17 Oct
2005
17 Oct
'05
10:36 a.m.
On 15 October 2005 19:08, Bulat Ziganshin wrote:
Hello Lennart,
Saturday, October 15, 2005, 5:03:50 PM, you wrote:
Alas, Haskell is more subtle than that. Which is why newtype exists.
Try case A _|_ of A _ -> 1 with the two versions of A to see the difference.
this have practical usage?? may be for such very special things strictness annotation will be enough??
The semantics of newtype are really decided by its implementation. The basic idea is that a newtype of T can be represented in the same way as T. Once you know this, it pretty much fixes what semantics you can expect - the semantics of a newtype of T must be the same as T, because the runtime cannot distinguish the two. Cheers, Simon