Curry and partial application in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is currying in Ruby?

Currying is a technique where a method with multiple arguments is transformed into a series of methods each taking one argument. It allows you to call a method step-by-step with one argument at a time.

beginner

What does partial application mean?

Partial application means fixing some arguments of a function and creating a new function that takes the remaining arguments. It helps reuse functions with some preset values.

intermediate

How do you create a curried function in Ruby?

You can create a curried function by calling curry on a Proc or lambda. For example: add = ->(a, b) { a + b }.curry creates a curried version of the add function.

intermediate

What is the difference between currying and partial application?

Currying transforms a function to take one argument at a time, returning new functions until all arguments are given. Partial application fixes some arguments and returns a function for the rest. Partial application is a special case of currying.

beginner

Example: How to partially apply a function in Ruby using currying?

Given multiply = ->(a, b) { a * b }.curry, you can fix the first argument like double = multiply.call(2). Now double.call(5) returns 10.

What does the curry method do in Ruby?

A Deletes a function

B Transforms a multi-argument function into a chain of single-argument functions

C Converts a function to a string

D Runs a function multiple times

The curry method changes a function so it takes one argument at a time, returning new functions until all arguments are provided.

What is partial application useful for?

A Making a function run faster

B Deleting arguments from a function

C Changing the function's name

D Fixing some arguments of a function to reuse it easily

Partial application lets you fix some arguments, creating a new function that needs fewer arguments.

Which Ruby object can be curried?

A Proc or lambda

B Integer

C String

D Array

Only Proc or lambda objects can be curried using the curry method.

What will add = ->(a, b) { a + b }.curry; add.call(2).call(3) return?

A nil

B 23

C 5

D Error

Currying allows calling the function one argument at a time. Here, 2 + 3 equals 5.

Partial application is a special case of which concept?

A Currying

B Recursion

C Inheritance

D Polymorphism

Partial application fixes some arguments, and currying transforms functions to take one argument at a time. Partial application is considered a special case of currying.

Explain in your own words what currying is and how it works in Ruby.

Think about how a function with many arguments can be called step-by-step.

Describe partial application and how it differs from currying with an example in Ruby.

Focus on fixing some arguments vs. taking one argument at a time.