Johannes Waldmann [EMAIL PROTECTED] wrote:
For reference, in Java, ... there's nice syntactic sugar for looping
over collections: CollectionE c; for (E item : c) { ... }
I'd say this is an example of moving away from a left-biased
representation, or at least freeing the programmer from
Hello John,
Tuesday, February 28, 2006, 4:23:24 AM, you wrote:
i had plans to propose the same and even more:
instance C2 a b | a/=b
JM I was thinking it would be all kinds of useful if we had two predefined
JM classes
JM class Eq a b
JM class NEq a b
JM where Eq has instances exactly
instance C2 a b | a/=b
I was thinking it would be all kinds of useful if we had two predefined
classes
class Eq a b
class NEq a b
where Eq has instances exactly when its two types are equal and NEq has
instances exactly when its two types are not equal.
class Eq a b
instance Eq a a
Malcolm Wallace wrote:
Johannes Waldmann [EMAIL PROTECTED] wrote:
For reference, in Java, ... there's nice syntactic sugar for looping
over collections: CollectionE c; for (E item : c) { ... }
In Haskell, this is called 'fmap'. :-)
OK, then show me an instance Functor Set so that I can
Cale Gibbard wrote:
important point is that the elements and structure of the collection
are being constructed one at a time as you iterate over it, and they
are easily garbage collected as soon as you're done with them.
OK, I kind of buy that argument. Though the very word deforestation
Johannes Waldmann [EMAIL PROTECTED] wrote:
In Haskell, this is called 'fmap'. :-)
OK, then show me an instance Functor Set so that I can use it :-)
instance Function Set where
fmap = Data.Set.mapMonotonic
Ok, so this introduces a precondition on the function being mapped, so
there is
Malcolm Wallace wrote:
But if contexts-on-datatypes worked correctly,
data Set a = Ord a =
then even the real map from Data.Set:
map :: (Ord a, Ord b) = (a - b) - Set a - Set b
could be an instance method of Functor.
I'd love that. But I don't quite understand:
do you
Cale Gibbard wrote:
This change means that Rational is no longer a field. It makes me feel
uneasy at least. Should we really expect realToFrac to propagate those
values? Look at its type:
realToFrac :: (Real a, Fractional b) = a - b
Nothing about the Fractional class would seem to indicate
But if contexts-on-datatypes worked correctly,
data Set a = Ord a =
then even the real map from Data.Set:
map :: (Ord a, Ord b) = (a - b) - Set a - Set b
could be an instance method of Functor.
I'd love that. But I don't quite understand:
do you think this
Hello Claus,
Tuesday, February 28, 2006, 1:54:25 PM, you wrote:
CR class NEq a b
CR instance Fail a = NEq a a
CR instance NEq a b
i think that this definition just use ad-hoc overlapping instances
resolution mechanism that we want to avoid :)))
--
Best regards,
Bulat
On 28 February 2006 13:37, Lennart Augustsson wrote:
John Meacham wrote:
I mean, even a for loop in haskell is done as
mapM action [0..10]
I'd say _most_ uses of lists are deforested away because they are
used to express control and dataflow and arn't actually used as
persistant
Simon Marlow [EMAIL PROTECTED] wrote:
How does ENCODING work for a UTF-16 file, for example?
We don't know the file is UTF-16 until we read the ENCODING pragma,
and we can't read the ENCODING pragma because it's in UTF-16.
Use the same type of heuristic as XML uses (for instance).
* If
Malcolm.Wallace wrote:
(But then, how would you guarantee that the first three characters
in the file must be {-# ?)
In particular, what do you propose for literate source?
(I hardly have any .hs files.)
As far as I can see,
it seems to be possible to get LaTeX to work with UTF8;
the
On 28/02/06, John Meacham [EMAIL PROTECTED] wrote:
On Tue, Feb 28, 2006 at 12:44:04AM -0500, Cale Gibbard wrote:
I'm almost scared to ask: does this mean we need negative zero as well?
good point. probably.
This change means that Rational is no longer a field. It makes me feel
uneasy at
You addressed this to me -- but I'm an advocate for rather conservative
extensions whereas you are calling for extensions that go beyond what
any current implementation can do.
generally, that may be true,-) but in this specific case, I was just asking
for an effort to document the differences
On 2/28/06, Johannes Waldmann [EMAIL PROTECTED] wrote:
Malcolm Wallace wrote:
But if contexts-on-datatypes worked correctly,
data Set a = Ord a =
then even the real map from Data.Set:
map :: (Ord a, Ord b) = (a - b) - Set a - Set b
could be an instance method of
On 2/28/06, Ben Rudiak-Gould [EMAIL PROTECTED] wrote:
Simon Peyton-Jones wrote:
- A program that type checks can have its meaning changed by adding an
instance declaration
- Similarly adding import M() can change the meaning of a program (by
changing which instances are visible
-
Claus Reinke wrote:
most of us would be happy if instance contexts
would be required to uniquely determine the instance to be
chosen, a rather conservative extension of current practice.
I'm not so sure about the most of us, as you note yourself the
defaulting pattern is quite popular (and
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