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  1. Practice
  2. Functional Programming
  3. Introduction
  4. Functions or Not?
  5. Discussions

Functions or Not?

  • matthias_a + 1 comment

    how do you know how many lines to read? In a situation where a user is inputting a variable set of inputs, would this work?

    If you run this it will just ask for inputs forever.

    also, I think that you don't need to define your own read if your run function has a definition run :: [Int] -> [String]

    • wirefox + 1 comment

      HackerRank tells you all you need to know about the input, so it's a completely different situation from an arbitrary CLI. This approach works for the type of problems on this particular site, and for the typical use case where input comes from a terminating program or a file.

      It actually won't run forever because of a handy thing called EOF.

      Nice idea about the type sig, though.

      • matthias_a + 1 comment

        how would you write 

        ms <- forM [1..n] $ const $ getLine
let d = M.fromList $ (\[x,y] -> (x,y)) . words <$> ms

        on one line?

        • wirefox + 0 comments
          d <- M.fromList <$> map ((\[x,y] -> (x,y)) . words) <$> replicateM n getLine