[friend_and_foe]

Well, I wrote a series of functions doing a bunch of mathematical calculations, making lists and that. But when I went to 1) read a file, 2) output results to a file, I ran into some trouble. This was for a real use case I had. Writing the code to do all the calculation was really enjoyable and pretty easy to pick up. Actually turning it into a useful program not so much.

I used no libraries and wrote all the math myself, because when I went to investigate libraries none of them seemed to explain what they do in language someone who didn't already know would understand. When I went in stackexchange and other community spaces I got similar results.

[simonmic]

It's normal to hit some walls, usually from lack of/difficulty in finding the right kind of intro material. (For example, with all respect to my esteemed sibling poster, their advice is overcomplicated.) I encourage you to try again. Laziness can get in the way of I/O, especially in small interactive programs. And Haskell can be written incrementally, once you know a few tricks. We'll be happy to help with "useful program" tips in chat (http://matrix.to/#/#haskell:matrix.org).

[mcguire]

That's exactly why I went through the exercise of translating Kernighan and Plauger's Software Tools in Pascal into Haskell.

https://web.archive.org/web/20171020034308/https://crsr.net/...

[kreyenborgi]

For reading line by line from stdin you can do something like

    import qualified Data.Text as T
    import qualified Data.Text.IO as T
    ...
    -- maybe you're reading things into a Set or something named acc
    go acc = do
      eof <- isEOF
      if eof then pure acc
      else do 
        line <- T.getLine
        T.putStrLn ("LINE IS "<>line)
        go (insert line acc)

There's hGetLine, hPutStrLn and hIsEOF for file handles, use withFile https://hackage.haskell.org/package/base-4.19.1.0/docs/Syste... which will close the handle when you exit the block. There are many more ways of doing this stuff of course, but the above will work fine for most stuff without any special libraries.

In general, use Data.Text for anything that you don't consider binary data (human-readable text as well as code, config files and such). Use Data.ByteString if you're thinking of it as pure encoded bytes.

[tome]

> When I went in stackexchange and other community spaces I got similar results

Could you post some examples of interactions you had on stackexchange? I'm interesting in improving the onboarding experience for new users, and knowing what do avoid will be helpful.