5.
7.
[(1,2,3),(4,5,6),(7,8,9),(10,11,12)].

digitToInt :: String -> Int

getLine :: IO String

readFile :: FilePath -> IO String

lines:: String -> [String]

init :: [a] -> [a]

read :: (Read a) => String -> a

run :: IO (Int, Int, [(Int,Int,Int)])
run = do
  contents <- readFile "text.txt"   -- use '<-' here so that 'contents' is a String
  let [a,b,c] = lines contents      -- split on newlines
  let firstLine  = read (init a)    -- 'init' drops the trailing period
  let secondLine = read (init b)
  let thirdLine  = read (init c)    -- this reads a list of Int-tuples
  return (firstLine, secondLine, thirdLine)

line <- getLine

:type line
line :: String

:type getLine
getLine :: IO String

main = do
    putStrLn "How much do you love Haskell?"
    amount <- getLine
    putStrln ("You love Haskell this much: " ++ amount)

:type readFile
readFile :: FilePath -> IO String

yourdata <- readFile "samplefile.txt"

:type yourdata
text :: String

fmap doTheRightThingWithString readStringFromFile

import Control.Applicative

...

doTheRightThingWithString <$> readStringFromFile

import Control.Monad

...

liftM doTheRightThingWithString readStringFromFile

readStringFromFile >>= string -> return (doTheRightThingWithString string)
readStringFromFile >>= string -> return $ doTheRightThingWithString string
readStringFromFile >>= return . doTheRightThingWithString
return . doTheRightThingWithString =<< readStringFromFile

do
  ...
  string <- readStringFromFile
  -- ^ you escape String from IO but only inside this do-block
  let result = doTheRightThingWithString string
  ...
  return result

myParser :: String -> Foo

readFile "thisfile.txt"

fmap myParser (readFile "thisfile.txt")