3 shield
h. A variable fighter4 of type Hero whose value represents a swordster who is currently holding the following items: two shields (one at level 4 and one at level 3), a level-2 weapon, a potion, two amulets, and three gold pieces
2. Write a Haskell function
cost :: Item -> Integer
such that cost item returns the cost (in gold) of item.
Examples:
● cost Potion evaluates to 3
● cost (Shield 5) evaluates to 10
● cost (Weapon 5) evaluates to 11
3. Write a Haskell function
hasPotion :: Hero -> Bool
such that hasPotion hero determines whether hero possesses at least one potion.
● hasPotion mage1 evaluates to True
● hasPotion mage2 evaluates to False
● hasPotion fighter2 evaluates to False
● hasPotion fighter3 evaluates to True
4. Write a Haskell function
canBuy :: Hero -> Item -> Bool
such that canBuy hero item determines whether hero has sufficient wealth to purchase item.
Examples:
● canBuy mage2 (Shield 2) evaluates to True
● canBuy mage3 (Shield 2) evaluates to False
● canBuy fighter2 Potion evaluates to False
● canBuy fighter4 Potion evaluates to True
5. Write a Haskell function
boostShields :: Integer -> Hero -> Hero
such that boostShields k hero adds k to the level of each shield that hero possesses.
● boostShields 10 mage1 evaluates to Mage 5 Health Potion
● boostShields 10 mage4 evaluates to Mage 7 None (Shield 15)
● boostShields 10 fighter4 evaluates to Warrior Swordster [Shield 14,Shield 13,Weapon 2,Potion,Amulet,Amulet,Gold,Gold,Gold]
6. A hero’s total offensive power is the sum of her base offensive power and the level of all of her weapons. (Note that shields are not weapons.)
Write a Haskell function
heroPower :: Hero -> Integer
such that heroPower hero calculates the total offensive power for hero.
Examples:
● heroPower mage3 evaluates to 10
● heroPower mage4 evaluates to 7
● heroPower fighter1 evaluates to 2
● heroPower fighter2 evaluates to 13
● heroPower fighter3 evaluates to 2
7. A hero can survive an attack of level n (where n is an integer) provided that their total defensive protection (i.e., the sum of the levels of all of their shields) is n or higher. In addition, a mage with the Health ability will survive attacks of any level.
Write a Haskell function
canSurvive :: Hero -> Integer -> Bool
such that canSurvive hero force determines whether hero could survive an attach of level force.
Examples:
● canSurvive mage1 4 evaluates to True (Health ability)
● canSurvive mage3 4 evaluates to False (total defense is 0)
● canSurvive mage4 4 evaluates to True (total defense is 5)
● canSurvive fighter2 4 evaluates to False (total defense is 0)
● canSurvive fighter4 4 evaluates to True (total defense is 7)
8. Write a Haskell function
bestShield :: Hero -> Integer
such that bestshield hero calculates the strength of the strongest shield in hero’s possession. If hero does not possess a shield, the function returns 0.
Examples:
● bestShield mage1 evaluates to 0
● bestShield mage4 evaluates to 5
● bestShield fighter2 evaluates to 0
● bestShield fighter4 evaluates to 4
What to Submit
You should submit a single Haskell file that meets the following requirements:
● There is a comment with your name and syr .edu email address at the top of the file.
● Functions (and the names/variables from Problem 1) should be given the stated names, have correct type signatures, and appear in the order listed in this task writeup.
● For each of the requested functions, you should provide:
– A brief comment that describes the purpose of the function (this can be taken from the task description itself)
– The function definition, including the type signature
– Specific test cases that can be used to verify the correctness of your function (these tests should be designed before and as you write your code, not as an afterthought)
How it Will be Graded
Programming tasks are graded using the MRUN rubric found in the syllabus:
● The code meets the submission requirements listed above. To earn an M, you must have working solutions for at least 6 of the functions.
– The code meets the submission requirements listed above. To earn an R, you must have working solutions for at least half of the functions.
● Your code is reasonably concise and works correctly on test data that we prepare separately. Use wise pattern matching to reduce the number of equations required for your functions .
2022-11-10