[fiddlerwoaroof]

Except this isn’t true. I can embed arbitrary side effects in any line of Haskell code with something like

    foo :: Int -> String
    foo x = seq
            (unsafePerformIO $
              println “pwned”)
            (show x)

[kqr]

Yes, we know unsafePerformIO exists, but nobody really uses it, it's clearly "unsafe", you can have your build chain scream at its occurrence, and... fast and loose reasoning is morally correct[1].

[1]: https://dl.acm.org/doi/10.1145/1111320.1111056

[chriswarbo]

FYI this sort of 'backdoor' can be forbidden using the "safe haskell" extension in GHC:

https://downloads.haskell.org/~ghc/latest/docs/html/users_gu...