Add new LFE exercises
One of the easiest ways to add new exercises to the LFE track is to translate them from other language tracks on Exercism. This page lists all of the problem specifications in the common pool of exercises which have not yet been implemented in LFE.
The icon links to the language-independent description of the problem.
The icon links to the canonical test data.
We also link to all the implementations of each exercise in other languages, which you can use for inspiration.
Once you've picked an exercise, follow the instructions in this guide and submit your pull request to the LFE track repository on GitHub.
The classical introductory exercise. Just say "Hello, World!"
Convert a number to a string, the contents of which depend on the number's factors.
Determine if a triangle is equilateral, isosceles, or scalene.
Write a function to convert from normal numbers to Roman Numerals.
Determine if a sentence is a pangram.
Given a word, compute the scrabble score for that word.
Convert a long phrase to its acronym
Calculate the number of steps to reach 1 using the Collatz conjecture
Determine if a word or phrase is an isogram.
Compute Pascal's triangle up to a given number of rows.
Manage robot factory settings.
Given a number n, determine what the nth prime is.
Use the Sieve of Eratosthenes to find all the primes from 2 up to a given number.
All Your Base
Convert a number, represented as a sequence of digits in one base, to any other base.
Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for natural numbers.
Compute the prime factors of a given natural number.
Implement a binary search algorithm.
Make sure the brackets and braces all match.
Implement the classic method for composing secret messages called a square code.
Implement a program that translates from English to Pig Latin
Run Length Encoding
Implement run-length encoding and decoding.
Given a number from 0 to 999,999,999,999, spell out that number in English.
Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.
Given the position of two queens on a chess board, indicate whether or not they are positioned so that they can attack each other.
Take a nested list and return a single list with all values except nil/null
Add the numbers to a minesweeper board
Create a sentence of the form "One for X, one for me."
Parse and evaluate simple math word problems returning the answer as an integer.
Given a letter, print a diamond starting with 'A' with the supplied letter at the widest point.
Write a function to determine if a list is a sublist of another list.
Binary Search Tree
Insert and search for numbers in a binary tree.
Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.
Create a custom set type.
Implement basic list operations
Detect saddle points in a matrix.
Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is represented, or whether it is garbled.
Correctly determine change to be given using the least number of coins
Check if a given string is a valid ISBN-10 number.
Implement a doubly linked list
Detect palindrome products in a given range.
Translate RNA sequences into proteins.
There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find the product a * b * c.
Take input text and output it transposed.
Generate the lyrics of the song 'I Know an Old Lady Who Swallowed a Fly'
Given a diagram, determine which plants each child in the kindergarten class is responsible for.
Given a string representing a matrix of numbers, return the rows and columns of that matrix.
Implement a simple shift cipher like Caesar and a more secure substitution cipher
Implement a basic reactive system.
Simple Linked List
Write a simple linked list implementation that uses Elements and a List
Output the lyrics to 'The Twelve Days of Christmas'
Write a function to solve alphametics puzzles.
Implement complex numbers.
Implement an evaluator for a very simple subset of Forth
Compute the result for a game of Hex / Polygon
Output the nursery rhyme 'This is the House that Jack Built'.
Given the size, return a square matrix of numbers in spiral order.
Determine if a number is an Armstrong number
Make a chain of dominoes.
Pick the best hand(s) from a list of poker hands.
Rail Fence Cipher
Implement encoding and decoding for the rail fence cipher.
Tally the results of a small football competition.
Variable Length Quantity
Implement variable length quantity encoding and decoding.
To try and encourage more sales of different books from a popular 5 book series, a bookshop has decided to offer discounts of multiple-book purchases.
For want of a horseshoe nail, a kingdom was lost, or so the saying goes. Output the full text of this proverbial rhyme.
Count the rectangles in an ASCII diagram.
Given two buckets of different size, demonstrate how to measure an exact number of liters.
Creating a zipper for a binary tree.
Diffie-Hellman key exchange.
Refactor a Markdown parser
Reparent a graph on a selected node
Generate musical scales, given a starting note and a set of intervals.
Create a program to solve a word search puzzle.
Implement various kinds of error handling and resource management
Search a file for lines matching a regular expression pattern. Return the line number and contents of each matching line.
Count the scored points on a Go board.
Implement rational numbers.
Write a Domain Specific Language similar to the Graphviz dot language
Parsing a Smart Game Format string.
Refactor a tree building algorithm.
Implement the logic of the hangman game using functional reactive programming.
Refactor a ledger printer.
Use lenses to update nested records (specific to languages with immutable data).
Report network IO statistics
Score a single throw of dice in the game Yacht