3 ms·

> I'm baffled that Rust has mostly figured out that whole class of problem before Haskell Have you heard of `withFile`? https://www.stackage.org/haddock/lts-2

• Yoric 4y ago
  Note that a `Handle` can escape from `withFile` (unless perhaps this library has been updated to use linear types, I haven't followed Haskell in a while). That being said, even without linear types, it's much harder to accidentally leak a scoped value in Haskell than in most other programming languages, as the leak shows up in the type signature. /pedantic
  • tome 4y ago
    > Note that a `Handle` can escape from `withFile` Yes, this is true. If someone really wanted they could write a version that didn't using an ST-like type variable trick. I guess it hasn't been considered sufficiently necessary.
• ben0x539 4y ago
  Yeah, that's what my second gripe was meant to complain about. Really, withFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r is just a more general way of writing withFile :: FilePath -> IOMode -> (Handle -> IO Handle) -> IO Handle ;) I've also heard about the ResourceT monad transformer but as of right now I don't think I could explain what it does or judge how well it does it, maybe that's also a sufficient solution.
  • tome 4y ago
    Ah sure, fine, but see https://news.ycombinator.com/item?id=35345367 https://news.ycombinator.com/item?id=35345367