The FFI Addendum actually doesn't commit to which operations are in the class. It just says defines all these ops to have a context `Bits a', which is definitely the case. In other words, you proposed implementation is valid by the spec and your argument for it makes sense to me.
The spec really ought to say what the member functions of the class are, if we expect people to be able to define their own instances of Bits, and I don't see why we shouldn't allow that. I think Malcolm's proposed change looks reasonable, although there was probably a reason why these functions weren't made class members in the first place. Alastair: it was your design originally I believe, any thoughts? I think it would be a small optimisation in GHC too, at least for shifts by non-constant amounts. Cheers, Simon
Alastair: it was your design originally I believe, any thoughts?
Actually, I think it was Lennart's - though he might disown our variant... The change seems fine. (Actually, it feels a bit like another instance of defining the language to allow particular optimizations in particular technology... but I can only hold up progress for so long :-) -- A
"Simon Marlow"
The FFI Addendum actually doesn't commit to which operations are in the class. It just says defines all these ops to have a context `Bits a', which is definitely the case. In other words, you proposed implementation is valid by the spec and your argument for it makes sense to me.
The spec really ought to say what the member functions of the class are, if we expect people to be able to define their own instances of Bits, and I don't see why we shouldn't allow that.
True.
I think Malcolm's proposed change looks reasonable, although there was probably a reason why these functions weren't made class members in the first place. Alastair: it was your design originally I believe, any thoughts? I think it would be a small optimisation in GHC too, at least for shifts by non-constant amounts.
I applied Malcolm's change now. Manuel
participants (3)
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Alastair Reid -
Manuel M T Chakravarty -
Simon Marlow