Scala Scala Collections 3

Question 1

What does `scanLeft` do in Scala compared to `foldLeft`?

Accepted Answer

scanLeft returns all intermediate accumulator values, not just the final result

Answer

`scanLeft` produces a collection of all intermediate accumulator values including the initial value, while `foldLeft` returns only the final value.

Question 2

What is a `SortedMap` in Scala?

Accepted Answer

A Map that iterates keys in sorted order

Answer

`SortedMap` maintains keys in sorted order (using an implicit `Ordering`), iterating entries from smallest to largest key.

Question 3

How do you safely access a Map value in Scala without risking an exception?

Accepted Answer

map.get(key) returns Option

Answer

`map.get(key)` returns `Some(value)` if the key exists or `None` if it doesn't, avoiding `NoSuchElementException`.

Question 4

What does `zip` produce when applied to collections of different lengths?

Accepted Answer

A collection as long as the shorter one, dropping excess elements

Answer

`zip` truncates to the shorter collection's length, producing only pairs where both collections have elements.

Question 5

What is the difference between `map` and `foreach` on a Scala collection?

Accepted Answer

map returns a new transformed collection; foreach returns Unit and is used for side effects

Answer

`map` transforms elements and returns a new collection, while `foreach` iterates for side effects and returns `Unit`.

Scala Practice Test