A Collection of Code Snippets in as Many Programming Languages as Possible

This project is maintained by TheRenegadeCoder

Welcome to the Longest Common Subsequence in Haskell page! Here, you'll find the source code for this program as well as a description of how the program works.

```
module Main where
import System.Environment
import System.Exit (exitWith, ExitCode(ExitFailure))
import Data.List (intercalate)
-- Recursively find longest common subsequence
lcs :: Eq a => [a] -> [a] -> [a]
lcs [] bs = []
lcs as [] = []
lcs (a:as) (b:bs)
| a == b = (lcs as bs) ++ [a]
| otherwise = longest (lcs (a:as) bs) (lcs as (b:bs))
-- Returns the longer of two lists
longest :: Foldable t => t a -> t a -> t a
longest l1 l2
| length l1 > length l2 = l1
| otherwise = l2
-- Converts string in format "1, 2, 3" to a list of integers
stringToList :: String -> [Int]
stringToList str = read $ "[" ++ str ++ "]" :: [Int]
listToString :: [Int] -> String
listToString = intercalate ", " . map show
main :: IO ()
main = do
args <- getArgs
let l1 = stringToList $ head args :: [Int]
let l2 = stringToList $ head $ tail args :: [Int]
if length args /= 2 then do
putStrLn "Usage: please provide two lists in the format \"1, 2, 3, 4, 5\""
exitWith $ ExitFailure 1
else
putStrLn $ listToString $ reverse $ lcs l1 l2
```

Longest Common Subsequence in Haskell was written by:

- Parker Johansen

If you see anything you'd like to change or update, please consider contributing.

No 'How to Implement the Solution' section available. Please consider contributing.

No 'How to Run the Solution' section available. Please consider contributing.