Re: [Haskell-cafe] Mystery operator?

On Mon, Nov 30, 2009 at 2:01 PM, michael rice wrote:

Hi all,

A lot of things posted here I wasn't aware of. My original example involved ~(x,y), so, returning to that context, how would these two simple cases vary:

add2 :: (Int,Int) -> Int add2 (x,y) = x+y

add2 :: (Int,Int) -> Int add2 ~(x,y) = x+y

I guess what I'm looking for is the concept that would dictate choosing one over the other.

These particular two functions are identical, because (+) is strict for Ints. But consider these two functions: swap ~(x,y) = (y,x) swap' (x,y) = (y,x) swap is non-strict, and swap' is strict. swap _|_ = (_|_, _|_) swap' _|_ = _|_ -- Dave Menendez http://www.eyrie.org/~zednenem/