On Wed, Nov 19, 2008 at 8:06 PM, Dave Bayer
What I'm wondering, however, is if there is a way to code "minimum" efficiently in general,
minimum :: Ord a => [a] -> a
where one knows absolutely nothing further about the type "a", but one believes that lazy evaluation will run afoul of the above issue.
It would seem that this would require compiler support, allowing code to access approximations to lazy data generalizing the head of a lazy list. I'm reminded of working with power series by working mod x^n for various n. Here, I'd like a bounded version of "compare", that returned EQ for data that agreed to a specified lazy evaluation depth.
Did I miss that class? Is there a construct in GHC that would allow me to write "minimum" efficiently for lazy data?
One possibility would be to add minimum and maximum to Ord with the
appropriate default definitions, similar to Monoid's mconcat.
--
Dave Menendez