On Fri, Dec 14, 2018 at 11:22:38AM +0000, Tom Ellis wrote:
On Fri, Dec 14, 2018 at 11:49:45AM +0100, Damien Mattei wrote:
another question with Haskell, again with my database but that is again related to Monads:
Damien, it's very hard to read your posts because they consist of snippets of code interspersed with commentary. You'll probably get much better responses if you post single, very small, well-formatted examples of sample code.
Anyway, the ultimate answer to your query is "use do-notation". Your getBS_WDS would be clearer written something like:
Ah, I see now why you were determined to use `fmap`. Seph recommended it to you I would avoid using do-notation at all until you’re a bit more comfortable with how monadic computations work, and how Haskell handles IO. To someone used to imperative programming, it can be more confusing that helpful, as it allows you to write something that looks and feels a lot like imperative code but differs from it in crucial ways. Get comfortable with using the monadic operators >> and >>= directly, and only then switch back to do-notation. Or don’t—personally I prefer not to use do-notation at all. -- Seph Shewell Brockway https://mail.haskell.org/pipermail/haskell-cafe/2018-December/130367.html I have to say I have completely the opposite position to Seph. If you try to write code in IO as a beginner without using do-notation you are in for a world of pain. Damien, I would suggest you write (very) small practice programs using both Seph's advice and mine and see which style you prefer and which helps you learn Haskell quicker. Tom