mirror of
https://github.com/iritmaximus/haskell.git
synced 2026-10-12 19:13:39 +03:00
146 lines
4.1 KiB
Haskell
146 lines
4.1 KiB
Haskell
module Set11a where
|
|
|
|
import Control.Monad
|
|
import Data.List
|
|
import System.IO
|
|
|
|
import Mooc.Todo
|
|
|
|
-- Lecture 11:
|
|
-- * The IO type
|
|
-- * do-notation
|
|
--
|
|
-- Useful functions / operations:
|
|
-- * putStrLn
|
|
-- * getLine
|
|
-- * readLn
|
|
-- * replicateM
|
|
-- * readFile
|
|
-- * lines
|
|
--
|
|
-- Do not add any new imports! E.g. Data.IORef is forbidden.
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 1: define an IO operation hello that prints two lines. The
|
|
-- first line should be HELLO and the second one WORLD
|
|
|
|
hello :: IO ()
|
|
hello = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 2: define the IO operation greet that takes a name as an
|
|
-- argument and prints a line "HELLO name".
|
|
|
|
greet :: String -> IO ()
|
|
greet name = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 3: define the IO operation greet2 that reads a name from the
|
|
-- keyboard and then greets that name like the in the previous
|
|
-- exercise.
|
|
--
|
|
-- Try to use the greet operation in your solution.
|
|
|
|
greet2 :: IO ()
|
|
greet2 = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 4: define the IO operation readWords n which reads n lines from
|
|
-- the user and produces them as a list, in alphabetical order.
|
|
--
|
|
-- Example in GHCi:
|
|
-- Set11> readWords 3
|
|
-- bob
|
|
-- alice
|
|
-- carl
|
|
-- ["alice","bob","carl"]
|
|
|
|
readWords :: Int -> IO [String]
|
|
readWords n = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 5: define the IO operation readUntil f, which reads lines from
|
|
-- the user and returns them as a list. Reading is stopped when f
|
|
-- returns True for a line. (The value for which f returns True is not
|
|
-- returned.)
|
|
--
|
|
-- Example in GHCi:
|
|
-- *Set11> readUntil (=="STOP")
|
|
-- bananas
|
|
-- garlic
|
|
-- pakchoi
|
|
-- STOP
|
|
-- ["bananas","garlic","pakchoi"]
|
|
|
|
readUntil :: (String -> Bool) -> IO [String]
|
|
readUntil f = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 6: given n, print the numbers from n to 0, one per line
|
|
|
|
countdownPrint :: Int -> IO ()
|
|
countdownPrint n = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 7: isums n should read n numbers from the user (one per line) and
|
|
-- 1) after each number, print the running sum up to that number
|
|
-- 2) finally, produce the sum of all numbers
|
|
--
|
|
-- Example:
|
|
-- 1. run `isums 3`
|
|
-- 2. user enters '3', should print '3'
|
|
-- 3. user enters '5', should print '8' (3+5)
|
|
-- 4. user enters '1', should print '9' (3+5+1)
|
|
-- 5. produces 9
|
|
|
|
isums :: Int -> IO Int
|
|
isums n = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 8: when is a useful function, but its first argument has type
|
|
-- Bool. Write a function that behaves similarly but the first
|
|
-- argument has type IO Bool.
|
|
|
|
whenM :: IO Bool -> IO () -> IO ()
|
|
whenM cond op = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 9: implement the while loop. while condition operation should
|
|
-- run operation as long as condition returns True.
|
|
--
|
|
-- Examples:
|
|
-- -- prints nothing
|
|
-- while (return False) (putStrLn "IMPOSSIBLE")
|
|
--
|
|
-- -- prints YAY! as long as the user keeps answering Y
|
|
-- while ask (putStrLn "YAY!")
|
|
|
|
-- used in an example
|
|
ask :: IO Bool
|
|
ask = do putStrLn "Y/N?"
|
|
line <- getLine
|
|
return $ line == "Y"
|
|
|
|
while :: IO Bool -> IO () -> IO ()
|
|
while cond op = todo
|
|
|
|
------------------------------------------------------------------------------
|
|
-- Ex 10: given a string and an IO operation, print the string, run
|
|
-- the IO operation, print the string again, and finally return what
|
|
-- the operation returned.
|
|
--
|
|
-- Note! the operation should be run only once
|
|
--
|
|
-- Examples:
|
|
-- debug "CIAO" (return 3)
|
|
-- - prints two lines that contain CIAO
|
|
-- - returns the value 3
|
|
-- debug "BOOM" getLine
|
|
-- 1. prints "BOOM"
|
|
-- 2. reads a line from the user
|
|
-- 3. prints "BOOM"
|
|
-- 4. returns the line read from the user
|
|
|
|
debug :: String -> IO a -> IO a
|
|
debug s op = todo
|