Derek Elkins wrote:
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Or http://www.cafepress.com/l_revolution
Paul.
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Richard O'Keefe wrote:
On 17 Oct 2008, at 9:53 am, Daryoush Mehrtash wrote:
So does this mean that the reason for complexity of generics is the
Java inheritance?
No. The reason for the complexity of generics in Java is that
they weren't designed into the language in the first place.
It
The best analogy I have found on Monads (written for Scala) is the one that
compared them to Elephants. The author was referring the the blind men and
elephant story: http://en.wikipedia.org/wiki/Blind_Men_and_an_Elephant
On Wed, Oct 15, 2008 at 6:40 PM, Derek Elkins [EMAIL PROTECTED]wrote:
On Thu, 2008-10-16 at 15:02 +1300, Richard O'Keefe wrote:
On 16 Oct 2008, at 12:09 pm, Jonathan Cast wrote:
I am not sure how say in a Java language a constructor can conjure
up
a value of an unknown type.
Well, that's the point. It can't, in Haskell or in Java. If you
understand
On Thu, 2008-10-16 at 15:02 +1300, Richard O'Keefe
wrote:
On 16 Oct 2008, at 12:09 pm, Jonathan Cast wrote:
I am not sure how say in a Java language a
constructor can conjure
up
a value of an unknown type.
Well, that's the point. It can't, in
Haskell or in Java. If you
On Thu, 2008-10-16 at 09:48 -0700, Robert Greayer wrote:
On Thu, 2008-10-16 at 15:02 +1300, Richard O'Keefe
wrote:
On 16 Oct 2008, at 12:09 pm, Jonathan Cast wrote:
I am not sure how say in a Java language a
constructor can conjure
up
a value of an unknown type.
--- On Thu, 10/16/08, Jonathan Cast [EMAIL PROTECTED] wrote:
Can I have HashSetInteger? Could I construct
HashSet?, if I did?
Yes:
HashSet? blah = (HashSet?) hashSetClass.newInstance();
... compiles, and won't throw an exception if hashSetClass truly is the class
object for HashSet.
On Thu, 2008-10-16 at 10:02 -0700, Robert Greayer wrote:
--- On Thu, 10/16/08, Jonathan Cast [EMAIL PROTECTED] wrote:
Can I have HashSetInteger? Could I construct
HashSet?, if I did?
Yes:
HashSet? blah = (HashSet?) hashSetClass.newInstance();
... compiles, and won't throw an
--- On Thu, 10/16/08, Jonathan Cast [EMAIL PROTECTED] wrote:
But I can't say new HashSet?()?
No... but you can say 'new HashSetT()' where T is a type variable, and then
put a value of type T into your set, which is probably generally what you want.
HashSet? is a set of unknown (at
On Thu, 2008-10-16 at 11:41 -0700, Robert Greayer wrote:
--- On Thu, 10/16/08, Jonathan Cast [EMAIL PROTECTED] wrote:
But I can't say new HashSet?()?
No... but you can say 'new HashSetT()' where T is a type variable,
and then put a value of type T into your set, which is probably
--- On Thu, 10/16/08, Jonathan Cast [EMAIL PROTECTED] wrote:
So if I say
void wrong(List? foo, List? bar)
I get two /different/ type variables implicitly filled in?
If I declare a generic class, and then have a method, is
there a way, in
that method's parameter list, to say `the type
On Thu, 2008-10-16 at 12:27 -0700, Robert Greayer wrote:
--- On Thu, 10/16/08, Jonathan Cast [EMAIL PROTECTED] wrote:
So if I say
void wrong(List? foo, List? bar)
I get two /different/ type variables implicitly filled in?
If I declare a generic class, and then have a method, is
So does this mean that the reason for complexity of generics is the Java
inheritance?
BTW, in addition to the article I posted, This site:
http://www.angelikalanger.com/GenericsFAQ/JavaGenericsFAQ.html has a FAQ
on Java generics that is 500+ pages long! In Haskell you have
parametrized
On Thu, 2008-10-16 at 13:53 -0700, Daryoush Mehrtash wrote:
So does this mean that the reason for complexity of generics is the
Java inheritance?
BTW, in addition to the article I posted, This site:
http://www.angelikalanger.com/GenericsFAQ/JavaGenericsFAQ.html has a
FAQ on Java generics
derek.a.elkins:
On Thu, 2008-10-16 at 13:53 -0700, Daryoush Mehrtash wrote:
So does this mean that the reason for complexity of generics is the
Java inheritance?
BTW, in addition to the article I posted, This site:
http://www.angelikalanger.com/GenericsFAQ/JavaGenericsFAQ.html has a
On Thu, 2008-10-16 at 16:25 -0500, Derek Elkins wrote:
On Thu, 2008-10-16 at 13:53 -0700, Daryoush Mehrtash wrote:
So does this mean that the reason for complexity of generics is the
Java inheritance?
BTW, in addition to the article I posted, This site:
On 17 Oct 2008, at 9:53 am, Daryoush Mehrtash wrote:
So does this mean that the reason for complexity of generics is the
Java inheritance?
No. The reason for the complexity of generics in Java is that
they weren't designed into the language in the first place.
It took several attempts and
Janis Voigtlaender wrote:
Derek Elkins wrote:
Agreed. I'm extremely tired of the I haven't heard this term therefore
it must be 'scary' and complicated and beyond me attitude. Such people
need to stop acting like five year old children.
Not that it has much to do with the debate, but the
I'd like to thank everyone who replied to my OP, and also perhaps
clarify one point. I wasn't trying to be argumentative or negative
about any work people have done to make Haskell approachable for OO
programmers (or any other programmers, for that matter). I simply
wanted to know what others
On Wed, Oct 15, 2008 at 8:08 AM, John Lato [EMAIL PROTECTED] wrote:
I'd like to thank everyone who replied to my OP, and also perhaps
clarify one point. I wasn't trying to be argumentative or negative
about any work people have done to make Haskell approachable for OO
programmers (or any
The (=) operation for the state monad can be implemented with no
understanding at all.
Just watch djinn make the code for it. And djinn doesn't understand
the state monad, I promise. :)
-- Lennart
2008/10/15 David Leimbach [EMAIL PROTECTED]:
On Wed, Oct 15, 2008 at 8:08 AM, John Lato
Hello David,
Wednesday, October 15, 2008, 7:16:09 PM, you wrote:
I've read a lot of the Monad tutorials, and I feel like I only get
most of it to be 100% honest. The State Monad still boggles my
mind a little bit. I understand what it's supposed to do and I get
the idea about how it works.
PROTECTED] On Behalf Of David Leimbach
Sent: 15 October 2008 4:16 pm
To: John Lato
Cc: haskell-cafe@haskell.org
Subject: Re: [Haskell-cafe] Re: What I wish someone had told
me...
On Wed, Oct 15, 2008 at 8:08 AM, John Lato [EMAIL PROTECTED]
wrote
Albet Lai wrote:
John Lato wrote:
Are you advocating introducing existential types to beginning
Haskellers? I think something with the scary name existential
quantification would greatly increase the head'splodin' on the
learnin' slope.
OOP(*) advocates introducing existential types to
The instance selection for an interface is done at run-time and this is
inherently necessary. The instance (in a different sense) selection for
type classes is almost always resolvable statically. In Haskell 98
In both cases, the dispatch is inherently dynamic, and in both cases,
most
leaders and pioneers: if you know one language, picking up others
should be easy, they just differ in syntax.
I have heard it, and I used to believe it. Now I think it's only true
provided the one language you know is suitably advanced (and currently
non-existent, I think).
It all depends
The equivalent won't compile in Haskell, because the actual return
type does matter, and *is determined by the calling code*. Our
fictional GetListOfData can't return a List or a Mylist depending on
some conditional, in fact it can't explicitly return either one at
all, because the actual
On Wed, 2008-10-15 at 11:56 -0700, Daryoush Mehrtash wrote:
The equivalent won't compile in Haskell, because the actual
return
type does matter, and *is determined by the calling code*.
Our
fictional GetListOfData can't return a List or a Mylist
Would you please explain this a bit more:
the various
unfortunate consequences of type erasure in Java are avoided by the fact
that Haskell types lack constructors, so the user never expects to be
able to conjure up a value of an unknown type.
Thanks,
daryoush
On Wed, Oct 15, 2008 at 12:04
Hello Daryoush,
Wednesday, October 15, 2008, 10:56:39 PM, you wrote:
If you notice java generics has all sort of gotchas (e.g.
http://www.ibm.com/developerworks/java/library/j-jtp01255.html). I
large prob;em of OOP languages with generics is interaction between
those two types of
I am having hard time understanding this statement:
Haskell types lack constructors, so the user never expects to be
able to conjure up a value of an unknown type.
I am not sure how say in a Java language a constructor can conjure up a
value of an unknown type.
daryoush
On Wed, Oct 15, 2008
Daryoush Mehrtash wrote:
I have had an unresolved issue on my stack of Haskell vs Java that I wonder
if your observation explains.
If you notice java generics has all sort of gotchas (e.g.
http://www.ibm.com/developerworks/java/library/j-jtp01255.html). I somehow
don't see this discussion in
On Wed, 2008-10-15 at 13:01 -0700, Daryoush Mehrtash wrote:
I am having hard time understanding this statement:
Haskell types lack constructors, so the user never expects to
be
able to conjure up a value of an unknown type.
I am not sure how say in a Java language
On Wed, 2008-10-15 at 14:45 -0400, Stefan Monnier wrote:
The instance selection for an interface is done at run-time and this is
inherently necessary. The instance (in a different sense) selection for
type classes is almost always resolvable statically. In Haskell 98
In both cases, the
On Wed, 2008-10-15 at 08:16 -0700, David Leimbach wrote:
On Wed, Oct 15, 2008 at 8:08 AM, John Lato [EMAIL PROTECTED] wrote:
I'd like to thank everyone who replied to my OP, and also
perhaps
clarify one point. I wasn't trying to be argumentative or
negative
On 16 Oct 2008, at 9:01 am, Daryoush Mehrtash wrote:
I am not sure how say in a Java language a constructor can conjure
up a value of an unknown type.
... Class anUnknownClass;
Object anInstance;
anInstance = anUnknownClass.getConstructor().newInstance();
If you know that the
On 16 Oct 2008, at 12:09 pm, Jonathan Cast wrote:
I am not sure how say in a Java language a constructor can conjure
up
a value of an unknown type.
Well, that's the point. It can't, in Haskell or in Java. If you
understand that --- that you can't call the default constructor of a
class
Would you please explain this a bit more:
the various unfortunate consequences of type erasure in Java are
avoided by the fact that Haskell types lack constructors, so the user
never expects to be able to conjure up a value of an unknown type.
Even if Haskell had Java-style constructors, it
While this may be true, it's missing the point. The claim that type
classes are like interfaces (the usual argument is that they define an
interface, but not an implementation) misleads OO-grounded programmers
into thinking of type classes in terms of an already-familiar concept.
This is bad
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