Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 11:24 PM, Ketil Malde wrote: > > You know, this might be the right time to start expanding our > vocabulary beyond seven bits.  Since we're likely to keep mappend > around as an alias for some time, people would have a grace period to > adjust. > > How about U+2295 (circle w

Re: [Haskell-cafe] Monoid wants a (++) equivalent

You know, this might be the right time to start expanding our vocabulary beyond seven bits. Since we're likely to keep mappend around as an alias for some time, people would have a grace period to adjust. How about U+2295 (circle with plus inside it)? Or, if we would like to stick to the 8-bit

Re: [Haskell-cafe] ORM for haskell?

Mads Lindstrøm writes: > I do not get this explanation, could you expand? I would have thought it > should be: "difference? Because SQLAlchemy knows about the relationships > (not relations, but relation_ships_), it do not have to explicitly join > on foreign keys.". I think this is a common ter

Re: [Haskell-cafe] Monoid wants a (++) equivalent

G'day all. On Tue, Jun 30, 2009 at 08:02:48PM -0400, Daniel Peebles wrote: But we don't want to imply it's commutative either. Having something "bidirectional" like <> or <+> feels more commutative than associative to me. Quoting John Meacham : Not really, think of '++', which doesn't commu

Re: [Haskell-cafe] Monoid wants a (++) equivalent

G'day all. Quoting John Meacham : (+>) seems to imply to me that the operator is non-associative. Something like (<>) or (<+>) would be better. I tend to agree. Moreover, and I realise this may be a losing battle, I want (++) to be the generic operator. I understand the argument. I even ag

Re: [Haskell-cafe] Monoid wants a (++) equivalent

Ok. When nobody can agree on a graphical operator can it be shortened to "mop" and "munit"? (Personally I'm for (++). (Yeah, I know.)) -ljr Daniel Peebles wrote: > But we don't want to imply it's commutative either. Having something > "bidirectional" like <> or <+> feels more commutative tha

Re: Re[2]: [Haskell-cafe] Re: Could FFI support pass-by-value of structs?

On Tue, Jun 30, 2009 at 01:18:32AM +0100, Duncan Coutts wrote: > On IA32 structs/unions passed as parameters go by value on the stack. > For structs/unions as function results, they are stored into a > caller-allocated area on the stack, pointed to by a "hidden" first arg. > > It's different on ea

Re: [Haskell-cafe] Haskell on JVM

Claus Reinke wrote: |Basically, the JVM lacks a native ability to do tail calls. It does |not have an instruction to remove/replace a stack frame without |executing an actual return to the calling method/function. There is a conflict between preserving stack layout and efficient tail calls. U

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 08:02:48PM -0400, Daniel Peebles wrote: > But we don't want to imply it's commutative either. Having something > "bidirectional" like <> or <+> feels more commutative than associative > to me. Not really, think of '++', which doesn't commute but is visually symmetric, or Da

Re: [Haskell-cafe] Monoid wants a (++) equivalent

But we don't want to imply it's commutative either. Having something "bidirectional" like <> or <+> feels more commutative than associative to me. On Tue, Jun 30, 2009 at 6:39 PM, John Meacham wrote: > On Tue, Jun 30, 2009 at 02:54:38PM -0400, Brent Yorgey wrote: >> On Tue, Jun 30, 2009 at 09:45:4

Re: [Haskell-cafe] Monoid wants a (++) equivalent

David Leimbach wrote: > > > On Tue, Jun 30, 2009 at 11:54 AM, Brent Yorgey > wrote: > > On Tue, Jun 30, 2009 at 09:45:45AM -0700, Bryan O'Sullivan wrote: > > I've thought for a while that it would be very nice indeed if > the Monoid > > class had a

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 3:56 PM, Ross Paterson wrote: > On Tue, Jun 30, 2009 at 03:39:39PM -0700, John Meacham wrote: > > (+>) seems to imply to me that the operator is non-associative. > > It does seem to imply some asymmetry between the arguments. > Well, the canonical instance of Monoid is to

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 03:39:39PM -0700, John Meacham wrote: > (+>) seems to imply to me that the operator is non-associative. It does seem to imply some asymmetry between the arguments. > Something like (<>) or (<+>) would be better. (<+>) is used in Control.Arrow. (<>) is used in Data.Sequen

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 3:50 PM, Dougal Stanton wrote: > > (+>) seems to imply to me that the operator is non-associative. Something > > like (<>) or (<+>) would be better. > > It's too similar to the applicative (*>), and implies all sorts of > things like different types of the two arguments an

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 11:39 PM, John Meacham wrote: > > (+>) seems to imply to me that the operator is non-associative. Something > like (<>) or (<+>) would be better. > It's too similar to the applicative (*>), and implies all sorts of things like different types of the two arguments and so on

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 02:54:38PM -0400, Brent Yorgey wrote: > On Tue, Jun 30, 2009 at 09:45:45AM -0700, Bryan O'Sullivan wrote: > > I've thought for a while that it would be very nice indeed if the Monoid > > class had a more concise operator for infix appending than "a `mappend` b". > > I wonder

Re: [Haskell-cafe] List spine traversal

seq allows you to distinguish (undefined) from (const undefined) case allows you to distinguish (undefined) from the pair (undefined, undefined) isFun f = f `seq` True isPair p = case p of (_,_) -> True isFun undefined -> undefined isFun (const undefined) -> True isPair undefined -> undefi

Re: [Haskell-cafe] ORM for haskell?

At Tue, 30 Jun 2009 19:52:08 +0200, Marc Weber wrote: > Is there anyone interested in helping building a library which > a) let's you define kind of model of you data > b) let's you store you model in any backend (maybe a relational > database) > c) does static checking of your queries at comp

Re: [Haskell-cafe] Leksah works!

Hi David, david48 wrote: > > > I would love to try leksah, but on my machine there a weird bug: I > can't type a space. When I press the space bar, nothing happens.( it > writes "CTRL-Space : Start complete" at the bottom though) > > ... Thats indeed strange, as we use standard gtk handling

Re: [Haskell-cafe] ORM for haskell?

Hi Mads! On Tue, Jun 30, 2009 at 11:49:40PM +0200, Mads Lindstrøm wrote: > Hi Marc Weber > > > Another example: Updating the age of a pupil: > > > > row = SELECT * FROM pupils where age = 13; > > UPDATE pupils SET age = 14 WHERE id = > > > > p = session.query(Pupil).filter(Pupil.age==13)

Re: [Haskell-cafe] ORM for haskell?

Hi Marc Weber > Another example: Updating the age of a pupil: > > row = SELECT * FROM pupils where age = 13; > UPDATE pupils SET age = 14 WHERE id = > > p = session.query(Pupil).filter(Pupil.age==13).one().age=14 > session.commit() > > difference? > You don't have to care about ids

Re: [Haskell-cafe] Leksah works!

On Tue, Jun 30, 2009 at 4:28 PM, jutaro wrote: > > As Leksah developer I approve your comment. > > Even better we will soon have a new release that integrates GHCi and a > !visual debugger! plus other useful features like much enhanced text search > with regex and grep and enhanced GUI framework wi

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 1:33 PM, Thomas Davie wrote: > I excellently think your proposal is a correct assessment. > Well then, here's the library enhancement ticket: http://hackage.haskell.org/trac/ghc/ticket/3339 ___ Haskell-Cafe mailing list Haskell

Re: [Haskell-cafe] ORM for haskell?

Hi Marc > Example why it matters: > schools - 1:n - teachers - 1:n - pupils > > If you want to list all schools which have a pupil with age > 3 you'd > write an sql query like this: > > SELECT dictinct * FROM schools as s JOIN teachers t ON (t.school_id = s.id) > JOIN pupils as p ON (p.teach

Re: [Haskell-cafe] List spine traversal

andrewhhunter: > On Mon, Jun 29, 2009 at 11:30 PM, Ryan Ingram wrote: > > There can't be a way to do so that is pure, because such a function > > could distinguish between > >> xs1 = () : xs1 > > and > >> xs2 = f () where f () = () : f () > > > > But doesn't seq and friends cause many of our norma

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On 30 Jun 2009, at 22:19, Daniel Fischer wrote: Am Dienstag 30 Juni 2009 20:56:10 schrieb David Leimbach: On Tue, Jun 30, 2009 at 11:54 AM, Brent Yorgey >wrote: On Tue, Jun 30, 2009 at 09:45:45AM -0700, Bryan O'Sullivan wrote: I've thought for a while that it would be very nice indeed if the

Re: [Haskell-cafe] List spine traversal

On Mon, Jun 29, 2009 at 11:30 PM, Ryan Ingram wrote: > There can't be a way to do so that is pure, because such a function > could distinguish between >> xs1 = () : xs1 > and >> xs2 = f () where f () = () : f () > But doesn't seq and friends cause many of our normal referential transparency guaran

Re: [Haskell-cafe] Monoid wants a (++) equivalent

Am Dienstag 30 Juni 2009 20:56:10 schrieb David Leimbach: > On Tue, Jun 30, 2009 at 11:54 AM, Brent Yorgey wrote: > > On Tue, Jun 30, 2009 at 09:45:45AM -0700, Bryan O'Sullivan wrote: > > > I've thought for a while that it would be very nice indeed if the > > > Monoid class had a more concise opera

Re: [Haskell-cafe] ANN: package Boolean: Generalized booleans

It compiles fine :-) If you want, you can take a look at this [1] version of the code (or the tarball [2]). Load Main.hs in GHCi and run `test`, it will evaluate to `True`. Then, in the source code, switch the type of `test` from `P.Bool` to `Js JsBool` (in the comments) and run `test` again, now

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 11:54 AM, Brent Yorgey wrote: > On Tue, Jun 30, 2009 at 09:45:45AM -0700, Bryan O'Sullivan wrote: > > I've thought for a while that it would be very nice indeed if the Monoid > > class had a more concise operator for infix appending than "a `mappend` > b". > > I wonder if o

Re: [Haskell-cafe] ORM for haskell?

It has to do with treating groups of records from a table like an object. You have the object Employee, which consists of rows from the Person table, the Account table and the Building table. When you instantiate the object. if you don't ask to view the Employee's building information, it doesn't b

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 09:45:45AM -0700, Bryan O'Sullivan wrote: > I've thought for a while that it would be very nice indeed if the Monoid > class had a more concise operator for infix appending than "a `mappend` b". > I wonder if other people are of a similar opinion, and if so, whether this > i

Re: [Haskell-cafe] Monoid wants a (++) equivalent

Except that in this case the operator is associative :P On Tue, Jun 30, 2009 at 2:42 PM, David Leimbach wrote: > > > On Tue, Jun 30, 2009 at 10:04 AM, Bryan O'Sullivan > wrote: >> >> On Tue, Jun 30, 2009 at 9:50 AM, David Leimbach wrote: >>> >>> I actually worry that this will make people think,

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 10:04 AM, Bryan O'Sullivan wrote: > On Tue, Jun 30, 2009 at 9:50 AM, David Leimbach wrote: > >> I actually worry that this will make people think, more incorrectly, that >> Monoids are about appending stuff only. >> > > I think that adding a graphical operator as a synonym

Re: [Haskell-cafe] Making a strict (non-lazy) GCL Interpreter

Thanks Ketil, I'll try to give that a try, but as I said beforen, I don't know anything about monads, and since this project is for next monday and I have many other projects for the University for next week too I can't learn them right now... What I need to do is randomly select an element from

Re: [Haskell-cafe] ORM for haskell?

I don't have a good answer to your question, but I'm curious of how lazy loading of SQL-based records would work. It seems like having another user of the database modify your record before you've loaded it all could lead to an inconsistent record (assuming you've already loaded and memoized some f

Re: [Haskell-cafe] ANN: package Boolean: Generalized booleans

Does this code compile? I'd expect that instance Bool (Js JsBool) (Js r) where violates the fundep, since it applies for *all* values of r, not just to one. - Conal On Tue, Jun 30, 2009 at 8:53 AM, Sebastiaan Visser wrote: > On Jun 30, 2009, at 5:24 PM, Conal Elliott wrote: > >> Hi Sebas

Re: [Haskell-cafe] Suggestions for simulating Object ID

Hi, On 30.06.2009, at 11:55, Hemanth Kapila wrote: Can some one please suggest something on simulating some sort of "object-Ids" in Haskell? I mean, something like the following relation will hold: > a1 == a2 = (objectID a1) == (objectID a2) I am not quite sure but perhaps Stable Names a

Re: [Haskell-cafe] How to read safely?

The package ChristmasTree includes an alternative version of read which catches (and repairs if you want) errors. The package contains the code of the paper @inproceedings{1411296, author = {Marcos Viera and S. Doaitse Swierstra and Eelco Lempsink}, title = {Haskell, do you read me?: constructi

[Haskell-cafe] ORM for haskell?

Some time ago I stumbled upon SQLAlchemy which is a great ORM wrapper library for python. It has a nice syntax I'd like to see in a haskell library as well. SQLAlchemy already provides some lazy features such as loading subitems on access etc. All haskell SQL libraries I know only let you run SQL

Re: [Haskell-cafe] Monoid wants a (++) equivalent

Isn't "++" itself the perfect Monoid operator? Lambdabot seems to think so. On Tue, Jun 30, 2009 at 13:04, Edward Kmett wrote: > I love the idea, but its tricky to come up with one that is good that won't > break a lot of user code that imports Data.Monoid unqualified. > -Edward Kmett > > On Tue,

Re: [Haskell-cafe] Monoid wants a (++) equivalent

I love the idea, but its tricky to come up with one that is good that won't break a lot of user code that imports Data.Monoid unqualified. -Edward Kmett On Tue, Jun 30, 2009 at 12:45 PM, Bryan O'Sullivan wrote: > I've thought for a while that it would be very nice indeed if the Monoid > class ha

Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Tue, Jun 30, 2009 at 9:50 AM, David Leimbach wrote: > I actually worry that this will make people think, more incorrectly, that > Monoids are about appending stuff only. > I think that adding a graphical operator as a synonym for mappend would actually help to address that, since the magic wo

[Haskell-cafe] Monoid wants a (++) equivalent

I've thought for a while that it would be very nice indeed if the Monoid class had a more concise operator for infix appending than "a `mappend` b". I wonder if other people are of a similar opinion, and if so, whether this is worth submitting a libraries@ proposal over. ___

Re: [Haskell-cafe] Suggestions for simulating Object ID

On Tue, Jun 30, 2009 at 9:16 AM, Felipe Lessa wrote: > On Tue, Jun 30, 2009 at 07:57:07PM +0530, Hemanth Kapila wrote: >> Can't we come up with something like this staying within the >> limits of purity? > > No, because that would break referential transparency :(. I.e., > it would be possible to

Re: [Haskell-cafe] Suggestions for simulating Object ID

On Tue, Jun 30, 2009 at 07:57:07PM +0530, Hemanth Kapila wrote: > Can't we come up with something like this staying within the > limits of purity? No, because that would break referential transparency :(. I.e., it would be possible to distinguish things that should be "equal", such as '3' from '1

Re: [Haskell-cafe] Re: Reflections on the ICFP 2009 programming contest

The main thing my team implemented in Haskell was a simulator simulator that took the first two rounds worth of port information and used that to back into the velocity for each of the satellites. This meant we really only had to appeal to the actual VM implementation for canonical scoring and to v

Re: [Haskell-cafe] Leksah works!

I would love to have a standalone Mac OS X compatible build to try. As it stands, I have not been successful getting a Cocoa/Carbon GTK running on Leopard, and can't afford the time to fight with making it work. I too typically use Emacs, but also like to use Yi once in a while as well. Dave On

Re: [Haskell-cafe] ANN: package Boolean: Generalized booleans

On Jun 30, 2009, at 5:24 PM, Conal Elliott wrote: Hi Sebastiaan, I like your extensions of generalized booleans to other common Haskell types! I also prefer using type families to fundeps. In this case I didn't because of some awkwardness with vector operations, but I'm going to try aga

Re: [Haskell-cafe] ANN: package Boolean: Generalized booleans

Hi Sebastiaan, I like your extensions of generalized booleans to other common Haskell types! I also prefer using type families to fundeps. In this case I didn't because of some awkwardness with vector operations, but I'm going to try again. I'm confused about your particular fundep choice. For

Re: [Haskell-cafe] Leksah works!

As Leksah developer I approve your comment. Even better we will soon have a new release that integrates GHCi and a !visual debugger! plus other useful features like much enhanced text search with regex and grep and enhanced GUI framework with a tentative support for multiple screens. So stay tu

Re: [Haskell-cafe] Suggestions for simulating Object ID

Thank you. It looks perfect for now. Just that I can create it only inside an IO (newUnique is of type IO Unique) Perhaps it involves some magic with random numbers or system time. Can't we come up with something like this staying within the limits of purity? Thanks Hemanth On 6/30/09, Fe

[Haskell-cafe] [help] Creating the simplest possible adhoc network

Hi. I'm in the quest of exploring adhoc networks together with Haskell. Both are quite new to me. I found the http://hackage.haskell.org/package/adhoc-network-1.0.3 adhoc package in Hackage, it's made for the p2p chat client http://hackage.haskell.org/package/Barracuda Barracuda . I've tried to

[Haskell-cafe] RE: 6.12.1 planning

I've dumped all this on a release plans wiki page: http://hackage.haskell.org/trac/ghc/wiki/Status/Releases Manuel, Duncan: maybe you can modify the wiki directly? Simon | -Original Message- | From: glasgow-haskell-users-boun...@haskell.org [mailto:glasgow-haskell-users- | boun..

Re: [Haskell-cafe] Breaking ghci

Hi guys, actually it involved haskelldb and a table that had 183 columns. In order to specify the table with its 183 columns I had to increase the context-stack slightly from 20 to a mere 190. Günther BTW there is one thing I find a bit unfortunate in otherwise flawless haskelldb, each colu

Re: [Haskell-cafe] Suggestions for simulating Object ID

On Tue, Jun 30, 2009 at 03:25:26PM +0530, Hemanth Kapila wrote: > Can some one please suggest something on simulating some sort of > "object-Ids" in Haskell? Data.Unique[1]? [1] http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-Unique.html -- Felipe.

[Haskell-cafe] Re: BerkeleyDBXML linking problems.

(crosspost from haskell-libraries) Hello all, again. Meanwhile I've been able to install this package without too much trouble on a Linux system. Unfortunately MacOSX is still a problem. Both on Linux and Mac I installed the Berkeley DB and DBXML packages with `--prefix=/usr' so all includ

Re: [Haskell-cafe] 6.12.1 planning

2009/6/30 Simon Marlow : > Hi Folks, > > As usual, we're planning a major release of GHC around September. Here's our > list of the main items currently scheduled for 6.12.1, and their status. If > you have the time and inclination to help with any of these, please get > involved! > > * Parallel p

[Haskell-cafe] 6.12.1 planning

Hi Folks, As usual, we're planning a major release of GHC around September. Here's our list of the main items currently scheduled for 6.12.1, and their status. If you have the time and inclination to help with any of these, please get involved! * Parallel performance. 6.12.1 will ship with

Re: [Haskell-cafe] Leksah works!

Hi, Thanks for the update. I just tried it and it is quite cool.Atlhough I am too addicted to emacs and can't imagine leaving it (at least before hIDE), I still think leksah is quite useful. Thanks again On Tue, Jun 30, 2009 at 10:45 AM, Eugene Kirpichov wrote: > Hi. > Quite a while ago I lau

Re: [Haskell-cafe] coding standard question

2009/6/22 Malcolm Wallace : > Erik de Castro Lopo wrote: > >> Vasili I. Galchin wrote: >> >> >  "where/let" functions use the >> > same name for function parameters as the outer function and hence >> > there is a "shadow" warning from the compiler. >> >> In Haskell there is an easy way around this

[Haskell-cafe] Suggestions for simulating Object ID

Hello all, Can some one please suggest something on simulating some sort of "object-Ids" in Haskell? I mean, something like the following relation will hold: > a1 == a2 = (objectID a1) == (objectID a2) Currently I have something like > import Data.Hash >import qualified Data.ByteString.Char8 a

Re: [Haskell-cafe] Wondering about c type in haskell.

On Tue, Jun 30, 2009 at 10:01:48AM +0800, Magicloud Magiclouds wrote: > Hi, > There are times, when we need to make some system calls, or call C > library. So we have to deal with C data types. > For example, CPid, which is an integer, actually. So we can do > "fromIntegral pid". Then why do no

Re: [Haskell-cafe] Making a strict (non-lazy) GCL Interpreter

Hector Guilarte writes: > I need to randomly select ONE of the valid conditions and execute it's > instruction. I know there is a Random Monad, but it returns an IO > Int, No, this is not right. Values in the Random monad are computations that rely on randomness, but they can produce values o

Re: [Haskell-cafe] Breaking ghci

Günther Schmidt wrote: >> ...*I* >> have managed to write code that ghc is not even able to compile due to >> exhausting virtual memory! >> Top that! Good work Günther! Joe Fredette wrote: > Code or it didn't happen. :) Yes, how did you do it? Did it involve very large literals? GHC is known to

Re: [Haskell-cafe] ANN: package Boolean: Generalized booleans

On Jun 30, 2009, at 2:44 AM, Conal Elliott wrote: I just uploaded a new package [1] for generalized booleans, which provides type classes with generalizations of boolean values & operations, if-then-else, Eq and Ord. These values & types come up for me with every new deep DSEL, and I think

Re: [Haskell-cafe] [: Where the bracket things are? :]

But it won't help to get the knowledge of GHC's internal he was after... Thu 2009/6/29 Robert Greayer : > You can use QuasiQuotation, where your bracketing syntax looks like: > > [$foo| blah blah blah |] > > and 'foo' represents a quasi-quoter, and the stuff inside the brackets > is any arbitrary