Haskell input - how to read x number of inputs from stdin

Question

The user will enter a number of cases, the length of the case, and then the case. The number of cases varies each time. Example of user input:

2
4
"four"
3
"the"

I need to do something to each of the cases, but how do I get the execute the do loop to match the number of cases?

This is what I have so far:

main = do
    numOfCases <- getInteger
    caseLength <- getInteger
    case <- getLine
    putStrLn $ doSomething case
    --how do I call the loop exactly once more, but this time without the numOfCases?

Thanks.

Answer 1

Use replicateM_ , which repeats an action a given number of times. You import it from Control.Monad :

replicateM_ :: (Monad m) => Int -> m a -> m ()

So you would use it like this:

import Control.Monad (replicateM_)

main = do
    numOfCases <- readLn
    replicateM_ numOfCases $ do
        caseLength <- readLn
        str <- getLine
        ... -- do other stuff