Re: [Haskell-cafe] Efficient temporary file storage??

2012-01-24 Thread Gregory Crosswhite
On 1/24/12 5:51 PM, Vincent Hanquez wrote: On 01/24/2012 07:33 AM, Gregory Crosswhite wrote: On 1/24/12 9:43 AM, Felipe Almeida Lessa wrote: Use cereal [1], usually it's fast and easy enough. Out of curiosity, is binary no longer the recommended standard for such things? binary got only

Re: [Haskell-cafe] Efficient temporary file storage??

2012-01-23 Thread Gregory Crosswhite
On 1/24/12 9:43 AM, Felipe Almeida Lessa wrote: Use cereal [1], usually it's fast and easy enough. Out of curiosity, is binary no longer the recommended standard for such things? Cheers, Greg ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org

[Haskell-cafe] Why were unfailable patterns removed and fail added to Monad?

2012-01-19 Thread Gregory Crosswhite
Today I learned (tldr; TIL) that the fail in the Monad class was added as a hack to deal with the consequences of the decision to remove unfailable patterns from the language. I will attempt to describe the story as I have picked it up from reading around, but please feel free to correct me on

Re: [Haskell-cafe] Why were unfailable patterns removed and fail added to Monad?

2012-01-19 Thread Gregory Crosswhite
On 01/20/12 13:23, Edward Z. Yang wrote: In Haskell 1.4 g would not be in MonadZero because (a,b) is unfailable (it can't fail to match). But the Haskell 1.4 story is unattractive becuase a) we have to introduce the (new) concept of unfailable b) if you add

Re: [Haskell-cafe] Why were unfailable patterns removed and fail added to Monad?

2012-01-19 Thread Gregory Crosswhite
On 01/20/12 14:52, Michael Snoyman wrote: Essentially, I would want: SomeConstr args - someAction to be interpreted as: temp - someAction case temp of SomeConstr args - I completely agree; perhaps what we really want though is something more akin to a language extension --- say,

Re: [Haskell-cafe] How to catch all exceptions that could be caught?

2012-01-11 Thread Gregory Crosswhite
On 01/12/12 13:03, Magicloud Magiclouds wrote: Hi, With Prelude.catch, I could write catch () $ \_ - return Nothing. But with Control.Exception.catch, I must specify a type for the _. What should I do? Use SomeException for the type, as it is the base of the exception hierarchy. (Although

Re: [Haskell-cafe] How to catch all exceptions that could be caught?

2012-01-11 Thread Gregory Crosswhite
On 01/12/12 16:49, Ivan Lazar Miljenovic wrote: But it is usually recommended that you *don't* do this, as it even captures Ctrl-c invocations: Is that true in all threads, or just in the main thread? Cheers, Greg ___ Haskell-Cafe mailing list

Re: [Haskell-cafe] How to catch all exceptions that could be caught?

2012-01-11 Thread Gregory Crosswhite
On 01/12/12 17:07, Simon Hengel wrote: I think there are situation when it is justified to catch almost all exceptions. And people do that a lot, which often leads to ctrl-c not properly working (e.g. we had this in HUnit before 1.2.4.2). Indeed, and in fact this situation is a very natural

Re: [Haskell-cafe] How to catch all exceptions that could be caught?

2012-01-11 Thread Gregory Crosswhite
On 01/12/12 17:23, Gregory Crosswhite wrote: Indeed, and in fact this situation is a very natural occurrence whenever you are writing code that takes an arbitrary IO action, executes it, and then returns either the result or the exception that it threw. The code that I last used for this took

Re: [Haskell-cafe] How to catch all exceptions that could be caught?

2012-01-11 Thread Gregory Crosswhite
On 01/12/12 16:58, Magicloud Magiclouds wrote: Yes, that is a problem. But consider my PS in original mail, I have no idea what exception should I catch. Where could I get that information? In my experience, exceptions fall into three categories. First, when performing IO, some functions

Re: [Haskell-cafe] strict, lazy, non-strict, eager

2011-12-24 Thread Gregory Crosswhite
On Dec 24, 2011, at 6:22 PM, Tony Morris wrote: Wait what? I find it intriguing, helpful, provocative and potentially helpful toward the common goal of helping others. I am interested in further commentary. I'm not scared and you shouldn't be either. Asking honest questions is

Re: [Haskell-cafe] strict, lazy, non-strict, eager

2011-12-24 Thread Gregory Crosswhite
On Dec 24, 2011, at 6:47 PM, Murray Campbell wrote: It's too late to avoid success at all costs but please don't banish our precious pedantry! Scare on! Please don't misunderstand, I have absolutely no problems at all with people arguing voraciously and pedantically over ideas, as long as

Re: [Haskell-cafe] Interruptible threads with IO loops

2011-12-21 Thread Gregory Crosswhite
On Dec 21, 2011, at 6:52 PM, Fedor Gogolev wrote: Hello. I'm trying to get some threads that I can stop and get last values that was computed (and that values are IO values, in fact). Here is my first approach: [...] tick :: Int - IO Int tick v = return $ v + 1 [...] The problem is that

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-21 Thread Gregory Crosswhite
On Dec 20, 2011, at 11:18 PM, Heinrich Apfelmus wrote: Tillmann Rendel wrote: Hi, Robert Clausecker wrote: Image you would create your own language with a paradigm similar to Haskell or have to chance to change Haskell without the need to keep any compatibility. What stuff would you add to

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-21 Thread Gregory Crosswhite
On Dec 22, 2011, at 12:25 PM, Alexander Solla wrote: It is not limiting to make distinctions that capture real differences. An overly broad generalization limits what can be proved. Can we prove that every vehicle with wheels has a motor? Of course not -- bicycles exist. Can we prove

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-21 Thread Gregory Crosswhite
On Dec 22, 2011, at 12:40 PM, Alexander Solla wrote: fst _|_ = _|_ This expression is basically non-sense. This is only nonsense because you refuse to accept that there are valid formalisms other than your own that contain _|_ as a perfectly valid entity. :-) Should we accept

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 20, 2011, at 8:05 PM, Tillmann Rendel wrote: Hi, Robert Clausecker wrote: Image you would create your own language with a paradigm similar to Haskell or have to chance to change Haskell without the need to keep any compatibility. What stuff would you add to your language, what

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 20, 2011, at 8:30 PM, Jesse Schalken wrote: On Tue, Dec 20, 2011 at 8:46 PM, Ben Lippmeier b...@ouroborus.net wrote: On 20/12/2011, at 6:06 PM, Roman Cheplyaka wrote: In denotational semantics, every well-formed term in the language must have a value. So, what is a value of

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 20, 2011, at 8:40 PM, Jesse Schalken wrote: If you think a value might not reduce, return an error in an error monad. Okay, I'm completely convinced! Now all that we have to do is to solve the halting problem to make your solution work... :-) Cheers,

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 20, 2011, at 8:38 PM, Ben Lippmeier wrote: Some would say that non-termination is a computational effect, and I can argue either way depending on the day of the week. *shrug* I figure that whether you call _|_ a value is like whether you accept the Axiom of Choice: it is a

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 20, 2011, at 9:18 PM, Jesse Schalken wrote: Why do you have to solve the halting problem? You have to solve the halting problem if you want to replace every place where _|_ could occur with an Error monad (or something similar), because _|_ includes occasions when functions will never

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 20, 2011, at 11:21 PM, Jesse Schalken wrote: On Tue, Dec 20, 2011 at 10:43 PM, Gregory Crosswhite gcrosswh...@gmail.com wrote: On Dec 20, 2011, at 9:18 PM, Jesse Schalken wrote: Why do you have to solve the halting problem? You have to solve the halting problem if you want

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 21, 2011, at 2:14 PM, scooter@gmail.com wrote: I'd suggest, in addition to the symbols, renaming some of the fundamental types and concepts, like Monad. I would violently agree that Monad is the correct term, but try to communicate with a commodity software developer sometime

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 21, 2011, at 2:24 PM, Alexander Solla wrote: I would rather have an incomplete semantic, and have all the incomplete parts collapsed into something we call bottom. We can then be smart and stay within a total fragment of the language (where bottom is guaranteed to not occur).

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-20 Thread Gregory Crosswhite
On Dec 21, 2011, at 8:52 AM, Jesse Schalken wrote: I don't have experience with proof assistants, but maybe my answer to this thread can be summed up as giving Haskell that kind of capability. ;) Okay, then suffice it to say that most of what you said *is* implemented in real languages

Re: [Haskell-cafe] If you'd design a Haskell-like language, what would you do different?

2011-12-19 Thread Gregory Crosswhite
On Dec 20, 2011, at 5:20 AM, Robert Clausecker wrote: What stuff would you add to your language Gratuitous use of parentheses. Cheers, Greg___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] [Alternative] summary of my understanding so far

2011-12-18 Thread Gregory Crosswhite
On Dec 19, 2011, at 12:39 PM, Brandon Allbery wrote: On Sun, Dec 18, 2011 at 20:42, Richard O'Keefe o...@cs.otago.ac.nz wrote: No. Not by a country mile. It's better than non-existent. It's better than misleading. But it's not even on the same *continent* as adequate. +1 So what do

Re: [Haskell-cafe] [Alternative] summary of my understanding so far

2011-12-18 Thread Gregory Crosswhite
On Dec 19, 2011, at 1:03 PM, Alexander Solla wrote: The incidental comment is significantly more clear than an English description. That is only true for someone who has already seen a sentence like that one before and so can immediately pick up what it is getting at. :-) In particular,

Re: [Haskell-cafe] [Alternative] summary of my understanding so far

2011-12-18 Thread Gregory Crosswhite
On Dec 19, 2011, at 1:01 PM, Richard O'Keefe wrote: On 19/12/2011, at 3:44 PM, Gregory Crosswhite wrote: So what do you all think about my own suggestion for the documentation? It is an improvement. Documentation for a library module needs to start by telling people what

Re: [Haskell-cafe] [Alternative] summary of my understanding so far

2011-12-18 Thread Gregory Crosswhite
On Dec 19, 2011, at 1:01 PM, Richard O'Keefe wrote: Documentation for a library module needs to start by telling people what it is for. For a particular function, someone needs to know very quickly is this what I am looking for? is this the kind of thing I _should_ have been looking for?

Re: [Haskell-cafe] [Alternative] summary of my understanding so far

2011-12-18 Thread Gregory Crosswhite
On Dec 19, 2011, at 3:49 PM, Richard O'Keefe wrote: On 19/12/2011, at 5:46 PM, Gregory Crosswhite wrote: [improved Monoid documentation] Thank you. :-) I would go so far as to point out that mappend is a generalisation of Data.List.sum, Data.List.product, Data.List.and, and Data.List.or

Re: [Haskell-cafe] [Alternative] summary of my understanding so far

2011-12-18 Thread Gregory Crosswhite
On Dec 19, 2011, at 4:45 PM, Gregory Crosswhite wrote: First, there needs to be lots of [STRUCTURE] that makes it easy for people to skim through and pick out the specific information that they want to find out about [...] Grr! I have no idea why that word got dropped out, since

Re: [Haskell-cafe] [Alternative] summary of my understanding so far

2011-12-16 Thread Gregory Crosswhite
On Dec 17, 2011, at 12:35 PM, Matthew Farkas-Dyck wrote: (1) If we do (4), then the documentation ought to be adequate as-is. I see your point that if we do (4) then some and many are no longer problematic for Maybe and [], and thus we don't need warnings for those types. However,

Re: [Haskell-cafe] Alternative versus Monoid

2011-12-16 Thread Gregory Crosswhite
On Dec 17, 2011, at 1:26 AM, Yves Parès wrote: 1) What about the First type? Do we {-# DEPRECATE #-} it? Personnaly, I'm in favor of following the same logic than Int: Int itself is not a monoid. You have to be specific: it's either Sum or Mult. It should be the same for Maybe: we remove

Re: [Haskell-cafe] Alternative versus Monoid

2011-12-16 Thread Gregory Crosswhite
On Dec 17, 2011, at 1:26 AM, Yves Parès wrote: 1) What about the First type? Do we {-# DEPRECATE #-} it? Personnaly, I'm in favor of following the same logic than Int: Int itself is not a monoid. You have to be specific: it's either Sum or Mult. It should be the same for Maybe: we remove

Re: [Haskell-cafe] Alternative versus Monoid

2011-12-16 Thread Gregory Crosswhite
On Dec 17, 2011, at 12:51 PM, Matthew Farkas-Dyck wrote: By my reason, the instance (Monoid a = Monoid (Maybe a)) is appropriate, since we have another class for inner-type-agnostic choice -- Alternative! (and MonadPlus, but that's essentially the same, and would be if (Functor m =

Re: [Haskell-cafe] Alternative versus Monoid

2011-12-16 Thread Gregory Crosswhite
On Dec 17, 2011, at 2:57 PM, Gregory Crosswhite wrote: +1 for this idea, because it follows the principle of least surprise. Sorry about the double-post! I was foolish enough not only to use unsafePerformIO to send my e-mail, but to forgot to mark the sending routine with NOINLINE pragma

Re: [Haskell-cafe] Type checker for haskell-src-exts (was: Typechecking Using GHC API)

2011-12-16 Thread Gregory Crosswhite
On Dec 17, 2011, at 9:58 AM, Thomas Schilling wrote: Wll... I've gotten a little bit of a different perspective on this since working at a company with very high code quality standards (at least for new code). There is practically no observable code review happening. I'm sure Dimitrios

[Haskell-cafe] [Alternative] summary of my understanding so far

2011-12-15 Thread Gregory Crosswhite
Hey everyone! First of all, it sounds like we all agree that the documentation for Alternative needs to be improved; that alone would clear a lot of the confusion up. I think that a fairly convincing case has also been made that removing many/some from the typeclass doesn't help too much

Re: [Haskell-cafe] [Alternative] change some/many semantics

2011-12-15 Thread Gregory Crosswhite
On Dec 15, 2011, at 5:40 PM, Antoine Latter wrote: I said 'combinators', not 'instances'. Oh! Okay, that was my bad then. A lot of popular parsers combinators can be written exclusively from (|) and empty, but make little sense for List and Maybe, and may not even function properly. The

Re: [Haskell-cafe] [Alternative] change some/many semantics

2011-12-15 Thread Gregory Crosswhite
On Dec 15, 2011, at 6:19 PM, Gregory Crosswhite wrote: After all, we already have the Monad typeclass which gives them essentially the same functionality. Make that the *Monoid* typeclass. :-) Cheers, Greg___ Haskell-Cafe mailing list Haskell

[Haskell-cafe] Alternative versus Monoid

2011-12-15 Thread Gregory Crosswhite
Hey everyone, First, thank you all for this great discussion! I unfortunately have been home due to health concerns which gets really boring after a while, so being able to participate in such a fun intellectual exercise like has really been making my day. :-D Sorry that this has resulted

Re: [Haskell-cafe] [Alternative] change some/many semantics

2011-12-15 Thread Gregory Crosswhite
On Dec 15, 2011, at 9:31 PM, malcolm.wallace wrote: I do not regard that as a change in their semantics - it is perfectly allowed already Indeed, the instances of some/many that I write are already lazily-unfolding, wherever possible. It all depends simply on whether your instance of

Re: [Haskell-cafe] [Alternative] some/many narrative

2011-12-15 Thread Gregory Crosswhite
On Dec 16, 2011, at 3:34 AM, Bryan O'Sullivan wrote: This is both confusing and incorrect. It's entirely possible for an action in the Maybe type to fail. Okay, so inserting the phrases that either fail eventually or and that succeed forever if they do not immediately fail so that that the

Re: [Haskell-cafe] Alternative versus Monoid

2011-12-15 Thread Gregory Crosswhite
On Dec 16, 2011, at 3:59 AM, Carl Howells wrote: Monoid and Alternative are not the same. There is a very important difference between them: class Alternative f where (|) :: f a - f a - f a ... class Monoid a where mappend :: a - a - a ... The equivalent to

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-14 Thread Gregory Crosswhite
On Dec 14, 2011, at 4:40 PM, Ivan Lazar Miljenovic wrote: [...] Apart from some basic combinators in Control.Monad or the definitions of monad transformers, how much of what you write in do-blocks is applicable to some generic Monad instance as opposed to a specific Monad? Well, if my

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-14 Thread Gregory Crosswhite
On Dec 15, 2011, at 3:37 AM, Bryan O'Sullivan wrote: But that's precisely what the Alternative class is already for! If you are writing an Alternative instance at all, then you are asserting that it must be possible and reasonable to replicate the existing behaviour of some and many.

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-14 Thread Gregory Crosswhite
On Dec 15, 2011, at 12:03 PM, Ross Paterson wrote: The current definition says that some and many should be the least solutions of the equations some v = (:) $ v * many v many v = some v | pure [] We could relax that to just requiring that they satisfy these equations (which I

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-14 Thread Gregory Crosswhite
On Dec 15, 2011, at 12:36 PM, Antoine Latter wrote: Although I'm still not sure why I would be using these operations in maybe or list. You probably wouldn't use these operations directly on Maybe or List, but the whole point is that when you are using a typeclass you have cannot assume that

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-14 Thread Gregory Crosswhite
On Dec 15, 2011, at 12:52 PM, Brandon Allbery wrote: These statements are not mutually logically consistent, and leave me wondering if Applicative and/or Alternative have been fully thought out. Oh, that particular question is *super*-easy to answer: based on what I've been reading, they

[Haskell-cafe] [Alternative] some/many narrative

2011-12-14 Thread Gregory Crosswhite
Okay, so how about the following as a user narrative for some and many? many v = repeatedly execute the action v and save each obtained result until v fails; at that point, *succeed* and return a list with all of the results that had been collected some v = like many v, but if

[Haskell-cafe] [Alternative] change some/many semantics

2011-12-14 Thread Gregory Crosswhite
Hey everyone, This is even more out there than my previous posts, but the following just occurred to me: is it absolutely necessary that some/many have produced the entire list of results before returning? Couldn't we change their semantics so that the list of results is computed and/or

Re: [Haskell-cafe] [Alternative] change some/many semantics

2011-12-14 Thread Gregory Crosswhite
On Dec 15, 2011, at 2:13 PM, Antoine Latter wrote: Isn't this what Ross previously suggested? I think his suggested instance methods for Maybe return the elements of the lists incrementally. Yes and no. Yes, his excellent suggestion is one of my favorite ideas for what we should do with

Re: [Haskell-cafe] [Alternative] change some/many semantics

2011-12-14 Thread Gregory Crosswhite
On Dec 15, 2011, at 3:36 PM, Antoine Latter wrote: That's the interesting thing about type-classes like Alternative and Functor - they mean very little, and are used in widely varying contexts. So... your point is that in the Haskell community we don't tend to care about whether our types,

Re: [Haskell-cafe] [Alternative] some/many narrative

2011-12-14 Thread Gregory Crosswhite
On Dec 15, 2011, at 4:29 PM, Chris Wong wrote: Okay, so how about the following as a user narrative for some and many? ... I was in the middle of writing my own version of Applicative when I stumbled on this intense debate. Here's what I wrote for the documentation: class

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-13 Thread Gregory Crosswhite
On Dec 13, 2011, at 3:06 AM, Bryan O'Sullivan wrote: There is absolutely no implication of consuming anything in the definitions of many or some. This is how they happen to behave when used in the context of some parsing libraries, but that's all. If many or some always go into an

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-13 Thread Gregory Crosswhite
On Dec 13, 2011, at 5:09 AM, Bryan O'Sullivan wrote: Correct. And your example of some (Just 1) inflooping was not a counterargument, but rather an illustration that perhaps some people (and I'm not trying to imply you here, don't worry) don't understand what some and many are supposed to

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-13 Thread Gregory Crosswhite
On Dec 13, 2011, at 5:09 AM, Bryan O'Sullivan wrote: Correct. And your example of some (Just 1) inflooping was not a counterargument, but rather an illustration that perhaps some people (and I'm not trying to imply you here, don't worry) don't understand what some and many are supposed to

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-13 Thread Gregory Crosswhite
On Dec 14, 2011, at 8:38 AM, Thomas Schilling wrote: On 12 December 2011 22:39, Antoine Latter aslat...@gmail.com wrote: But now they look as if they are of equal importance with the other class methods, which is not really true. Maybe, but something like this is best fixed by improving

Re: [Haskell-cafe] Splitting off many/some from Alternative

2011-12-13 Thread Gregory Crosswhite
On Dec 13, 2011, at 3:32 AM, Bryan O'Sullivan wrote: Don't be silly. The purpose of some and many is to be used with combinators that are expected to fail sometimes. If you use them with combinators that always succeed, of course you're going to get an infinite loop. Yes, but how can

[Haskell-cafe] Linear types using kinds?

2011-12-12 Thread Gregory Crosswhite
Hey everyone! So, I was on LtU reading about F* http://lambda-the-ultimate.org/node/4318 and an idea just occurred to me which *must* have occurred to someone smarter than me, so I would love your feedback on the following question: Could Haskell be extended to support linear/affine

[Haskell-cafe] Splitting off many/some from Alternative

2011-12-11 Thread Gregory Crosswhite
Hey everyone, I am sure that it is too late to do more than idly speculate about this, but could we split the some/many methods out from Alternative? They simply don't make sense except in a subset of possible Alternatives --- in most cases they just result in an infinite loop. That is to

[Haskell-cafe] Built-in LLVM exception handling

2011-11-28 Thread Gregory Crosswhite
Purely out of curiosity, would it be more efficient for GHC to use the new built-in exception handling instructions in LLVM? http://blog.llvm.org/2011/11/llvm-30-exception-handling-redesign.html Cheers, Greg___ Haskell-Cafe mailing list

[Haskell-cafe] Hackage feature request: E-mail author when a package breaks

2011-10-31 Thread Gregory Crosswhite
Hey everyone, I have uploaded a number of small packages to Hackage that I no longer actively use so that I don't find out immediately when a new version of GHC has broken them. Since Hackage is going to the trouble of finding out when a package no longer builds anyway, could it have a

[Haskell-cafe] MonadPlus versus Alternative

2011-10-29 Thread Gregory Crosswhite
Hey everyone, What is the difference between MonadPlus and Alternative? In my mind, it would make sense for the difference to be that the former provides and semantics (i.e., x `mplus` y means do both x and y) whereas the latter provides or semantics (i.e., x | y means do x or y but not

Re: [Haskell-cafe] The Typeable class is changing

2011-07-11 Thread Gregory Crosswhite
On 7/11/11 11:18 AM, Yitzchak Gale wrote: The standard way to create a Typeable instance is just to derive it. If you do that, you will not be affected by this change. This is only the standard way if one is willing to sacrifice Haskell98 or Haskell2010 compatibility by using the

Re: [Haskell-cafe] Lazy Evaluation in Monads

2011-05-31 Thread Gregory Crosswhite
On 5/31/11 12:49 PM, Scott Lawrence wrote: I was under the impression that operations performed in monads (in this case, the IO monad) were lazy. Whether they are lazy or not depends entirely on the definition of the monad. For example, if you look up the ST and State monads you will find

Re: [Haskell-cafe] Erlang's module discussion

2011-05-30 Thread Gregory Crosswhite
On 5/28/11 10:11 AM, Alex Rozenshteyn wrote: Since no-one has yet mentioned it, and I think it might be relevant, http://types.bu.edu/seminar-modularity/first-class-modules-for-haskell.pdf I haven't read it with any degree of understanding, but I don't think it's tractable to remove modules

Re: [Haskell-cafe] [Maybe Int] sans Nothings

2011-05-23 Thread Gregory Crosswhite
On 5/23/11 9:20 AM, michael rice wrote: What's the best way to end up with a list composed of only the Just values, no Nothings? Try catMaybes in Data.Maybe. Cheers, Greg ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org

Re: [Haskell-cafe] [Maybe Int] sans Nothings

2011-05-23 Thread Gregory Crosswhite
on first result. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe On 5/23/11 9:25 AM, Gregory Crosswhite wrote: On 5/23/11 9:20 AM, michael rice wrote: What's the best way to end up

Re: [Haskell-cafe] [Maybe Int] sans Nothings

2011-05-23 Thread Gregory Crosswhite
On 05/23/2011 12:08 PM, Brent Yorgey wrote: Just a minor quibble: note that filter (not . isNothing) is slightly preferable since it does not introduce a frivolous equality constraint on the type wrapped by the Maybe. Or even better, filter isJust :-) Cheers, Greg

[Haskell-cafe] *GROUP HUG*

2011-05-23 Thread 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

Re: [Haskell-cafe] Status of Haskell + Mac + GUIs graphics

2011-05-20 Thread Gregory Crosswhite
On 5/20/11 8:35 AM, Jeremy O'Donoghue wrote: I would like to suggest, quite seriously, that the Haskell community try to come to a consensus about supporting a single Haskell GUI, with a view to distribution in the HP. Obviously my vote is for wxHaskell, but I'm quite prepared to loose the

Re: [Haskell-cafe] Using cmake with haskell

2011-05-14 Thread Gregory Crosswhite
On 5/14/11 1:25 PM, Maciej Marcin Piechotka wrote: (to mention one which is often neglected - parallel build). While I do appreciate you stepping in to defend autotools (if for no other reason then because someone has to so that the discussion is balanced :-) ), I think that you are wrong to

Re: [Haskell-cafe] Using cmake with haskell

2011-05-14 Thread Gregory Crosswhite
. I use it in a mixed Haskell, C++, Scala and Python build. If there is interest I could conceivably clean up the ghc waf tool and release it. On Sat, May 14, 2011 at 5:32 PM, Gregory Crosswhite gcr...@phys.washington.edu mailto:gcr...@phys.washington.edu wrote: On 5/14/11 1:25 PM, Maciej

Re: [Haskell-cafe] Using cmake with haskell

2011-05-11 Thread Gregory Crosswhite
On 5/11/11 3:11 PM, Bryan O'Sullivan wrote: It's a fairly terrible piece of software. My experience is that it is the only cross-platform build system I have used to date that hasn't made my eyes bleed, though I only use it for C/C++/Fortran. I suppose that counts as a personal testimonial in

Re: [Haskell-cafe] Proving correctness

2011-02-14 Thread Gregory Crosswhite
On 2/11/11 1:25 PM, Luke Palmer wrote: I would like to see a language that allowed optional verification, but that is a hard balance to make because of the interaction of non-termination and the evaluation that needs to happen when verifying a proof. I believe that ATS (short for Advanced Type

Re: [Haskell-cafe] Type System vs Test Driven Development

2011-01-12 Thread Gregory Crosswhite
On 1/12/11 5:05 AM, Ketil Malde wrote: Of course, ideally you should design your types so that all possible values are meaningful:-) Sadly we cannot all program in Agda. :-) Cheers, Greg ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org

Re: [Haskell-cafe] [darcs-users] Darcs failure

2010-12-24 Thread Gregory Crosswhite
On 12/24/10 4:08 PM, Andrew Coppin wrote: Gotta love the way that this is THE MOST COMMON USE CASE for kill, and yet kill itself doesn't support doing this. The problem with killing processes by name is that names aren't unique, so you might unintentionally end up killing other processes that

Re: [Haskell-cafe] IO, sequence, lazyness, takeWhile

2010-12-13 Thread Gregory Crosswhite
Take a look at the monad-loops package. Cheers, Greg On 12/13/2010 06:15 AM, Jacek Generowicz wrote: -- Is it possible to rewrite code written in this style untilQuit = do text - getLine report text if text == quit then return () else untilQuit -- in a style using higher

Re: [Haskell-cafe] Wondering if this could be done.

2010-11-21 Thread Gregory Crosswhite
On 11/21/10 10:48 PM, Magicloud Magiclouds wrote: Hi, For example, I have a data A defined. Then I want to add (+) and (-) operators to it, as a sugar (compared to addA/minusA). But * or other stuff defined in class Num is meanless to A. So I just do: (+) :: A - A - A (+) a b = A (elem1

[Haskell-cafe] Impredicative Types

2010-11-19 Thread Gregory Crosswhite
Hey everyone! I haven't had a chance to try out GHC 7 myself, but I saw in the documentation that Impredicative Types are still supported. Is this true? I thought that they were on their way out because they overcomplicated type checking; has this plan been changed? Cheers, Greg

Re: [Haskell-cafe] Impredicative Types

2010-11-19 Thread Gregory Crosswhite
motivate me to do the remaining work! Thanks Simon | -Original Message- | From: haskell-cafe-boun...@haskell.org [mailto:haskell-cafe-boun...@haskell.org] | On Behalf Of Gregory Crosswhite | Sent: 19 November 2010 19:23 | To: Haskell Cafe | Subject: [Haskell-cafe] Impredicative Types

Re: [Haskell-cafe] Impredicative Types

2010-11-19 Thread Gregory Crosswhite
On 11/19/10 12:22 PM, Andrew Coppin wrote: Use the Force I tried, but I'm not yet strong enough in the Force to read citations with my eyes closed. :-( (PS: Thanks for pointing me to the paper, Simon!) Cheers, Greg ___ Haskell-Cafe mailing list

Re: [Haskell-cafe] Serialization of (a - b) and IO a

2010-11-11 Thread Gregory Crosswhite
On 11/11/10 12:07 PM, C. McCann wrote: To retain sanity, either types that can be serialized must be marked explicitly (perhaps in the context, similar to having a Data.Typeable constraint) to indicate potential non-parametric shenanigans You mean, like Data.Binary? Cheers, Greg

Re: [Haskell-cafe] How to put a string into Data.Binary.Put

2010-11-06 Thread Gregory Crosswhite
On 11/6/10 6:38 AM, C K Kashyap wrote: Thanks a lot Gregory and Daniel, I think I'll go with the mapM_ (putWord8 . fromIntegral . ord) approach. If your string has any chance of containing Unicode characters then you will want to use the encode function in the module

Re: [Haskell-cafe] Is Curry alive?

2010-11-04 Thread Gregory Crosswhite
On 11/02/2010 08:37 PM, wren ng thornton wrote: Indeed. If your program requires unification or constraint solving then logic programming or constraint programming[1] is the way to go. Would you be kind enough to give me or point me towards a good example of such a case? I've been trying to

Re: [Haskell-cafe] Re: Haskell is a scripting language inspired by Python.

2010-11-04 Thread Gregory Crosswhite
On 11/04/2010 03:30 PM, Lennart Augustsson wrote: KRC, Miranda, and LML all predate Haskell and have list comprehensions. Just because those languages predate Haskell and have list comprehensions doesn't mean that they still couldn't have gotten the idea from Haskel!. After all, I fully

Re: [Haskell-cafe] Is Curry alive?

2010-11-04 Thread Gregory Crosswhite
On 11/04/2010 03:06 PM, Dan Doel wrote: Implementing type inference can be very easy in a logic language, because most of the work in a non-logic language is implementing unification: http://muaddibspace.blogspot.com/2008/01/type-inference-for-simply-typed- lambda.html 3 lines of Prolog to

Re: [Haskell-cafe] What is simplest extension language to implement?

2010-11-02 Thread Gregory Crosswhite
I haven't ever used it myself, but I've heard good things about Lua, which was designed to be an embedded scripting language for applications: http://www.lua.org/ If you believe the Programming Language Shootout (http://shootout.alioth.debian.org/) it is pretty fast for a dynamic

Re: [Haskell-cafe] Is Curry alive?

2010-11-02 Thread Gregory Crosswhite
On 11/2/10 8:37 PM, wren ng thornton wrote: Though I would suggest you look at the LogicT library instead of using actual lists... Also, you may be interested in reading the LogicT paper[2] or this paper[3] about search combinators in Haskell. Both offer a number of optimizations you should be

[Haskell-cafe] Is Curry alive?

2010-11-01 Thread Gregory Crosswhite
Hey everyone, This is a little off-topic, but I just ran into a problem which might benefit from being attacked by a logic language, so I've been looking for a good one to try out --- and hopefully one that has a very efficient implementation since I want to iterate through billions and

Re: [Haskell-cafe] Is Curry alive?

2010-11-01 Thread Gregory Crosswhite
On 11/01/2010 06:19 PM, Richard O'Keefe wrote: On 2/11/2010, at 1:27 PM, Gregory Crosswhite wrote: Hey everyone, This is a little off-topic, but I just ran into a problem which might benefit from being attacked by a logic language, Why not describe the problem? My goal

Re: [Haskell-cafe] who's in charge?

2010-10-29 Thread Gregory Crosswhite
Also, this is a complete aside but what the heck. :-) Has anyone else been driven crazy by the way that Java code and libraries are documented? It seems like whenever I try to figure out how to use a piece of Java code, the functionality is spread out over a huge collection of classes and

Re: [Haskell-cafe] Monads and Functions sequence and sequence_

2010-10-29 Thread Gregory Crosswhite
The expression sequence [a,b,c,...] is roughly equivalent to do r_a - a r_b - b r_c - c ... return [r_a,r_b,r_c,...] The expression sequence_ [a,b,c,...] is roughly equivalent to do a b c ...

Re: [Haskell-cafe] Edit Hackage

2010-10-28 Thread Gregory Crosswhite
On 10/28/10 12:34 PM, Andrew Coppin wrote: More specifically, I copied the Cabal description from another package and then updated all the fields. Except that I forgot to update one. And now I have a package which I've erroneously placed in completely the wrong category. I am glad to hear that

Re: [Haskell-cafe] who's in charge?

2010-10-28 Thread Gregory Crosswhite
Or if you want to keep the advantages of a powerful type system, you can use Scala. Cheers, Greg On 10/28/10 9:53 PM, aditya siram wrote: I understand your frustration at not having free tested libs ready-to-go, Java/any-other-mainstream-language programmers tend to expect this and usually

Re: [Haskell-cafe] concurrency vs. I/O in GHC

2010-10-23 Thread Gregory Crosswhite
On 10/23/10 7:54 AM, John Lato wrote: On Fri, Oct 22, 2010 at 6:16 PM, Bulat Ziganshin bulat.zigans...@gmail.com mailto:bulat.zigans...@gmail.com wrote: Hello John, Monday, October 18, 2010, 8:15:42 PM, you wrote: If anyone is listening, I would very much like for there to be a

Re: [Haskell-cafe] concurrency vs. I/O in GHC

2010-10-23 Thread Gregory Crosswhite
On 10/23/10 12:57 PM, Claude Heiland-Allen wrote: On 23/10/10 17:42, Gregory Crosswhite wrote: On 10/23/10 7:54 AM, John Lato wrote: On Fri, Oct 22, 2010 at 6:16 PM, Bulat Ziganshin This doesn't work, which was why the OP asked in the first place. When a thread calls an unsafe foreign

Re: [Haskell-cafe] Template Haskell: onward and upward

2010-10-18 Thread Gregory Crosswhite
Since you are proposing creating an abstract type TExp that can't be created manually in contrast to Exp, I have a question that might simply be a reflection of ignorance on my part on how TH works now. As far as I can tell by looking through the documentation, when I want to create an

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