-- Lecture 3B
-- IO
-- David Sands

-- **** 
-- Small examples of IO
-- putStr, writeFile

-- * Building instructions vs running instructions
-- instructions with results:

-- Readfile

-- putStr putStrLn

-- building complex instructions from simple ones
-- joining instructions, simple form:

verboseWritefile :: FilePath -> String -> IO()
verboseWritefile file contents = do
        putStrLn ("Writing the file " ++ file)
        putStrLn ("The contents are " ++ take 20 contents ++ "...")
        writeFile file contents
        putStrLn "Done!"

-- Joining instructions, using results
-- copyFile


greeting :: IO()
greeting = putStrLn "Hi"

copyFile :: FilePath -> FilePath -> IO()
copyFile fromFile toFile = do
     s <- readFile fromFile
     writeFile toFile s
     
-- return

lengthFile :: FilePath -> IO Int
lengthFile file = do
    s <- readFile file
    return (length s) 


-- doTwice

-- doNot

-- find longest Word in the file "/usr/share/dict/words"
dict :: FilePath
dict = "/usr/share/dict/words"