Lazy enumerators in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a lazy enumerator from an array.

Ruby

numbers = [1, 2, 3, 4, 5]
lazy_enum = numbers.[1]

Drag options to blanks, or click blank then click option'

Alazy

Bmap

Cselect

Deach

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'map' or 'select' directly without 'lazy' creates immediate enumerables.

Using 'each' returns the original enumerable, not lazy.

The lazy method converts an enumerable into a lazy enumerator, allowing deferred computation.

2fill in blank

medium

Complete the code to get the first 3 even numbers lazily.

Ruby

numbers = (1..Float::INFINITY).lazy
result = numbers.select { |n| n.even? }.[1](3).force

Drag options to blanks, or click blank then click option'

Atake

Bmap

Cdrop

Dfirst

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'first' returns an element immediately, not a lazy enumerator.

Using 'drop' skips elements instead of taking them.

The take method selects the first N elements lazily before forcing evaluation.

3fill in blank

hard

Fix the error in the code to lazily map and select odd numbers.

Ruby

numbers = (1..10).lazy
result = numbers.[1] { |n| n * 2 }.select(&:odd?).force

Drag options to blanks, or click blank then click option'

Aselect

Beach

Cmap

Dreject

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'select' instead of 'map' applies a filter, not a transformation.

Using 'each' does not return a lazy enumerator.

The map method transforms each element lazily before selection.

4fill in blank

hard

Fill both blanks to create a lazy enumerator that drops the first 5 elements and takes the next 3.

Ruby

numbers = (1..100).lazy
result = numbers.[1](5).[2](3).force

Drag options to blanks, or click blank then click option'

Adrop

Btake

Cselect

Dmap

Attempts:

3 left

💡 Hint

Common Mistakes

Reversing the order of 'take' and 'drop' changes the result.

Using 'select' or 'map' instead of 'drop' or 'take' changes behavior.

drop skips the first N elements lazily, and take selects the next N elements lazily.

5fill in blank

hard

Fill all three blanks to create a lazy enumerator that maps numbers to their squares and selects those greater than 10.

Ruby

numbers = (1..10).lazy
result = numbers.[1] { |n| n * n }.[2] { |n| n [3] 10 }.force

Drag options to blanks, or click blank then click option'

Amap

Bselect

C>

Ddrop

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'drop' instead of 'select' changes filtering behavior.

Using '<' instead of '>' changes the filter condition.

map transforms numbers to their squares, select filters those greater than 10.