Pure functions concept in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a pure function that returns the square of a number.

Ruby

def square(num)
  return num [1] num
end

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 the number to itself, not square it.

Using '/' or '-' will not produce the square.

The function multiplies the input by itself to return the square. This is a pure function because it always returns the same output for the same input without side effects.

2fill in blank

medium

Complete the code to define a pure function that returns the length of a string.

Ruby

def length_of_string(str)
  return str.[1]
end

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Alength

Bsize

Ccount

Dchars

Attempts:

3 left

💡 Hint

Common Mistakes

Using chars returns an array of characters, not the length.

Using count requires an argument and is not the best choice here.

The method length returns the number of characters in the string. This function is pure because it depends only on the input string and has no side effects.

3fill in blank

hard

Fix the error in the pure function that returns the sum of two numbers.

Ruby

def add_numbers(a, b)
  return a [1] b
end

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A/

B-

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' subtracts instead of adds.

Using '*' or '/' changes the operation entirely.

The function should add the two inputs using the '+' operator. This keeps the function pure by returning the sum without side effects.

4fill in blank

hard

Complete the code to create a pure function that returns a hash with word lengths for words longer than 3 characters.

Ruby

def word_lengths(words)
  lengths = {word=> word.length for word in words if word.length [1] 3}
  return lengths
end

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

A=>

B<=

C>

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' or '==' in the condition will select wrong words.

Using ':' instead of '=>' in the hash mapping is incorrect syntax.

The hash uses the '=>' symbol to map words to their lengths. The condition filters words longer than 3 characters using the '>' operator. This function is pure because it depends only on input and returns a new hash without side effects.

5fill in blank

hard

Fill all three blanks to create a pure function that returns a hash of uppercase words and their lengths for words longer than 4 characters.

Ruby

def uppercase_word_lengths(words)
  result = { [1] => [2] for word in words if word.length [3] 4 }
  return result
end

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Aword.upcase

Bword.length

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using word instead of word.upcase will not uppercase the words.

Using '<' or '<=' instead of '>' will select wrong words.

The function maps uppercase words (word.upcase) to their lengths (word.length) for words longer than 4 characters (using >). This is a pure function because it returns the same output for the same input without side effects.