Ractor for true parallelism in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new Ractor that prints 'Hello from Ractor!'.

Ruby

r = Ractor.new { puts [1] }
r.take

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

AHello from Ractor!

B'Hello from Ractor!'

C"Hello from Ractor!"

Dputs 'Hello from Ractor!'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put quotes around the string.

Putting the entire puts statement inside the block as a string.

The code inside the Ractor block must be a string literal to print. Using single quotes correctly defines the string.

2fill in blank

medium

Complete the code to send a message 'ping' to the Ractor and receive a reply.

Ruby

r = Ractor.new do
  msg = Ractor.receive
  Ractor.yield(msg + [1])
end
r.send('ping')
puts r.take

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

A'pong'

B:pong

Cpong

D"pong"

Attempts:

3 left

💡 Hint

Common Mistakes

Using an unquoted pong which causes an error.

Using a symbol instead of a string.

The Ractor receives a string and appends another string 'pong'. The string must be quoted.

3fill in blank

hard

Fix the error in the code to correctly pass data to the Ractor.

Ruby

r = Ractor.new([1]) do |data|
  data * 2
end
puts r.take

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

A[5]

B5, 10

C"5"

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a bare value instead of an array.

Passing multiple arguments without wrapping.

The Ractor.new method expects a single argument to pass to the block. It must be wrapped in an array to be passed as one argument.

4fill in blank

hard

Fill both blanks to create a Ractor that calculates squares of numbers and returns a hash.

Ruby

numbers = [1, 2, 3]
squares = Ractor.new(numbers) do |nums|
  nums.each_with_object([1]) do |n, h|
    h[n] = n [2] 2
  end
end
puts squares.take

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

A{}

B[]

C**

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using an array instead of a hash for each_with_object.

Using multiplication instead of exponentiation.

The method each_with_object needs a hash as the initial object, so use {}. To calculate squares, use the exponent operator **.

5fill in blank

hard

Fill all three blanks to create a Ractor that filters even numbers and sums them.

Ruby

nums = [1, 2, 3, 4, 5, 6]
r = Ractor.new(nums) do |list|
  evens = list.select { |num| num [1] 2 [2] 0 }
  evens.[3](:+)
end
puts r.take

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

A%

B==

Creduce

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using != instead of == for filtering evens.

Using sum instead of reduce (sum is not available in all Ruby versions).

To filter even numbers, use modulo % 2 == 0. To sum the numbers, use reduce(:+).