Bandwagoner

10 Points

records

Instructions

In this exercise you're a big sports fan and you've just discovered a passion for NBA basketball. Being new to NBA basketball, you're doing a deep dive into NBA history, keeping track of teams, coaches, their win/loss stats and comparing them against each other.

As you don't yet have a favorite team, you'll also be developing an algorithm to figure out whether to root for a particular team. You have seven tasks to help you develop your proprietary root-for-a-team algorithm.

1. Define the model

Define the Coach type alias for a record with the following two fields, in the following order:

name: the coach's name, of type String.
formerPlayer: indicates if the coach was a former player, of type Bool.

Define the Stats type alias for a record with the following two fields, in the following order:

wins: the number of wins, of type Int.
losses: the number of losses, of type Int.

Define the Team type alias for a record with the following three fields, in the following order:

name: the team's name, of type String.
coach: the team's coach, of type Coach.
stats: the team's stats, of type Stats.

2. Create a team

You want to interface with some third party code that has the concept of a team, but which calls your code with the parameters in a different order. Add a createTeam function with the following signature String -> Stats -> Coach -> Team.

3. Replace the coach

NBA owners being impatient, you found that bad team results would often lead to the coach being replaced. Implement the replaceCoach function that takes the new coach and the team as parameters, and returns the team but with the new coach:

let
    coach = { name = "Larry Bird", formerPlayer = True }
    stats = { wins = 58, losses =  24 }
    team = { name = "Indiana Pacers", coach = coach, stats =  stats }
    newCoach = { name = "Isiah Thomas", formerPlayer = True }
in
replaceCoach newCoach team
--> { name = "Indiana Pacers"
--  , coach = { name = "Isiah Thomas", formerPlayer = True }
--  , stats = { wins = 58, losses = 24 } }

4. Check if you should root for a team

In the future, you plan to come up with a complicated algorithm about whether to root for a team or not, but for the first attempt, you have decided that you should root for any team has more wins than losses.

You want this function to be reusable in other contexts, so use an extensible record in the type signature to accept any record that has the relevant fields. To keep the function as concise as possible, you want to use pattern matching to get the stats from the function parameter. Implement the rootForTeam function that takes a team and returns True if you should root for that team; otherwise, return False.

let
    spursCoach = { name = "Gregg Popovich", formerPlayer =  False }
    spursStats = { wins = 56, losses = 26 }
    spursTeam = { name = "San Antonio Spurs", coach = spursCoach, stats = spursStats }
in
rootForTeam spursTeam
--> True

elm