Evan Laforge wrote:
get_int sym = fmap ambi_int (lookup sym ambi_table :: Maybe (Ambi Maybe))
Of you and the type system you're the only one who knows that that value is
not used. The type system doesn't use (all) the rules you have in your mind.
It follows more simple ones.
You judge by values, not only types here. That is, you look at the value of
ambi_int and see that it's just 10 in your (value again) some_ambi. You see
that it's not
ambi_int = (some_return_from_monad ambi_monad) * 3
I'm not totally understanding, but I think you're saying that I could
write ambi_int in a way that it still had type "Ambi m -> Int" but
depended on the type of 'm'. I guess that makes sense, because it
could "run" m internally and return an Int based on the result, which
therefore depends on the type of 'm'.
It's more obvious with other type classes.
e.g. the snd of a value of type
(Num a) => (a, Bool)
Because what if the record/tuple was:
canOverflow = (ridiculous, ridiculous <= 4000000000)
ridiculous = 4000000000 ^ 5
Then it depends on whether you pick Int or Integer (or something else)
for "a", even if you only look at the Bool.
-Isaac
_______________________________________________
Haskell-Cafe mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/haskell-cafe
