Lisp Flavoured Erlang (LFE) Lisp Flavoured Erlang (LFE)

When you're logged in, you can say exercism fetch lfe to get the next available exercise on the track.

Every time you submit a solution to an exercise, you will get the next in line the next time you fetch.

If you want to try a specific exercise, you can always fetch it directly (commands are listed below).

The exercises are ordered roughly in order of difficulty.

Available Exercises

  • Leap Given a year, report if it is a leap year.
  • Rna Transcription Given a DNA strand, return its RNA complement (per RNA transcription).
  • Bob Bob is a lackadaisical teenager. In conversation, his responses are very limited.
  • Sum Of Multiples Given a number, find the sum of all the multiples of particular numbers up to but not including that number.
  • Strain Implement the `keep` and `discard` operation on collections. Given a collection and a predicate on the collection's elements, `keep` returns a new collection containing those elements where the predicate is true, while `discard` returns a new collection containing those elements where the predicate is false.
  • Hamming Calculate the Hamming difference between two DNA strands.
  • Space Age Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.
  • Grains Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.
  • Anagram Given a word and a list of possible anagrams, select the correct sublist.
  • Nucleotide Count Given a DNA string, compute how many times each nucleotide occurs in the string.
  • Atbash Cipher Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.
  • Phone Number Clean up user-entered phone numbers so that they can be sent SMS messages.
  • Robot Simulator Write a robot simulator.
  • Grade School Given students' names along with the grade that they are in, create a roster for the school
  • Binary Convert a binary number, represented as a string (e.g. '101010'), to its decimal equivalent using first principles
  • Word Count Given a phrase, count the occurrences of each word in that phrase.
  • Circular Buffer A data structure that uses a single, fixed-size buffer as if it were connected end-to-end.
  • Etl We are going to do the `Transform` step of an Extract-Transform-Load.
  • Clock Implement a clock that handles times without dates.
  • Gigasecond Calculate the moment when someone has lived for 10^9 seconds.
  • Beer Song Produce the lyrics to that beloved classic, that field-trip favorite: 99 Bottles of Beer on the Wall.
  • Difference Of Squares Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.
  • Allergies Given a person's allergy score, determine whether or not they're allergic to a given item, and their full list of allergies.
  • Bank Account Simulate a bank account supporting opening/closing, withdraws, and deposits of money. Watch out for concurrent transactions!
  • Luhn Given a number determine whether or not it is valid per the Luhn formula.
  • Series Given a string of digits, output all the contiguous substrings of length `n` in that string.
  • Trinary Convert a trinary number, represented as a string (e.g. '102012'), to its decimal equivalent using first principles.
  • Largest Series Product Given a string of digits, calculate the largest product for a contiguous substring of digits of length n.
  • Meetup Calculate the date of meetups.
  • Parallel Letter Frequency Count the frequency of letters in texts using parallel computation.