Test.hs

module Main where

import Control.Monad
import Data.List
import Data.Char
import System.IO
import Text.Regex.Posix
import Text.Regex

getSecondWord :: String -> String
getSecondWord = head . tail . words

getLastWord :: String -> String
getLastWord = last . words

myReverse :: [b] -> [b]
myReverse = foldl (flip (:)) []

lastButOne :: [a] -> a
lastButOne = head . reverse . init

data Meow a = Meow a 
              deriving (Show)

splitDigits :: String -> [Int]
splitDigits = map digitToInt

addNum :: Int -> Int
addNum = foldl' (+) 0 . splitDigits . show

myLast :: [a] -> a
myLast = head . reverse


data Tree a = Node a (Tree a) (Tree a)
            | Empty
              deriving (Show)

countLetters :: String -> Int
countLetters xs = 
    length $ filter (/= ' ') $ subRegex (mkRegex "[^aA-zZ]") xs ""

data List a = Cons a (List a)
            | Nil
              deriving (Show)

fromList :: [a] -> List a
fromList (x:xs) = Cons x $ fromList xs
fromList []     = Nil

toList :: List a -> [a]
toList (Cons x xs) = x : (toList xs)
toList Nil         = []

data Treetwo a = Nodetwo a (Maybe (Treetwo a)) (Maybe (Treetwo a))
                 deriving (Show)