Every computing culture is different. Being in the habit of asking questions you should be able to answer yourself is not a good idea. Why did you ask a question which you yourself characterize as "ignorant"? Although Haskell comm. is necessarily welcoming due to the learning curve and lack of popular adoption there are limits here too. On Tue, May 24, 2011 at 5:34 AM, max ulidtko wrote:

2011-05-23 22:10 -0700, Gregory Crosswhite:

...

Hey everyone,

Okay, this will sound silly, but I ventured into the Scala mailing list recently and asked an ignorant question on it, and I was shocked when people reacted not by enlightening me but by jumping on me and reacting with hostility.  I bring this up not to badmouth the Scala community (they are apparently going through growing pains and will hopefully mature with time!) but just because it made me appreciate just how awesome you guys are, so I just feel the need to publicly express my admiration and thank to everyone on this list for having fostered such an incredibly professional, fanatically nonhostile, and generally pleasant place to talk about Haskell!!!

*GROUP HUG*

Okay, I'm done now.  :-)

Cheers, Greg

Wow. I subscribed to the list just an hour ago or so, and already receiving hugs! That's kinda... striking, you know.

Yay! Newbie hug to everyone too!

--------- max ulidtko

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-- =============================================== juan@acm.org | Juan.Daugherty on Skype | 01 716 524 0542 =============================================== -------PGP SIGNATURE Attached If Signed-------=

Why did you ask a question which you yourself characterize as "ignorant"?

Juan, I think it is the kind of question whose answer is obvious to people with at least a little practice of the language. For instance, one of my friends asked me once why the operation of calculating the length of list has an O(n) complexity, since to his opinion, you could just store the size inside the list and increment it when elements are appended. Once you got the clue about lazy lists, the answer is obvious [1], but to a Java-trained mind, it is right it can at first sight seem like a lack of optimisation. I'm curious Gregory, what was the question you asked and how were you brushed off? And what are those troubles the Scala community is undergoing? It would be a real shame if the Scala community wasn't up to its terrific language... [1] And if it is not, then to find it your homework shall be ;) 2011/5/24 Juan Daugherty

Every computing culture is different. Being in the habit of asking questions you should be able to answer yourself is not a good idea. Why did you ask a question which you yourself characterize as "ignorant"? Although Haskell comm. is necessarily welcoming due to the learning curve and lack of popular adoption there are limits here too.

On Tue, May 24, 2011 at 5:34 AM, max ulidtko wrote:

...

2011-05-23 22:10 -0700, Gregory Crosswhite:

...

Hey everyone,

Okay, this will sound silly, but I ventured into the Scala mailing list recently and asked an ignorant question on it, and I was shocked when people reacted not by enlightening me but by jumping on me and reacting with hostility. I bring this up not to badmouth the Scala community (they are apparently going through growing pains and will hopefully mature with time!) but just because it made me appreciate just how awesome you guys are, so I just feel the need to publicly express my admiration and thank to everyone on this list for having fostered such an incredibly professional, fanatically nonhostile, and generally pleasant place to talk about Haskell!!!

*GROUP HUG*

Okay, I'm done now. :-)

Cheers, Greg

Wow. I subscribed to the list just an hour ago or so, and already receiving hugs! That's kinda... striking, you know.

Yay! Newbie hug to everyone too!

--------- max ulidtko

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-- =============================================== juan@acm.org | Juan.Daugherty on Skype | 01 716 524 0542 =============================================== -------PGP SIGNATURE Attached If Signed-------=

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Yves Parès writes:

For instance, one of my friends asked me once why the operation of calculating the length of list has an O(n) complexity, since to his opinion, you could just store the size inside the list and increment it when elements are appended.

Then tell me, why does calculating the length of a (Haskell) list has O(n) complexity. I could just store the length of the list - as an additional argument to the "Cons" constructor that is automatically initialized on construction (and you never need to change it later, since Haskell objects are "immutable", in the words of Java programmers) In Haskell, the reason for not doing this (besides simplicity, and inertia) actually is (I think) laziness: you don't want to evaluate the "length" field of the second argument of the "cons" prematurely. Well, unless you look at the "length" field of the constructed object, it won't be evaluated, but a pile of thunks will be constructed instead, and I think that's what you really want to avoid. On the other hand, there are implementations of strict sequences with an O(1) size implemenation. http://hackage.haskell.org/packages/archive/containers/0.4.0.0/doc/html/Data... J.W.

On 24 May 2011 13:41, Johannes Waldmann wrote:

I could just store the length of the list - as an additional argument to the "Cons" constructor that is automatically initialized on construction (and you never need to change it later, since Haskell objects are "immutable", in the words of Java programmers)

In Haskell, the reason for not doing this (besides simplicity, and inertia) actually is (I think) laziness: you don't want to evaluate the "length" field of the second argument of the "cons" prematurely.

Neither OCaml nor PLT Scheme cache the length or they didn't a year of two ago when someone asked this question on the Haskell Beginners list and I checked the respective source trees. As the PLT Scheme list was implemented in C at the time (maybe it still is?) I was a bit surprised by this.

Evan Laforge schrieb:

I dunno, I hardly ever use length and when I do it's always lists I know are very short. And it tends to be shortcuts like 'drop (length prefix) word' because I'm too lazy to write a special function.

Since it happens so often I have written such functions: http://hackage.haskell.org/packages/archive/utility-ht/0.0.7/doc/html/Data-L...

On the catMaybes thing, I have a function 'mapMaybe = Maybe.catMaybes . map'. I turns out I only ever used catMaybes after mapping a Maybe function, so I hardly ever use catMaybes anymore. I suppose it should have been maybeMap for consistency with concatMap.

mapMaybe is part of Data.Maybe.

On Tue, May 31, 2011 at 11:31 AM, Ozgur Akgun wrote:

Evan, On 24 May 2011 19:57, Evan Laforge wrote:

...

On the catMaybes thing, I have a function 'mapMaybe = Maybe.catMaybes . map'.  I turns out I only ever used catMaybes after mapping a Maybe function, so I hardly ever use catMaybes anymore.  I suppose it should have been maybeMap for consistency with concatMap.

Just wanted to point out, that function is already defined in Data.Maybe: http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-Maybe.... Hugs :)

Indeed it is, somehow I missed that one and wrote my own instead.

"Richard O'Keefe" writes:

...

Then tell me, why does calculating the length of a (Haskell) list has O(n) complexity.

Because it is a rather rare operation and the cost of doing this would be far higher than you think.

I suspect that if you store the length non-strictly, it would build up thunks, causing a stack overflow when evaluated. If it is strict, it would make a lot of operations that are O(1) today into O(n) operations. -k -- If I haven't seen further, it is by standing in the footprints of giants

On 24/05/11 22:41, Johannes Waldmann wrote:

Then tell me, why does calculating the length of a (Haskell) list has O(n) complexity. Infiniticity aside, tail would become O(n) if you store a length with each cons cell.

-- Tony Morris http://tmorris.net/

On 25/05/11 16:46, Eugene Kirpichov wrote:

data FList a = FNil | FCons Int a (FList a) empty = FNil len FNil = 0 len (FCons n _) = n cons x xs = FCons (1 + len xs) x xs tail (FCons _ _ xs) = xs My mistake, sorry. Currently looking for original reason to have accidentally come to believe that.

-- Tony Morris http://tmorris.net/

Juan Daugherty writes:

Every computing culture is different.

Definitely. I've just given up on several "cultures" which are just too vitriolic. Scala is on my list of interesting stuff to look at some day, but if I'm going to be flamed for asking questions about the language, I can easily find something else to fill my time with.

Being in the habit of asking questions you should be able to answer yourself is not a good idea.

Maybe not. Is it a good idea to flame people who do this? If you look at two case studies: the Scala thread where Gregory was involved, and the recent mail here, basically asking for 'catMaybes'. Replying "whoosh", or otherwise producing non-informative, arrogant feedback results in a long thread, culminating in a more useful answer, as well as a lot of noise. Replying with a pointer to 'catMaybes' resulted in (most likely) the author going off to finish/improve his program, and some more interesting discussion on alternative ways to do this. The point is that at face value, being rude and arrogant may drive away naive questions, but is much more likely to result in endless threads of discussions of etiquette, usually laced with ample amounts of hostility. This actually decreases signal to noise. Also it not only drives away the naive questions, it drives away the people asking them. People who might at some point become informed, contributing members of the community. I don't know, maybe Scala is big enough that they can afford to behave that way. Some people quit haskell-cafe for other (better policed?) forums, so perhaps we are too liberal? I hope not.

Although Haskell comm. is necessarily welcoming due to the learning curve and lack of popular adoption there are limits here too.

My theory is that flaming cultures arise around people who are technically brilliant, but somewhat lacking socially, either through arrogance or ineptitude. Members of communities where such people become central respect them for their brilliance, and then emulate, echo or support them. (I guess the implicit rationale is that if the smart people are assholes, being an asshole will make people - or myself - think I'm smart, too). Why have we managed to avoid this? Partly because of the heavy academic slant, usually academia tends to reserved politeness. Also, there's a lot of theory floating around, so although I might get impatient with some people, I can't really grow arrogant, since there's so *much* I'm obviously completely ignorant at. (Sorry about the long off-topic rant.) -k -- If I haven't seen further, it is by standing in the footprints of giants

Firstly, I would definitely like to second the group hug! I'd say best learning community on the net, that I know of. On 5/24/11, Ketil Malde wrote:

The point is that at face value, being rude and arrogant may drive away naive questions, but is much more likely to result in endless threads of discussions of etiquette, usually laced with ample amounts of hostility. This actually decreases signal to noise.

Also it not only drives away the naive questions, it drives away the people asking them. People who might at some point become informed, contributing members of the community.

It also drives away people who don't know if their question is naive or not. When you don't want to be yelled at, you have a strong tendency to err on the side of not asking. This slows down learning significantly, and decreases the number of people who can answer others' questions in the future.

Some people quit haskell-cafe for other (better policed?) forums, so perhaps we are too liberal? I hope not.

Does anybody know how much this has happened? I'm very interested in how we can maintain this amazing resource as Haskell's user base grows. Will the same etiquette work when we start to get lots of questions from Java programmers? :) Tom

fluency in Scala is an industry asset, since it runs in the Java VM, while Haskell is an academic asset as well as a fun asset. The value of an industry asset grows with the lack of competence of others. Therefore competing guys are not welcome. There are enoug crocodiles in the pond. Alberto. 2011/5/24 Ketil Malde :

Juan Daugherty writes:

...

Every computing culture is different.

Definitely.  I've just given up on several "cultures" which are just too vitriolic.  Scala is on my list of interesting stuff to look at some day, but if I'm going to be flamed for asking questions about the language, I can easily find something else to fill my time with.

...

Being in the habit of asking questions you should be able to answer yourself is not a good idea.

Maybe not.

Is it a good idea to flame people who do this?

If you look at two case studies: the Scala thread where Gregory was involved, and the recent mail here, basically asking for 'catMaybes'.

Replying "whoosh", or otherwise producing non-informative, arrogant feedback results in a long thread, culminating in a more useful answer, as well as a lot of noise.

Replying with a pointer to 'catMaybes' resulted in (most likely) the author going off to finish/improve his program, and some more interesting discussion on alternative ways to do this.

The point is that at face value, being rude and arrogant may drive away naive questions, but is much more likely to result in endless threads of discussions of etiquette, usually laced with ample amounts of hostility.  This actually decreases signal to noise.

Also it not only drives away the naive questions, it drives away the people asking them.  People who might at some point become informed, contributing members of the community.

I don't know, maybe Scala is big enough that they can afford to behave that way.  Some people quit haskell-cafe for other (better policed?) forums, so perhaps we are too liberal?  I hope not.

...

Although Haskell comm. is necessarily welcoming due to the learning curve and lack of popular adoption there are limits here too.

My theory is that flaming cultures arise around people who are technically brilliant, but somewhat lacking socially, either through arrogance or ineptitude.  Members of communities where such people become central respect them for their brilliance, and then emulate, echo or support them.  (I guess the implicit rationale is that if the smart people are assholes, being an asshole will make people - or myself - think I'm smart, too).

Why have we managed to avoid this?  Partly because of the heavy academic slant, usually academia tends to reserved politeness.  Also, there's a lot of theory floating around, so although I might get impatient with some people, I can't really grow arrogant, since there's so *much* I'm obviously completely ignorant at.

(Sorry about the long off-topic rant.)

-k -- If I haven't seen further, it is by standing in the footprints of giants

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"come on! it's fun! i can write foldr with foldl!"

And when you try to explain that to your java-ITC-formatted friends, they utterly surprisingly seem not to care about it ^^ 2011/5/31 Adrien Haxaire

Le 31/05/2011 21:15, Alberto G. Corona a écrit :

Haskell is an academic asset as well as a fun asset.

...

I fully agree. These are two of the three reasons which made me choose haskell as the functional language to learn. Coding fortran all day, I wanted a new approach on programming. The strong scientific roots of haskell would give me stuff to learn and discover for a lot of time. The atmosphere/halo around haskell was intriguing too: "come on! it's fun! i can write foldr with foldl!" is not the kind of enthusiasm I was used too :)

The third reason is, as you already now, the community. Never have seen so much encouragements, help, time, humility, jokes,... crossing the gap takes some time, but when you feel that lots of people are glad you're here, it's just constant joy.

group hug !

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On Wed, 01 Jun 2011 11:46:36 +0200, Henning Thielemann wrote:

Really, you can write foldr in terms of foldl? So far I was glad I could manage the opposite direction.

i didn't try it, that was just an example of how strange/interesting the enthusiasm appeared to me when i started Haskell. good exercise though, as even if it cannot be done (for which i have no clue), the explanation of it is interesting too.

On Wed, Jun 1, 2011 at 3:28 AM, Daniel Fischer < daniel.is.fischer@googlemail.com> wrote:

On Wednesday 01 June 2011 12:25:06, Adrien Haxaire wrote:

...

On Wed, 01 Jun 2011 11:46:36 +0200, Henning Thielemann wrote:

...

Really, you can write foldr in terms of foldl? So far I was glad I could manage the opposite direction. foldr (++) (repeat "No way! ")

How about this: myFoldr :: (a -> b -> b) -> b -> [a] -> b myFoldr f z xs = foldl' (\s x v -> s (x `f` v)) id xs $ z Cheers, Ivan

http://stackoverflow.com/questions/6172004/writing-foldl-using-foldr/6172270... Thank Graham Hutton and Richard Bird. On Wed, Jun 1, 2011 at 7:12 PM, Tom Murphy wrote:

...

How about this:

myFoldr :: (a -> b -> b) -> b -> [a] -> b myFoldr f z xs = foldl' (\s x v -> s (x `f` v)) id xs $ z

Cheers, Ivan

Great! Now I really can say "Come on! It's fun! I can write foldr with foldl!"

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On Thursday 02 June 2011 01:12:37, Tom Murphy wrote:

...

How about this:

myFoldr :: (a -> b -> b) -> b -> [a] -> b myFoldr f z xs = foldl' (\s x v -> s (x `f` v)) id xs $ z

Cheers, Ivan

Great! Now I really can say "Come on! It's fun! I can write foldr with foldl!"

Unfortunately, you can't, not quite. A left fold cannont return anything before it has reached the end of the list, so it doesn't work on infinite lists. With a suitable combining function (and suitable input), a right fold can start delivering the result early, hence right folds (can) produce results for infinite lists (and my example was meant to draw attention to that fact). Cheers, Daniel

"Alberto G. Corona " wrote:

Haskell is an academic asset as well as a fun asset.

I cannot agree with this for practical reasons. I'm using Haskell for real world commercial applications, and I'm very productive with it. There is however a variation of this statement, with which I could agree, namely: Learning Haskell will pay off much less than learning PHP, if your goal is to find a job. It takes a lot longer and there are a lot less companies in need of Haskell programmers. Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/

Yves Parès wrote:

...

I cannot agree with this for practical reasons. I'm using Haskell for real world commercial applications, and I'm very productive with it.

I wish so much I could say that... Out of curiosity, what are you using Haskell for?

I use the Yesod web framework for web development and a combination of many libraries for network servers. Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/

I got hired at a company because one of the interviewers was impressed that I taught myself Haskell. I basically never use it at work, but I did in my old job. Dave On Thu, Jun 2, 2011 at 2:23 PM, Michael Litchard wrote:

I disagree. I'm by no means proficient in Haskell. And, I never bothered learning PHP. I will when I need to. PHP programmers are a dime a dozen. It's been my experience that Haskell is a tool one may use to distinguish oneself from the hoi-poloi. This is important when you live in an area where the baker down the street has a CS degree.

On Thu, Jun 2, 2011 at 11:52 AM, Yves Parès wrote:

...

...

Learning Haskell will pay off much less than learning PHP, if your goal is to find a job.

Amen.

...

I cannot agree with this for practical reasons. I'm using Haskell for real world commercial applications, and I'm very productive with it.

I wish so much I could say that... Out of curiosity, what are you using Haskell for?

2011/6/2 Ertugrul Soeylemez

...

"Alberto G. Corona " wrote:

...

Haskell is an academic asset as well as a fun asset.

I cannot agree with this for practical reasons. I'm using Haskell for real world commercial applications, and I'm very productive with it.

There is however a variation of this statement, with which I could agree, namely: Learning Haskell will pay off much less than learning PHP, if your goal is to find a job. It takes a lot longer and there are a lot less companies in need of Haskell programmers.

Greets, Ertugrul

-- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/

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Michael Litchard writes:

I disagree. I'm by no means proficient in Haskell. And, I never bothered learning PHP. I will when I need to. PHP programmers are a dime a dozen.

..and since PHP programmers are a dime a dozen, any decent manager (who, after all, has an MBA and knows that employees¹ are expendable and interchangeable means of production) will select PHP as the technology for her next project. Gresham's law states roughly that bad money drives out good. I thus propose a corollary: bad languages drive out good.

It's been my experience that Haskell is a tool one may use to distinguish oneself from the hoi-poloi. This is important when you live in an area where the baker down the street has a CS degree.

Are you saying CS degrees are a dime a baker's dozen? -k ¹) With the sole exception of managers, of course. -- If I haven't seen further, it is by standing in the footprints of giants

I just wanted to echo this a bit. I'm a Ruby on Rails developer in my day job. While I still enjoy ruby, I was very proud that my studies of Haskell helped me identify a problem a week or so ago that would be much more difficult to solve in an imperative language and benefits from laziness. While the role of this tool will be limited compared to what I do day by day, I can finally say that I'm using Haskell at work. If anyone is curious, the project is essentially a service that determines the optimum order for a comparison shopping engine. On Thu, Jun 2, 2011 at 11:52 AM, Yves Parès wrote:

...

Learning Haskell will pay off much less than learning PHP, if your goal is to find a job.

Amen.

...

I cannot agree with this for practical reasons. I'm using Haskell for real world commercial applications, and I'm very productive with it.

I wish so much I could say that... Out of curiosity, what are you using Haskell for?

2011/6/2 Ertugrul Soeylemez

...

"Alberto G. Corona " wrote:

...

Haskell is an academic asset as well as a fun asset.

I cannot agree with this for practical reasons. I'm using Haskell for real world commercial applications, and I'm very productive with it.

There is however a variation of this statement, with which I could agree, namely: Learning Haskell will pay off much less than learning PHP, if your goal is to find a job. It takes a lot longer and there are a lot less companies in need of Haskell programmers.

Greets, Ertugrul

-- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/

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-- Michael Xavier http://www.michaelxavier.net

Yves Parès wrote:

From from what I see here, Haskell at work seems to target web development. I should try this soon...

That's one of the main use cases for Haskell in real world projects (in my opinion). However, I also use Haskell for network servers.

What is everyone using? Yesod?

Personally I use Yesod, but that's mainly a matter of taste. I think, the other big framework is Happstack. There is also a framework called Salvia. It comes with a very nice AJAX wiki/blog demo. You should check it out. The reason why I use Yesod is twofold: Firstly and mainly because I'm used to it. Secondly because I didn't like Happstack that much. I'm amazed by how you can get very productive with very little code, but that reasoning probably also holds for the other frameworks. One important note about Yesod, however: To really exploit it to its full power you should understand very well and be willing to use some of the Haskell extensions, most notably type families, quasiquoting and Template Haskell. Many people view this as a downside. Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/

For Scala, I think it's really due to the type of people that are attracted to the community. My impression is that more people are coming from Java programming than from academia.

Java developpers who whould be interested in doing things in a clean, expressive and manageable way? Maybe salvation is on sale today... (Btw, this *is** *meant to slight Java programmers ^^). |------------------------------| | Please do not feed the troll* | |-------------||---------------**| || || || || || * 2011/5/24 Sean Leather

Hi Gregory,

I had a similar experience on the scala-user list some time ago. I found most of the responses to my questions to be rather unproductive and superficial. I love the haskell-cafe community for their helpfulness and analytical approach.

I left scala-user not long afterward partly because of the aforementioned issues and partly because lurking there and reading threads did not provide any enlightenment on using Scala. With haskell-cafe, I can just read and (attempt to) absorb new knowledge. At least for me, the signal-to-noise ratio is higher on haskell-cafe than scala-user. (YMMV, of course.)

I'm not sure that the problem for the Scala community is growing pains. The Haskell community has been this way from the very beginning. In fact, the growing mix of people introduced to Haskell has lead to a great diversity of reactions: academic, hobbyist, getting-things-done, etc. For Scala, I think it's really due to the type of people that are attracted to the community. My impression is that more people are coming from Java programming than from academia. This probably has an effect on the community dynamics. (This is not meant to slight Java programmers. Rather, I think that the common perspective is more that of getting-things-done than deep-insight-into-the-problem.)

I also applaud the Haskell community for being very open and helpful. I would like to thank everyone who contributes to this environment. Group hug, indeed! ;)

Regards, Sean

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On Tue, 2011-05-24 at 15:37 +0100, Colin Adams wrote:

And I thought Hugs was dead. :-)

I think we have explanation for the friendliness of Haskell community - even the compiler hugs. Regards