Re: [Haskell-cafe] MonadPlus m = Maybe a - m a
On Sat, Jul 28, 2012 at 8:00 AM, Thiago Negri evoh...@gmail.com wrote: I'm solving this exercise: http://www.haskell.org/haskellwiki/All_About_Monads#Exercise_4:_Using_the_Monad_class_constraint I'm missing a function to transform a Maybe a into a MonadPlus m = m a. I did search on Hoogle with no luck. There is no standard definition for the g function I'm defining? g :: (MonadPlus m) = Maybe a - m a g Nothing = mzero g (Just a) = return a I doubt there is a standard named function for this, since conversions between monads are typically not unique and there are lots and lots of pairs of monads you can convert between. You can define g in terms of Data.Maybe.maybe as: g = maybe mzero return ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus versus Alternative
On Sun, Oct 30, 2011 at 04:02, Gregory Crosswhite wrote: So is there any difference between the interpretation of MonadPlus and Alternative, or is the only difference between them that the former applies to Monad whereas the latter applies to Applicative? Somewhat OT, but this led me to playing with ConstraintKinds: https://github.com/spl/sandbox/blob/master/ConstraintKindsAlternativeMonadPlus.lhs Regards, Sean ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus versus Alternative
On 10/29/11 11:02 PM, Gregory Crosswhite wrote: 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 both). However, when I look at the instances defined for List I see that it is exactly the same as MonadPlus. As other's've mentioned, they both have or semantics and it's just an artifact of the Monad/Applicative split. However, an additional note. For lists or sets, the mplus/(|) functions could be interpreted as both and and or semantics, depending on what you think lists are. If you think of them as a collection of multiple answers, then concatenating/unioning is colloquially regarded as saying I have xs and ys. However, if you think of them as giving a non-deterministic answer, then the concatenation/union should be regarded as saying you can chose the xs or the ys, which is closer to the logical interpretation of union as disjunction. I guess my point is that the notion of and isn't especially well-defined. At the very least there are three different notions of and. We have the andThen notion which corresponds to monadic bind, probabilistic conjunction, and Sigma types. We have the andAlso notion which corresponds to unions conceived of as nondeterminisms, also covers the linear conjunction which only lets you take one of the projections, and is the one involved with the idea of anding two functions with (+++). And we have the bothAnd notion which corresponds to Cartesian products, logical conjunction, the linear conjunction which lets you take both projections, and the notion of anding two functions with (***). -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus versus Alternative
MonadPlus is `or` semantics, as is Alternative. It does, indeed, reflect the Applicative/Monad difference. On Sat, Oct 29, 2011 at 8:02 PM, Gregory Crosswhite gcrosswh...@gmail.comwrote: 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 both). However, when I look at the instances defined for List I see that it is exactly the same as MonadPlus. So is there any difference between the interpretation of MonadPlus and Alternative, or is the only difference between them that the former applies to Monad whereas the latter applies to Applicative? Also, along similar lines, why does MonadPlus exist when it is essentially just a special case of Monoid? (That is, any MonadPlus instance could be equivalently cast as a Monoid instance.) Thanks! Greg ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus or Alternative or ...?
On Sat, May 1, 2010 at 7:11 PM, Sean Leather leat...@cs.uu.nl wrote: I want to generalize a set of functions from lists to some functor type. I require the following three operation types. f a a - f a f a - f a - f a Since f is a functor, FunctorPlus and Pointed together get you exactly the subset of functionality that you want. Whether or not category-extras can be considered a light weight dependency on the other hand is another thing entirely. ;) -Edward Kmett ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus or Alternative or ...?
On Sun, May 2, 2010 at 4:23 AM, Sebastian Fischer s...@informatik.uni-kiel.de wrote: Ideally, every MonadPlus instance would also be an Alternative instance and every Alternative instance would be an instance of Monoid. You may find it unfortunate that there are so many operations for the same thing but until the (Applicative/Monad) class hierarchy is refactored, we have to live with it. Sadly there is at least one MonadPlus/Alternative and Monoid instance that differs: Maybe The Monoid instance for Maybe is the lifting of a semigroup into a monoid by adding an identity element, but unfortunately, it does so rather poorly as there is no semigroup class that it can assume for its argument, and so it lifts a monoid into a monoid, while avoiding the use of the underlying definition for mempty. =/ So there is no path forward that doesn't change the meaning of existing programs that makes the Alternative and Monoid instances agree on all Applicatives. -Edward Kmett ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus or Alternative or ...?
On May 2, 2010, at 1:11 AM, Sean Leather wrote: I want to generalize a set of functions from lists to some functor type. [...] Should I choose MonadPlus and use these? [...] Or should I choose Alternative and use these? [...] There are some types that can be an instance of Alternative but not of MonadPlus (because they are not a monad but an applicative functor). Hence, if you choose Alternative, then your functions are more generally applicable. In practice, there may be instances of MonadPlus for wich their authors chose not to provide an Alternative instance and your functions then could not be applied to those types. But every MonadPlus instance `m` can be made an Alternative instance by declaring instance Functor m where fmap = liftM instance Applicative m where pure = return (*) = ap instance Alternative m where empty = mzero (|) = mplus The laws required by MonadPlus imply the laws required by theses instances. Or should I make my own class? Then, there obviously won't be any instances for existing types other than your own (which might be a good or bad thing). You may want to do this, if you don't want to require either (=) or (*), which may not be supported for reasonable instances of your own class. Or is there another option? If you have functions that do not need return/pure you can also use a Monoid constraint on those functions and replace empty/mzero with mempty and |/mplus with mappend. Again, those functions share the same laws. Ideally, every MonadPlus instance would also be an Alternative instance and every Alternative instance would be an instance of Monoid. You may find it unfortunate that there are so many operations for the same thing but until the (Applicative/Monad) class hierarchy is refactored, we have to live with it. Sebastian -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus or Alternative or ...?
On May 2, 2010, at 11:10 AM, Sean Leather wrote: Or should I make my own class? Then, there obviously won't be any instances for existing types other than your own (which might be a good or bad thing). You may want to do this, if you don't want to require either (=) or (*), which may not be supported for reasonable instances of your own class. I don't really want to do this option, because it increases the understanding overhead needlessly, I think. Everything else that is provided by Applicative/Monad doesn't matter. I require only the three operations above and do not disallow extra operations. By not making your own class, you prohibit types that do not support * (or =). That's fine, but an additional burden to instance writers. By not listing extra operations in your own class you would not disallow them. You require them by not making your own class without them. But still, your wish to reuse existing classes may be a fine reason to impose an additional burden. Sebastian -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus or Alternative or ...?
On Sun, May 2, 2010 at 12:07, Sebastian Fischer wrote: On May 2, 2010, at 11:10 AM, Sean Leather wrote: Or should I make my own class? Then, there obviously won't be any instances for existing types other than your own (which might be a good or bad thing). You may want to do this, if you don't want to require either (=) or (*), which may not be supported for reasonable instances of your own class. I don't really want to do this option, because it increases the understanding overhead needlessly, I think. Everything else that is provided by Applicative/Monad doesn't matter. I require only the three operations above and do not disallow extra operations. By not making your own class, you prohibit types that do not support * (or =). That's fine, but an additional burden to instance writers. By not listing extra operations in your own class you would not disallow them. You require them by not making your own class without them. Understood and agreed. Having my own class would be the most flexible in what it allows and disallows. But still, your wish to reuse existing classes may be a fine reason to impose an additional burden. There is an additional maintenance burden that I've recently become aware of, considering I haven't done a very good job of maintaining my own code. ;) To use my own class, I should reasonably provide instances for everything that I possibly can. This would include (at least) lists, Maybe, WrappedAlternative, and WrappedMonadPlus. Who knows? I may change my mind in a while. In that case, would you have any suggestions on a name for such a class or names for the methods? ;) class C f where zero :: f a one :: a - f a append :: f a - f a - f a Sean ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus or Alternative or ...?
would you have any suggestions on a name for such a class or names for the methods? I'm afraid I don't. I'd like class Pointed t where point :: a - t a class Monoid m where id :: m (.) :: m - m - m constraint Monoidy t = (Pointed t, Monoid (t a)) (although I'm not a big fan of the involved names except for the Monoid class) But the above is currently impractical for various reasons ;) (more than those listed in [1]). Sebastian [1] Haskell Type Constraints Unleashed http://www.cs.kuleuven.be/~toms/Research/papers/constraint_families.pdf -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus or Alternative or ...?
Check the laws that instances of MonadPlus and Alternative should comply with to help you make your decision. Cheers Mark Sean Leather wrote: I want to generalize a set of functions from lists to some functor type. I require the following three operation types. f a a - f a f a - f a - f a Should I choose MonadPlus and use these? mzero return mplus Or should I choose Alternative and use these? empty pure (|) Or should I make my own class? Or is there another option? Thanks, Sean ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
On Fri, May 09, 2008 at 08:39:38PM +0100, Andrew Coppin wrote: OK, so I feel I understand monads fine. I regularly use Maybe, [] and IO, and I've even constructed a few monads of my own. But here's a question: what is the purpose of the MonadPlus class? Clearly it defines a binary operation over monadic values and an identity element for that operation. But... what is this supposed to *do*? (For example, () has an almost identical signature to mplus. But presumably they don't both do the same thing...) What functionallity is this supposed to give you? MonadPlus is a crude way of achieving the catching of exceptional cases, and you should think of mplus as being equivalent to (catch . const). The trouble is that MonadPlus doesn't provide any mechanism for finding out what went wrong, so I've only ever found it useful when using the Maybe monad (which itself has no way of identifying what went wrong). [In a somewhat unrelated question... I saw some code the other day that used Either as if it were a monad. And yet, I don't see an instance given in the standard libraries - even though there should be one. I can see Functor (Either a), but not Monad (Either a) or even Monad (Either String)...] I am pretty certain that there is a monad instance for Either, but also don't know where it's defined. -- David Roundy Department of Physics Oregon State University ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
On Fri, May 9, 2008 at 2:39 PM, Andrew Coppin [EMAIL PROTECTED] wrote: [In a somewhat unrelated question... I saw some code the other day that used Either as if it were a monad. And yet, I don't see an instance given in the standard libraries - even though there should be one. I can see Functor (Either a), but not Monad (Either a) or even Monad (Either String)...] It's used in the Error Monad. -- Rich JID: [EMAIL PROTECTED] LOI: https://www.google.com/reader/shared/00900594587109808626 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
Andrew Coppin wrote: But here's a question: what is the purpose of the MonadPlus class? It gives you a way of working with monads as monoids. Consider a Parsec example: metasyntactic = text foo `mplus` text bar `mplus` text baz You'll get back whichever one matched, in left-to-right-order, or mzero (a parse failure) if all of them fail. b ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
Bryan O'Sullivan wrote: Andrew Coppin wrote: But here's a question: what is the purpose of the MonadPlus class? It gives you a way of working with monads as monoids. Consider a Parsec example: metasyntactic = text foo `mplus` text bar `mplus` text baz You'll get back whichever one matched, in left-to-right-order, or mzero (a parse failure) if all of them fail. ...so it's a kind of choice operator? Run all actions until you get to one that succeeds and return the result from that? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
On May 9, 2008, at 15:56 , Andrew Coppin wrote: Bryan O'Sullivan wrote: Andrew Coppin wrote: But here's a question: what is the purpose of the MonadPlus class? It gives you a way of working with monads as monoids. Consider a Parsec example: metasyntactic = text foo `mplus` text bar `mplus` text baz You'll get back whichever one matched, in left-to-right-order, or mzero (a parse failure) if all of them fail. ...so it's a kind of choice operator? Run all actions until you get to one that succeeds and return the result from that? In monadic guise that's how it's usually used, yes (since monoids like (+) are not generally all that useful as monads; (++) (list monad) and (.) (Monad ((-) r)) might be, though). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
On Fri, 2008-05-09 at 12:47 -0700, David Roundy wrote: On Fri, May 09, 2008 at 08:39:38PM +0100, Andrew Coppin wrote: OK, so I feel I understand monads fine. I regularly use Maybe, [] and IO, and I've even constructed a few monads of my own. But here's a question: what is the purpose of the MonadPlus class? Clearly it defines a binary operation over monadic values and an identity element for that operation. But... what is this supposed to *do*? (For example, () has an almost identical signature to mplus. But presumably they don't both do the same thing...) What functionallity is this supposed to give you? MonadPlus is a crude way of achieving the catching of exceptional cases, and you should think of mplus as being equivalent to (catch . const). The trouble is that MonadPlus doesn't provide any mechanism for finding out what went wrong, so I've only ever found it useful when using the Maybe monad (which itself has no way of identifying what went wrong). MonadPlus is a crude way of doing that, but that isn't the motivating example of MonadPlus, indeed, that arguably shouldn't be a MonadPlus instance. Cale Gibbard suggests (perhaps not originally) splitting MonadPlus into MonadPlus (and MonadZero) and MonadOrElse. They'd have essentially the same operations, but would be intended to satisfy different laws. Maybe, Either e, IO are better instances of MonadOrElse while [], Parser, LogicT, other non-determinism, parser, or concurrency monads would more appropriately be MonadPlus. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
Andrew Coppin wrote: ...so it's a kind of choice operator? Run all actions until you get to one that succeeds and return the result from that? In the context of Parsec, yes. In the grander scheme of things, the behaviour depends on whatever is appropriate for the particular monad you're working in. So, for example, mplus for lists is (++) and mzero is [], which is quite a different set of behaviours from the Parsec case. Usually, you can rely on MonadPlus behaving like a monoid. There are occasional exceptions, which is a mite upsetting. http://www.haskell.org/haskellwiki/MonadPlus b ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
On Fri, 2008-05-09 at 12:48 -0700, Bryan O'Sullivan wrote: Andrew Coppin wrote: But here's a question: what is the purpose of the MonadPlus class? It gives you a way of working with monads as monoids. I find this description mostly useless. Monads form monoids without being MonadPlus. instance Monad m = Monoid (m ()) where mempty = return () mappend = () You can form monoids out of Kleisli arrows, instance Monad m = Monoid (a - m a) where mempty = return mappend = (=) You could form monads into a monoid in another way, instance (Monad m, Monoid a) = Monoid (m a) mempty = return mempty mappend = liftM2 mappend So It gives you a way of working with monads as monoids. is significantly underspecified and doesn't actually say what MonadPlus means, let alone what it is intended for. A more interesting statement in that vein is: It gives you a way of working with monads as (distributive) near-rigs. This statement does actually encode some (all?) of the intended meaning of MonadPlus, e.g. mzero is intended to be a zero of () beyond simply being a unit for mplus. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
It sounds like the semantics of the MonadPlus methods are under-specified. I recall once writing a newtype wrapper to treat the same non-determinism monad with different mplus semantics, akin to cut versus backtracking. I think of MonadPlus as a less expressive version of msplit, from Backtracking, Interleaving, and Terminating Monad Transformers The Functional Pearl paper by Oleg Kiselyov, Chung-chieh Shan, Daniel P. Friedman and Amr Sabry. ICFP 2005. Is that an over-simplification? On Fri, May 9, 2008 at 3:12 PM, Bryan O'Sullivan [EMAIL PROTECTED] wrote: Andrew Coppin wrote: ...so it's a kind of choice operator? Run all actions until you get to one that succeeds and return the result from that? In the context of Parsec, yes. In the grander scheme of things, the behaviour depends on whatever is appropriate for the particular monad you're working in. So, for example, mplus for lists is (++) and mzero is [], which is quite a different set of behaviours from the Parsec case. Usually, you can rely on MonadPlus behaving like a monoid. There are occasional exceptions, which is a mite upsetting. http://www.haskell.org/haskellwiki/MonadPlus b ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
Andrew asked, ...so it's a kind of choice operator? Run all actions until you get to one that succeeds and return the result from that? The eternal bit of trickiness for Haskell is that type classes group often together things that people don't immediately see as similar - monads probably being the best example. So it's probably best not to immediately try to find an all-encompassing summary of MonadPlus like a kind of choice operator but instead concentrate on the definition. The key thing is the line mplus :: m a - m a - m a You can combine two m a's together with a binary operation to get another m a. Absolutely any binary operation (with an identity) that fits the rather lax laws that come with MonadPlus will do. Depending on context mplus might mean either/or, or and, or this first, or else that or something entirely different that nobody here has anticipated yet. For each monad m, just try to think about how you might combine a pair of m a's and what might serve as an identity. -- Dan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
On 10 May 2008, at 00:43, Dan Piponi wrote: Andrew asked, ...so it's a kind of choice operator? Run all actions until you get to one that succeeds and return the result from that? The eternal bit of trickiness for Haskell is that type classes group often together things that people don't immediately see as similar - monads probably being the best example. Well, that's the whole point of mathematics, isn't it? Mathematics is just a way to name different things with one word (opposed to philosophy, which is a way to name the same thing with different words). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus
Miguel said: Well, that's the whole point of mathematics, isn't it? Abstraction is common to mathematics and computing. But in computing the abstraction often follows lines that seem obvious. For example a GUI library might have a Widget class and people can immediately identify various regions of the screen with Widgets and know that when they want a new kind of device in their GUI it's time to define a widget. Although the Widget class may be technically defined by the interface it exposes, in practice people just think a gadget that can appear on the screen. Even someone who has never programmed can probably quickly guess what kinds of things correspond to instances of the Widget class. But mathematics is full of abstractions that aren't like this. Times modulo 24 hours and the way a closed loop can travel around a knot both form a group. The thing they have in common is that there's a binary operation with identity and inverses. Sometimes it can be more confusing to try to find a snappy English phrase that sums them up without restating the definition. Many common Haskell type classes lean towards the latter kind of abstraction. -- Dan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] MonadPlus instance for IO
that instance seems to be only in Control.Monad.Error in the 'mtl' package. It's not in the standard base package. You may need to import an mtl module to tell GHC to look there. Simon | -Original Message- | From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of | David Roundy | Sent: 02 February 2005 13:18 | To: haskell-cafe@haskell.org | Subject: [Haskell-cafe] MonadPlus instance for IO | | I'm sure I'm doing something stupid, but somehow ghc isn't recognizing the | existance of a MonadPlus instance for IO: | | DarcsIO.lhs:48: | No instance for (MonadPlus IO) | arising from use of `mplus' at DarcsIO.lhs:48 | In the definition of `foo': | foo = (fail aaack) `mplus` (fail foobar) | | Any idea what I'm doing wrong? I'm using | | $ ghc --version | The Glorious Glasgow Haskell Compilation System, version 6.2.2 | | packaged for debian. | -- | David Roundy | http://www.darcs.net | ___ | Haskell-Cafe mailing list | Haskell-Cafe@haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MonadPlus instance for IO
Am Mittwoch, 2. Februar 2005 14:48 schrieb David Roundy: On Wed, Feb 02, 2005 at 02:41:42PM +0100, Daniel Fischer wrote: Probably you haven't imported 'Control.Monad.Error', where the instance is defined. I did and all went well. Thanks, that did it. It's confusing that the instance is documented in Control.Monad. Yes, very confusing, but what could one do? Maybe urge people to mention instance declarations in the module description, so from the absence of one, you are led to look elsewhere. But that might make descriptions unduly large sometimes. Daniel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
