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John Carmack on mutable variables

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498 points azhenley | 1 comments | 31 Oct 25 02:34 UTC | HN request time: 0.247s | source
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y0ned4 ◴[31 Oct 25 09:22 UTC] No.45769960[source]▶
When I started programming in Haskell, where all variables are immutable, I felt like I was in a straitjacket

Then, suddenly, the enlightenment

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criddell ◴[31 Oct 25 11:58 UTC] No.45771052[source]▶
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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1. chuckadams ◴[31 Oct 25 13:41 UTC] No.45771883[source]▶
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.