Pipeline operator concept in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to use the pipeline operator to convert a string to uppercase.

Ruby

result = "hello" [1] String.upcase

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

A->

B::

C|>

D=>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '->' which is for lambdas, not pipelines.

Using '::' which is for constants or modules.

Using '=>' which is for hashes.

The pipeline operator |> passes the value on the left as an argument to the method on the right.

2fill in blank

medium

Complete the code to chain two methods using the pipeline operator.

Ruby

result = "  ruby  " [1] String.strip [2] String.upcase

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

A->

B|>

C::

D=>

Attempts:

3 left

💡 Hint

Common Mistakes

Using different operators for chaining.

Forgetting to repeat the operator between methods.

The pipeline operator |> allows chaining methods by passing the result of one method to the next.

3fill in blank

hard

Fix the error in the pipeline usage to correctly reverse and then capitalize a string.

Ruby

result = "hello" [1] String.reverse [2] String.capitalize

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

A|>

B||

C&&

D->

Attempts:

3 left

💡 Hint

Common Mistakes

Using logical operators like '||' or '&&' which do not chain methods.

Using '->' which is for lambdas.

The pipeline operator |> correctly passes the output of one method as input to the next.

4fill in blank

hard

Fill both blanks to create a pipeline that doubles a number and then converts it to a string.

Ruby

result = 5 [1] 2.method(:*) [2] String

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

A|>

B*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using arithmetic operators instead of pipeline operators between methods.

Mixing different operators for chaining.

The pipeline operator |> is used twice to chain the multiplication and string conversion.

5fill in blank

hard

Fill all three blanks to create a pipeline that trims spaces, reverses, and then converts to uppercase.

Ruby

result = "  ruby " [1] String.strip [2] String.reverse [3] String.upcase

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

A|>

D->

Attempts:

3 left

💡 Hint

Common Mistakes

Using different operators in the chain.

Using lambda arrow '->' instead of pipeline operator.

Use the pipeline operator |> for all three steps to chain the methods properly.

Practice

1.

What does the Ruby pipeline operator |> do?

easy

A. It creates a new array from two arrays.

B. It combines two strings into one.

C. It passes the value on the left as the first argument to the method on the right.

D. It comments out the code on the right.

Solution

1. Step 1: Understand the operator's purpose

   The pipeline operator |> takes the value on its left side and sends it as the first argument to the method on its right side.

2. Step 2: Compare with other options

   Options B, C, and D describe unrelated operations like string concatenation, array merging, or commenting, which are not what |> does.

3. Final Answer:

   It passes the value on the left as the first argument to the method on the right. -> Option C

4. Quick Check:

   Pipeline operator = Pass left value as first argument [OK]

Hint: Remember: left value flows into right method as first argument [OK]

Common Mistakes:

• Thinking it concatenates strings
• Confusing it with array merging
• Assuming it comments code

2.

Which of the following is the correct syntax to use the pipeline operator in Ruby?

value ___ method_name

easy

A. |>

B. |

C. ->

D. |>

Solution

1. Step 1: Identify the correct operator symbol

   The Ruby pipeline operator is written as |> without any extra characters or spaces.

2. Step 2: Check each option

   -> uses an arrow -> which is for lambdas, not pipelines. | is just a pipe character, not the pipeline operator. |> has an extra closing tag which is invalid syntax.

3. Final Answer:

   |> -> Option A

4. Quick Check:

   Correct pipeline syntax = |> [OK]

Hint: Look for the exact two-character operator: pipe then greater than [OK]

Common Mistakes:

• Using -> instead of |> operator
• Adding extra characters like
• Missing the greater than symbol

3.

What is the output of the following Ruby code?

def double(x)
  x * 2
end

result = 5 |> double
puts result

medium

A. 25

B. 5double

C. SyntaxError

D. 10

Solution

1. Step 1: Understand the pipeline operation

   The value 5 is passed as the first argument to the method double, so it calls double(5).

2. Step 2: Calculate the method result

   double(5) returns 5 * 2 = 10, so result is 10, which is printed.

3. Final Answer:

   10 -> Option D

4. Quick Check:

   5 |> double = 10 [OK]

Hint: Pipeline passes 5 to double, so output doubles 5 [OK]

Common Mistakes:

• Thinking it concatenates '5' and 'double'
• Expecting a syntax error
• Multiplying 5 by itself instead of 2

4.

Identify the error in this Ruby code using the pipeline operator:

def greet(name)
  "Hello, #{name}!"
end

message = "Alice" |>
  greet
puts message

medium

A. The pipeline operator is missing the right side method.

B. The pipeline operator is split incorrectly across lines.

C. The pipeline operator should be -> instead of |>.

D. The method greet should not use string interpolation.

Solution

1. Step 1: Check pipeline operator usage across lines

   The pipeline operator |> must be on the same line as the left value or properly continued. Here, it is split with a newline after |>, which causes a syntax error.

2. Step 2: Verify other options

   The pipeline operator is missing the right side method. is wrong because the right side method greet is present. The pipeline operator should be -> instead of |>. confuses the operator with lambda syntax. The method greet should not use string interpolation. is unrelated to the pipeline error.

3. Final Answer:

   The pipeline operator is split incorrectly across lines. -> Option B

4. Quick Check:

   Pipeline operator must not be broken by newline [OK]

Hint: Keep pipeline operator and method call on same line [OK]

Common Mistakes:

• Splitting pipeline operator and method on different lines
• Confusing pipeline with lambda syntax
• Blaming string interpolation for error

5.

Given the following methods, what is the output of this Ruby code using the pipeline operator?

def add_one(x)
  x + 1
end

def square(x)
  x * x
end

result = 3 |> add_one |> square
puts result

hard

A. 16

B. 10

C. 7

D. 9

Solution

1. Step 1: Apply the first pipeline operation

   The value 3 is passed to add_one, so add_one(3) returns 4.

2. Step 2: Apply the second pipeline operation

   The result 4 is then passed to square, so square(4) returns 16.

3. Final Answer:

   16 -> Option A

4. Quick Check:

   3 |> add_one |> square = 16 [OK]

Hint: Pipeline chains: left to right, each result feeds next method [OK]

Common Mistakes:

• Calculating square before add_one
• Adding 1 after squaring
• Confusing order of operations