On Wed, Apr 13, 2005 at 11:35:42AM +0100, Simon Marlow wrote:
> It's because unsafeRangeSize is supposed to have the same meaning as
> rangeSize. If someone defines an instance of Ix and overrides
> rangeSize, then unsafeRangeSize should continue to behave like rangeSize
> (remember, unsafeRangeSize isn't part of the exposed interface of
> Data.Ix, so clients of that interface can only define rangeSize).
The specification of rangeSize (Report + Erratum):
map index (range (l,u)) == [0..rangeSize (l,u) - 1]
constrains it (and unsafeRangeSize) fairly closely. The text seems to
imply that l and u are the first and last elements of range (l,u), i.e.
index (l,u) l == 0
index (l,u) u == rangeSize (l,u) - 1
which would make the default definition correct, and seems to imply that
it doesn't need to be a member function.
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