Re: [Haskell-cafe] 0/0 > 1 == False
Cristian Baboi wrote:
I think this should be put this way: Bottom is a part of the semantic domain which is not Haskell.
Rather, something outside Haskell that describes what Haskell programs mean. Yes.
In the semantic domain there is one bottom. In Haskell there are many expressions that represent bottom. One cannot test those for equality.
Yes.
The result of a Haskell function applied to some arguments cannot be bottom.
I think you mean that they cannot be bottom if you want to compare them for equality. Yes. -Yitz
"Yitzchak Gale"
In the semantic domain there is one bottom. In Haskell there are many expressions that represent bottom. One cannot test those for equality.
If we are being pedantic, I can define data Foo = Foo instance Eq Foo where _ == _ = True (undefined :: Foo) == Foo --> True
The result of a Haskell function applied to some arguments cannot be bottom.
This function is bottom for any argument: f x = undefined
I think you mean that they cannot be bottom if you want to compare them for equality. Yes.
See above. What is the precise term for describing this? Structural equality? On the other hand, some bottoms are exceptions, you may be able to catch them and do something useful with them after all, no? How does that fit in? -k -- If I haven't seen further, it is by standing in the footprints of giants
On Thu, 10 Jan 2008, Ketil Malde wrote:
I think you mean that they cannot be bottom if you want to compare them for equality. Yes.
See above. What is the precise term for describing this? Structural equality?
On the other hand, some bottoms are exceptions, you may be able to catch them and do something useful with them after all, no? How does that fit in?
Catching errors is a hack: http://www.haskell.org/haskellwiki/Error http://www.haskell.org/haskellwiki/Exception
participants (3)
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Henning Thielemann -
Ketil Malde -
Yitzchak Gale