On 25 Jan 2009, at 23:36, Daniel Fischer wrote:
Why is this obvious - I would argue that it's "obvious" that bottom *is* () - the data type definition says there's only one value in the type. Any value that I haven't defined yet must be in the set, and it's a single element set, so it *must* be ().
It's obvious because () is a defined value, while bottom is not - per definitionem. The matter is that besides the elements declared in the datatype definition, every Haskell type also contains bottom. -----
I thought that under discussion were the actual Haskell semantics - I'm not so sure about that anymore. If Thomas Davie (Bob) was here discussing an alternative theory in which () is unlifted, the sorry, I completely misunderstood.
My "argument" is that in Haskell as it is, as far as I know, _|_ *is* defined to denote a nonterminating computation, while on the other hand () is an expression in normal form, hence denotes a terminating computation, therefore it is obvious that the two are not the same, as stated by Jake. Of course I may be wrong in my premise, then, if one really cared about obviousness, one would have to put forward a different argument.
If you go look through the message history some more, you'll see a couple of emails which convinced me that that indeed was the semantics in haskell, and a follow up saying "okay, lets discuss a hypothetical now, because this looks fun and interesting." Bob