24 Mar
2011
24 Mar
'11
12:46 p.m.
On Thu, Mar 24, 2011 at 12:21:57PM -0400, Amitava Shee wrote:
Hello Haskell gurus,
I am trying to understand "kind"
Prelude> :k Maybe Maybe :: * -> * Prelude> :k (->) (->) :: ?? -> ? -> *
What are the question marks? Why are they different from *?
I forget the precise details, but they are artifacts of GHC's internals. They have something to do with strictness and/or unboxing. You should really just think of them as if they were *.
How is this related to rank-2 polymorphism?
It isn't, as far as I know. -Brent