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A comment on John Carmack on Mutable Variables. Parent comment

Re:John Carmack on Mutable Variables by criddell on Friday October 31, 2025 @07:58AM (#45771052)
How does Haskell deal with things like memory-mapped I/O or signal handlers where the value of a variable can be changed by factors outside of the programmer's control?
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Re:John Carmack on Mutable Variables by how_gauche on Friday October 31, 2025 @08:58AM (#45771504)
Side effecting computations that depend on the "real world" go into an IO monad. The game in Haskell is shifting as much of the codebase as possible into pure functions/non-side-effecting code, because it's easier to reason about and prove correct.
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Re:John Carmack on Mutable Variables by chuckadams on Friday October 31, 2025 @09:41AM (#45771883)
IORefs usually, which can only be manipulated within the IO monad, so they tend to only get used at the top level and passed down to pure functions as parameters.
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