6 Apr
2018
6 Apr
'18
6:07 a.m.
On Fri, 6 Apr 2018, Jon Purdy wrote:
One thing I like about the naturals with the “linked list” representation is that they’re lazy. When I was first learning Haskell, years ago, I expected something like “length xs > 1” to only evaluate “xs” up to the second constructor—that doesn’t work with “length” and “Int”, being strict, but it does work with “genericLength” and a lazy “Nat” (and “Ord” instance I guess).
It would also work with: void xs > replicate 1 ()