CODEWITHSUNDEEP
haskellfunctional-programming
user5951413
user5951413

Reputation:

Reading 2-line input Haskell

I've finished writing a Haskell program but I have troubles with the I/O and Main parts of it. I want to read input of the following format:

10 3
1 4 8

The first and second numbers are Ints, and the numbers of the second line should be made into an integer list, [Int]. The length of the list is equal to the second number on the first line.

I have the following code to read one Int at a time, however, it can only get it to work for the first line of input. 

getInt :: IO Int
getInt = do
    l <- getLine
    return (read l)

What am I doing wrong?

Upvotes: 0

Views: 224

Answers (1)

Random Dev
Random Dev

Reputation: 52270

you should be able to get the data shown here by:

readData :: IO (Int, [Int])
readData = do
    [nr, _] <- map read . words <$> getLine
    nrs     <- map read . words <$> getLine
    return (nr,nrs)

this will read both lines and return the 10 as the first component and [1,4,8] as the second component of a tuple if you read in your example

As the second number in the first line will just be the length of the returned list I skipped it here.

of course you probably will want to adapt this to your needs.

Upvotes: 1

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