MiyamonY

import System.Random

main :: IO ()
main = do
  gen <- getStdGen
  putStrLn $ take 20 $ randomRs ('a', 'z') gen
  gen' <- newStdGen
  putStrLn $ take 20 $ randomRs ('a', 'z') gen'

MiyamonY

import System.Random
import Control.Monad (when)

main :: IO ()
main = do
  gen <- getStdGen
  askForNumber gen


askForNumber :: StdGen -> IO ()

MiyamonY

import System.Random
import Control.Monad (when)

main :: IO ()
main = do
  gen <- getStdGen
  askForNumber gen


askForNumber :: StdGen -> IO ()

MiyamonY

import System.Environment
import System.Directory
import System.IO
import Control.Exception
import qualified Data.ByteString.Lazy as B

main :: IO ()
main = do
  (fileName : fileName2: _) <- getArgs
  copy fileName fileName2

MiyamonY

solveRPN :: String -> Double
solveRPN = head . foldl foldingFunction [] . words
  where foldingFunction (x:y:ys) "*" = (y * x) : ys
        foldingFunction (x:y:ys) "+" = (y + x) : ys
        foldingFunction (x:y:ys) "-" = (y - x) : ys
        foldingFunction (x:y:ys) "/" = (y / x) : ys
        foldingFunction (x:y:ys) "^" = (y ** x) : ys
        foldingFunction (x:xs) "ln" = log x : xs
        foldingFunction xs "sum" = [sum xs]
        foldingFunction xs numberString = read numberString : xs

MiyamonY

import Data.List

data Section = Section {getA :: Int, getB :: Int, getC :: Int }
               deriving (Show)

type RoadSystem = [Section]

heathrowToLondon :: RoadSystem
heathrowToLondon = [Section 50 10 30,
                    Section 5 90 20,

MiyamonY

import Data.List

data Section = Section {getA :: Int, getB :: Int, getC :: Int }
               deriving (Show)

type RoadSystem = [Section]

heathrowToLondon :: RoadSystem
heathrowToLondon = [Section 50 10 30,
                    Section 5 90 20,

MiyamonY

-- instance Functor IO where
--   fmap f action = do
--     result <- action
--     return (f result)

main :: IO ()
-- main = do line <- getLine
--           let line' = reverse line
--           putStrLn $ "You said " ++ line' ++ " backwards!"
--           putStrLn $ "Yes, you said " ++ line' ++ " backwards"

MiyamonY

import Data.Char
import Data.List

main :: IO ()
main = do line <- fmap (intersperse '-' . reverse . map toUpper) getLine
          putStrLn line

MiyamonY

-- instance Functor ((->) r) where
--   fmap f g = (\ x -> f (g x))

-- instance Functor ((->) r) where
--   fmap = (.)

-- functor laws

-- first law
-- isntance Fucntor Maybe where