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fp:lab04 [2022/03/09 20:33] pdmatei |
fp:lab04 [2022/05/15 23:54] (current) vbadoiu old revision restored (2022/03/25 10:15) |
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| ===== 4. Lists in Scala ===== | ===== 4. Lists in Scala ===== | ||
| + | |||
| + | Objectives: | ||
| + | * get familiar with **pattern matching** lists, as well as common list operations from Scala and how they work | ||
| + | * get familiar with common **higher-order functions** over lists (partition, map, foldRight, foldLeft, filter) | ||
| ==== 4.1. Common list operations ==== | ==== 4.1. Common list operations ==== | ||
| Line 14: | Line 18: | ||
| <code scala> | <code scala> | ||
| def take(n: Int, l: List[Int]): List[Int] = ??? | def take(n: Int, l: List[Int]): List[Int] = ??? | ||
| - | //take(3,List(1,2,3,4,5)) = 3 | + | //take(3,List(1,2,3,4,5)) = List(1,2,3) |
| </code> | </code> | ||
| Line 56: | Line 60: | ||
| **4.2.1.** Write a function which adds one point to all students which have a passing grade (>= 5), and leaves all other grades unchanged. | **4.2.1.** Write a function which adds one point to all students which have a passing grade (>= 5), and leaves all other grades unchanged. | ||
| + | <code scala> | ||
| + | def increment(g: Gradebook): Gradebook = | ||
| + | g.map(???) | ||
| + | </code> | ||
| + | **4.2.2.** Find the average grade from a gradebook. You must use ''foldRight''. | ||
| + | <code scala> | ||
| + | def average(g: Gradebook): Double = ??? | ||
| + | </code> | ||
| + | **4.2.3.** Write a function which takes a gradebook and returns the percentage of failed vs. passed students, as a pair (x,y). | ||
| + | <code scala> | ||
| + | def percentage(g: Gradebook): (Double,Double) = ??? | ||
| + | </code> | ||
| + | |||
| + | **4.2.4.** Write a function which takes a gradebook and returns the list of names which have passed. Use filter and map from Scala. | ||
| + | <code scala> | ||
| + | def pass(g: Gradebook): List[String] = ??? | ||
| + | </code> | ||
| + | |||
| + | **4.2.5.** Implement merge-sort (in ascending order) over gradebooks: | ||
| + | <code scala> | ||
| + | def mergeSort(l: Gradebook): Gradebook = { | ||
| + | def merge(u: Gradebook, v: Gradebook): Gradebook = ??? | ||
| + | ??? | ||
| + | } | ||
| + | </code> | ||
| + | |||
| + | **4.2.6** Write a function which takes a gradebook and reports all passing students in **descending** order of their grade. | ||
| + | <code scala> | ||
| + | def honorsList(g: Gradebook): List[String] = ??? | ||
| + | </code> | ||