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> To me unsafe generally means “memory safety or type safety is disabled”.

And that is exactly what it means. Unsafe functions in Haskell do run in production. They just subvert type safety (and I believe memory safety too, in the case of accursedUnutterablePerformIO).

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Even plain unsafePerformIO is memory-unsafe, as it will let you construct a polymorphic IORef, through which you can implement unsafeCoerce.

Hmm… is that memory-unsafe? I thought that came under the heading of ‘subverting the type system’. Then again, I suppose they’re more or less the same thing in a strongly-typed and pure language like Haskell.

Yes, it is very memory unsafe. Subverting the type system often the main source of memory unsafety in most languages. It typically means you can treat an arbitrary integer as a pointer to any other object.

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