3 ms·

> Why is it possible to "close" a file? i guess i would ask why it's possible to close a file that's going to be used after it's closed? will linear types[1] s

• dllthomas 7y ago
  > i guess i would ask why it's possible to close a file that's going to be used after it's closed? I don't think there's much reason to want to do it, but it's not obvious how to enforce that while still retaining the flexibility we'd want. Linear types expand the solution space, to be sure. Whether they "solve this" depends a bit on exactly what we consider the problem to be.
• AnimalMuppet 7y ago
  The file isn't going to be used after it's closed. The string from the file is going to be used after the file is closed. But with lazy IO, you don't have (all of) the string from the file yet, even though you've "read" it. That is, the abstractions don't do what non-Haskell abstractions would lead you to expect.
  • dllthomas 7y ago
    Right. The whole point of lazy IO is that you hide the actual IO behind values that don't appear to be IO. That means your use of the file isn't visible to the type system, so it's not really reasonable to expect it to prevent it. Unless I miss something, you can't write lazy IO without lying to the type system anyway (unsafePerformIO).