type families & type-level recursion
Manuel M T Chakravarty
chak at cse.unsw.edu.au
Thu Oct 23 19:35:28 EDT 2008
> Manuel M T Chakravarty wrote:
>> Peter Gavin:
>>> > instance ( NaturalT n
>>> > , zero ~ (n :==: D0)
>>> > , zero ~ True )
>>> > => TestIter n True where
>>> > testIter _ _ = ""
>> I am wondering why you are writing (zero ~ (n :==: D0), zero ~
>> True) instead os just (True ~ (n :==: D0)) - after all zero appears
>> nowhere else.
> Well, it's not happening in this instance, but I had some other code
> that would give me compilation warnings unless I flattened
> everything out like that. I don't recall what the message exactly
> was anymore, but I'd never seen it before. I guess I just got into
> the habit of doing that without really thinking about it.
The earlier problems you head may have been due to a bug in the
preliminary versions. If you find that it makes a difference in the
current implementation, then please let us know.
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