🎉 Exercism Research is now launched. Help Exercism, help science and have some fun at research.exercism.io 🎉
Sign up Log in

Exercises on the Emacs Lisp track

Join the Emacs Lisp Track
28 exercises to help you master Emacs Lisp
easy

Hello World

The classical introductory exercise. Just say "Hello, World!"
strings
easy

Two Fer

Create a sentence of the form "One for X, one for me."
strings
easy

Leap

Given a year, report if it is a leap year.
control flow conditionals
equality
integers
logic
easy

Anagram

Given a word and a list of possible anagrams, select the correct sublist.
equality
filtering
strings
easy

Roman Numerals

Write a function to convert from normal numbers to Roman Numerals.
control flow conditionals
control flow loops
integers
strings
text formatting
easy

Hamming

Calculate the Hamming difference between two DNA strands.
control flow conditionals
control flow loops
equality
filtering
strings
easy

RNA Transcription

Given a DNA strand, return its RNA Complement Transcription.
control flow conditionals
strings
transforming
easy

Bob

Bob is a lackadaisical teenager. In conversation, his responses are very limited.
control flow conditionals
parsing
strings
easy

Word Count

Given a phrase, count the occurrences of each word in that phrase.
control flow conditionals
control flow loops
filtering
strings
easy

Difference Of Squares

Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.
math
control flow loops
floating point numbers
integers
easy

Gigasecond

Given a moment, determine the moment that would be after a gigasecond has passed.
date
integers
time
transforming
variables
easy

Pangram

Determine if a sentence is a pangram.
strings
control flow loops
easy

Binary

Convert a binary number, represented as a string (e.g. '101010'), to its decimal equivalent using first principles
math
bitwise operations
control flow conditionals
integers
easy

Allergies

Given a person's allergy score, determine whether or not they're allergic to a given item, and their full list of allergies.
bitwise operations
control flow conditionals
integers
text formatting
easy

Robot Name

Manage robot factory settings.
randomness
strings
variables
easy

Atbash Cipher

Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.
control flow conditionals
control flow loops
sequences
transforming
easy

Raindrops

Convert a number to a string, the content of which depends on the number's factors.
control flow conditionals
filtering
integers
easy

Perfect Numbers

Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for natural numbers.
math
number theory
easy

ETL

We are going to do the `Transform` step of an Extract-Transform-Load.
control flow loops
maps
transforming
easy

Nucleotide Count

Given a DNA string, compute how many times each nucleotide occurs in the string.
control flow loops
maps
sorting
strings
easy

Phone Number

Clean up user-entered phone numbers so that they can be sent SMS messages.
interfaces
parsing
strings
easy

Grains

Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.
integers
variables
easy

Acronym

Convert a long phrase to its acronym
strings
transforming
easy

Armstrong Numbers

Determine if a number is an Armstrong number
math
easy

Run Length Encoding

Implement run-length encoding and decoding.
misc
easy

Trinary

Convert a trinary number, represented as a string (e.g. '102012'), to its decimal equivalent using first principles.
math
easy

Crypto Square

Implement the classic method for composing secret messages called a square code.
strings
transforming
cryptograpy
easy

Luhn

Given a number determine whether or not it is valid per the Luhn formula.
strings
checksums
list operations