Proc composition in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Proc that doubles a number.

Ruby

double = Proc.new { |x| x [1] 2 }

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of * will add 2 instead of doubling.

Using - or / will not double the number.

The * operator multiplies the number by 2, doubling it.

2fill in blank

medium

Complete the code to compose two Procs: one that doubles, then one that adds 3.

Ruby

double = Proc.new { |x| x * 2 }
add_three = Proc.new { |x| x [1] 3 }
composed = Proc.new { |x| add_three.call(double.call(x)) }

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

A+

B*

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using * will multiply instead of adding.

Using - or / will subtract or divide instead of adding.

The + operator adds 3 to the doubled number.

3fill in blank

hard

Fix the error in the Proc composition to correctly chain two Procs.

Ruby

square = Proc.new { |x| x * x }
double = Proc.new { |x| x * 2 }
composed = Proc.new { |x| [1].call([2].call(x)) }

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

Asquare

Bcomposed

Cdouble

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the same Proc twice causes errors.

Using the wrong Proc name in the call.

To double then square, call square.call(double.call(x)). The outer blank should be square (A) and the inner blank double (C).

4fill in blank

hard

Fill both blanks to create a Proc that adds 1 then multiplies by 5.

Ruby

add_one = Proc.new { |x| x [1] 1 }
multiply_five = Proc.new { |x| x [2] 5 }
composed = Proc.new { |x| multiply_five.call(add_one.call(x)) }

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction instead of addition.

Using division instead of multiplication.

The first Proc adds 1 using +, the second multiplies by 5 using *.

5fill in blank

hard

Fill all three blanks to create a Proc that squares, subtracts 4, then divides by 2.

Ruby

square = Proc.new { |x| x [1] x }
subtract_four = Proc.new { |x| x [2] 4 }
divide_two = Proc.new { |x| x [3] 2 }
composed = Proc.new { |x| divide_two.call(subtract_four.call(square.call(x))) }

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

A*

B-

C/

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up operators like using + instead of -.

Using multiplication instead of division at the end.

The first Proc squares the number using *, the second subtracts 4 using -, and the third divides by 2 using /.