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Created by Simon Jakobi@sjakobiDeveloper

Documentation on instance Bits Integer should be improved

This instance is pretty special:

  • Most bit operations pretend to operate on a "fake 2's complement" form, despite this note in the Integer haddocks:

    Integers are stored in a kind of sign-magnitude form, hence do not expect two's complement form when using bit operations.

  • However popCount does not use the fake 2's complement form and instead returns negative results for negative Integers.

  • rotate = shift

  • The conversion from and to the fake 2's complement form incurs extra overhead for bit operations on negative numbers.

I think it would be good to document this in the haddocks of the Bits instance, and to remove or fix the note in the Integer haddocks.

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