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Comment by crntaylor | Hacker News Reader

Haskell:

  import System.Environment
  import Data.List

  main = do
    infile:outfile:_ <- getArgs
    input <- readFile infile
    writeFile outfile . unlines . sort . lines $ input

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It's a bit odd way of matching items of a list, I'd prefer to specify it without any possible trailing items:

    [infile, outfile] <- getArgs

Also, the last two lines may be squeezed into one (though less readable):

    writeFile outfile =<< (unlines . sort . lines) `fmap` readFile infile

On your first point; I was matching the behaviour of the C++ program in the blog post, which allows any number of command line arguments but only uses the first two.

On your second point, I actually thought about writing the whole thing as

  getArgs >>= \a -> readFile (a!!0) >>= writeFile (a!!1) . unlines . sort . lines

but decided that that's exactly the kind of thing that gets Haskell programmers a bad reputation.

Agreed, it does and you made the right choice. But in reality once you know Haskell - bind is a very common operation and reading this version is very natural.

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