~ patterns

[Simon Peyton-Jones]

| BTW if let and where were strict-by-default, just as lambda and case
| are, then there would be no need for ! patterns, would there?
| 
| John

Yes, absolutely there would, but really only on variables.  
	f (!x, !y) = e
(Dually, you could argue that with let lazy-by-default there is no need
for ~ patterns.)

Simon