Lambda creation and behavior in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a lambda in Ruby?

A lambda is a special kind of anonymous function or block that can be stored in a variable and called later. It behaves like a method and can take arguments and return values.

beginner

How do you create a lambda in Ruby?

You can create a lambda using either lambda { |args| ... } or ->(args) { ... } syntax.

intermediate

What happens if you use return inside a lambda?

Using return inside a lambda exits only from the lambda itself, not from the surrounding method or block.

intermediate

How does a lambda differ from a Proc in Ruby?

A lambda checks the number of arguments passed and treats return differently (returns from lambda only). A Proc does not check arguments strictly and return exits from the enclosing method.

beginner

How do you call a lambda stored in a variable?

You call a lambda by using the .call method on the variable, like my_lambda.call(args).

Which syntax creates a lambda in Ruby?

A proc { |x| x * 2 }

B ->(x) { x * 2 }

C def lambda(x); x * 2; end

D function(x) { return x * 2 }

The arrow syntax ->(x) { ... } creates a lambda in Ruby.

What happens if you pass the wrong number of arguments to a lambda?

A It raises an ArgumentError.

B It ignores extra arguments.

C It sets missing arguments to nil.

D It runs without error.

Lambdas check argument count strictly and raise ArgumentError if it doesn't match.

What does return inside a lambda do?

A Raises an error.

B Returns from the enclosing method.

C Returns from the lambda only.

D Exits the program.

Return inside a lambda exits only the lambda, not the surrounding method.

How do you execute a lambda stored in variable f?

A f.execute()

B f.run()

C call f()

D f.call()

You call a lambda using the .call method.

Which is true about lambdas compared to Procs?

A Lambdas check arguments and Procs do not.

B Procs check arguments and Lambdas do not.

C Both behave exactly the same.

D Lambdas cannot be stored in variables.

Lambdas check argument count strictly, Procs do not.

Explain how to create and call a lambda in Ruby, including the syntax options.

Think about the arrow syntax and the lambda keyword.

Describe the difference in behavior between a lambda and a Proc when using return and argument checking.

Focus on how return and arguments behave differently.