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IMHO mutable global state is totally fine if it is scoped to the current module or source file. Of course then it's not really 'global' anymore ;) Immutable gl

IMHO mutable global state is totally fine if it is scoped to the current module or source file. Of course then it's not really 'global' anymore ;) Immutable global state is fine to be accessible from the whole code base. Pure functions are best of course, but you can't build real-world things entirely from pure functions. The problematic approach lives somewhere inbetween, passing context/object references into deep callstacks isn't really a good solution for anything.

louthy 2y ago
> Pure functions are best of course, but you can't build real-world things entirely from pure functions. That's just plain wrong. There's even a language built entirely around pure functions: Haskell.
- flohofwoe 2y ago
  How do you talk to typical OS-, IO- or GUI-APIs (which all essentially represent global mutable state) in Haskell with pure functional code?
  - louthy 2y ago
    via the IO monad.
  - IsTom 2y ago
    A toy mental model could be e.g. a function that takes OS/IO/GUI events and produces actions (which are then executed by the caller) and then iterate it as long as the program runs. This function in itself can be pure.