Re: [Haskell-cafe] Are there any gay haskelleres?
I'm sure there's some theory about fags being unable to use tools and stuff. It certainly cannot be anything to do with cultural pressure. Perhaps it is easy to mistake a male-dominated field for one that males are intrinsically good at, but really, have a look at the Y chromosome, it does nobody any favours. Gender is hormonal. Me too, by the way. cheers, Fraser. 2010/3/28 Keith Sheppard keiths...@gmail.com Hello, I am one. Best Keith 2010/3/28 Günther Schmidt gue.schm...@web.de: Hi guys, are there any gay haskellers? ... Since the first one was so much fun ;) Günther ___ 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 -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Are there any gay haskelleres?
I suppose it's easy to miss the underlying sexism when you aren't affected by it. 2010/3/28 Günther Schmidt gue.schm...@web.de Hi guys, judging by the responses so far it seems that the gay haskellers have more balls than the female haskellers to come out of the closet. Uhm. Günther Am 28.03.10 19:15, schrieb Günther Schmidt: Hi guys, are there any gay haskellers? ... Since the first one was so much fun ;) Günther ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Language simplicity
On Tue, Jan 12, 2010 at 11:26 PM, Daniel Fischer
daniel.is.fisc...@web.dewrote:
Okay, 'as' is easy. But can you find a situation where 'qualified' or
'hiding' would be natural choices for an identifier? I'd love to see those
in some code :)
module LordsOfMidnight.Character(Character) where
data Character = C { name :: String,
location :: (Int,Int),
facing :: Direction,
hour :: Int,
energy :: Int,
fear :: Int,
riders :: Int,
soldiers :: Int,
hiding :: Bool
}
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[Haskell-cafe] Re: grapefruit Grapefruit infrastructure
I'm Switzerland on open source licenses -- I use GPL3 on everything I write, because I like the default position, but I'm always happy to relicense on request (except maybe to companies like Fluffy Bunny Killer, Inc). My sister tells me I'm a control freak, and maybe I am :-) So BSD is just great for me. cheers, Fraser. On Thu, Feb 26, 2009 at 11:46 AM, Wolfgang Jeltsch g9ks1...@acme.softbase.org wrote: Hello, I just want to mention that the Grapefruit FRP library now has a mailing list and a Trac instance which contains a bug tracker. See: http://www.haskell.org/haskellwiki/Grapefruit#Community Please also note that the Grapefruit repositories have moved to code.haskell.org. Best wishes, Wolfgang ___ Grapefruit mailing list grapefr...@projects.haskell.org http://projects.haskell.org/cgi-bin/mailman/listinfo/grapefruit -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functional GUIs again
The current darcs version now mentions the 0.9.13 dependency. I don't see a nice way of supporting both 0.9.13 and 0.10.0, so I'll take the plunge and do a destructive upgrade. As you say, the new model/view is much nicer (and of course I shall be stealing liberally from it). cheers, Fraser. On Tue, Feb 17, 2009 at 11:16 AM, Peter Verswyvelen bugf...@gmail.comwrote: Okay, you used 0.9.13, that explains the errors yes, the model/view thing is different in 0.10.0 (better IMHO) Yes it would be nice if it worked with GTK2HS 0.10.0, but it might be tricky to support both version, I don't know. On Tue, Feb 17, 2009 at 12:51 AM, Fraser Wilson blancoli...@gmail.comwrote: Hi Peter, Thanks! I haven't tried to compile with 0.10.0 but I can guess that the errors arise from the use of ListStore. I'm not sure what the best approach is here. Is 0.9.13 over now? If so, then I'll upgrade and fix it. For now it would certainly make sense to put the dependency into the cabal file, which I'm ashamed to say never occorred to me. cheers, Fraser On 17 feb 2009, at 00:29, Peter Verswyvelen bugf...@gmail.com wrote: That's some great hacking you did :-) What version of GTK2HS did you use? I get various compiler errors when using the latest GTK2HS 0.10.0. Cheers, Peter 2009/2/16 Fraser Wilson blancoli...@gmail.comblancoli...@gmail.com Now that I re-read my email, it looks like I'm saying Username requested in the sense of OK, Cafe people, treat this as a user name request and step to it. What I meant was that I have requested a username (via the email), and once I have an account I'll put it on hackage. Sorry for the confusion. Also, a patch that derives the Monoid instance for Style has been pushed. Let me explain why I love this mailing list. I hadn't really looked at Monoids, but then their utility fell out of the recent discussion about whether they should be called Monoids or ... whatever the other name was. And now I see them all over the place, and I'm a better person for it. Surely this is too much to be considered actual programming! cheers, Fraser. On Mon, Feb 16, 2009 at 10:40 PM, Duncan Coutts duncan.cou...@worc.ox.ac.uk duncan.cou...@worc.ox.ac.uk wrote: On Mon, 2009-02-16 at 20:30 +0100, Fraser Wilson wrote: You must have missed the bit about congenitally lazy :-) Username requested ... See http://hackage.haskell.org/packages/accounts.html http://hackage.haskell.org/packages/accounts.html All you need to do is email Ross and ask. Duncan -- http://thewhitelion.org/mysisterhttp://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.orgHaskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe http://www.haskell.org/mailman/listinfo/haskell-cafe -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Low-level high-level languages?
What was that stripped-down low-level version of C I saw coming out of ... was it Microsoft Research? C-- or something. Unfortunately, the name appears to be immune to Googling. 2009/2/16 Alberto G. Corona agocor...@gmail.com http://www.ats-lang.org/ 2009/2/16 Jon Fairbairn jon.fairba...@cl.cam.ac.uk Maurício briqueabra...@yahoo.com writes: Hi, I've checked this 'BitC' language (www.bitc-lang.org). It uses some ideas we see in Haskell, although with different realization, and target mainly reliable low level code, like micro-kernels (although I think it could be used anywhere C is also used, including writing libraries Haskell could call with FFI). Do you guys know of other languages like that that I could check? Hume http://www-fp.cs.st-andrews.ac.uk/hume/index.shtml might be worth a look. I've never tried it, and since one of the top chaps associated with it said to me that he loathes Haskell, I'm not sure I should mention it here :-) -- Jón Fairbairn jon.fairba...@cl.cam.ac.uk http://www.chaos.org.uk/~jf/Stuff-I-dont-want.htmlhttp://www.chaos.org.uk/%7Ejf/Stuff-I-dont-want.html (updated 2009-01-31) ___ 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 -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: The Typeclassopedia, and request for feedback
Super! Also, best definition of bottom I've yet seen -- ignoring _|_, which is a party pooper. Like good code, it's short, to the point, and obviously correct. Thanks for this. It's great to have it all in one place, and so entertainingly presented. cheers, Fraser. On Mon, Feb 16, 2009 at 10:29 AM, Brent Yorgey byor...@seas.upenn.eduwrote: Hi all, If you've noticed the lack of a HWN this week, that's because I've been doggedly finishing my article entitled 'The Typeclassopedia', which I have just submitted for publication in the Monad.Reader. Here's the abstract: The standard Haskell libraries feature a number of type classes with algebraic or categorical underpinnings. Becoming a fluent Haskell hacker requires intimate familiarity with them all, yet acquiring this familiarity often involves combing through a mountain of tutorials, blog posts, mailing list archives, and IRC logs. The goal of this article is to serve as a starting point for the student of Haskell wishing to gain a firm grasp of its standard type classes. The essentials of each type class are introduced, with examples, commentary, and extensive references for further reading. My hope is that this will be a valuable resource to the Haskell community, especially those who are learning. Any feedback would be greatly appreciated, especially if it helps improve the article before publication. A draft can be found here: http://www.cis.upenn.edu/~byorgey/papers/typeclassopedia-draft-090216.pdfhttp://www.cis.upenn.edu/%7Ebyorgey/papers/typeclassopedia-draft-090216.pdf Also see my blog post for a bit more info: http://byorgey.wordpress.com/2009/02/16/the-typeclassopedia-request-for-feedback/ happy haskelling! -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] ANNOUNCE: first Grapefruit release
Yeah, I lack some darcs fu unfortunately. I understood it was just a matter of copying a repository. I'll have a look, and by have a look I mean bother #haskell :-) Cheers, Fraser Sent from my iPhone On 16 feb 2009, at 18:51, Wolfgang Jeltsch g9ks1...@acme.softbase.org wrote: Am Montag, 16. Februar 2009 18:05 schrieb Fraser Wilson: I'd love to hack on Grapefruit. That’s great! I'll do some study (and take a break from my own world-changing functional GUI :-) I tried to check out your repository at http://thewhitelion.org/darcs/barrie/ but darcs get failed with some complaint about cached patches or so. :-( I use darcs 2.2.1. Best wishes, Wolfgang ___ 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
[Haskell-cafe] Functional GUIs again
Since I'm congenitally lazy, and writing a GUI by hand in the IO monad is ... not what I expect from a beautiful program, and because what I often need is a GUI that manipulates a state, and because I don't understand arrows, and having been intrigued by a recent cafe thread, I threw together a prototype GUI library with the following features: - the GUI is defined on three levels: gadgets, widgets and styles - gadgets are functions on a state - widgets are data structures which define the layout - styles are ways to modify the appearance of widgets The following quick example shows a text box and a button. Clicking on the button reverses the text in the text box. module Main where import Barrie demoWidget :: Widget demoWidget = vbox [ui demo entry textBox, ui demo command (labelButton click me)] type DemoState = String type DemoGadget = Gadget DemoState demoGUI :: DemoGadget demoGUI = localG demo gui [editorG demo entry id const, commandG demo command reverse] main = gtkMain demoGUI demoWidget Hello, world Two gadgets are used: editorG :: String - (a - b) - (b - a - a) - Gadget a commandG :: String - (a - a) - Gadget a The editor gadget can show a value from a state, and update a state with a value. The command gadget can transform a state to a new state. gtkMain connects the gadgets to a widget, which specifies layout using the vbox, attaching the editor gadget to a text box, and the command gadget to a button. Well, that's all pretty trivial. The key thing for me was that I can easily slap a GUI onto the the front of a class of applications, which happen to be the sort of applications I've been writing lately. Also, arbitrary parts of the GUI can respond to things that happen miles away, without really having to worry about it too much. In barrie-0.1 and 0.2, which used stream-based approaches, the problem of getting state from one end of the application to the other was non-trivial. I'll sketch another quick example: data BridgeGame = ... And a bunch of things you can do with the state: makeBid :: Bid - BridgeGame - BridgeGame playCard :: Card - BridgeGame - BridgeGame For bidding, each bid is represented by a gadget: bidG :: Bid - Gadget BridgeGame bidG bid = enabled (bidOK bid) $ CommandG (show bid) (makeBid bid) 'enabled' switches the gadget on if its first argument returns true when applied to the current state. However, the decision about what to do with a disabled gadget is made by its corresponding widget. We get one button for each bid: biddingG :: Gadget BridgeGame biddingG = localG bidding (map bidG allBids) And they can be displayed in any old order using a widget: biddingW :: Widget biddingW = vbox (map suitBids [Club, Diamond, Heart, Spade] ++ [ntBids]) where suitBids suit = hbox $ map (bidButton . flip Bid suit) [1 .. 7] ntBids = hbox $ map (bidButton . NT) [1 .. 7] bidButton bid = ui (show bid) $ labelButton (show bid) (You're right, double, redouble and pass are not represented. They make the lines too long). Screenshot here: http://thewhitelion.org/images/4D.png I've just bid four diamonds, so everything lower than that is automatically disabled. Currently, Barrie implements buttons, text boxes, labels, vertical/horizontal layout, single-column lists and drop lists. It current uses Gtk2hs for rendering, but it's GUI-agnostic (in fact, the first renderer was putStrLn/getLine). You can have a look by using darcs: darcs get http://thewhitelion.org/darcs/barrie Or get the tarball at http://thewhitelion.org/haskell/barrie-0.3.0-src.tar.gz One note: this is not intended to be a theoretically sound approach, merely a way of getting something done quickly. I would expect it to be most useful in putting a GUI front-end onto an existing application, in particular, an application that is driven by user actions which update a state; e.g. a calculator, a bridge game, a 4th edition DD character creator (but that leads to a critical mass of nerdiness, so it's off the table for now) cheers, Fraser. -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functional GUIs again
You must have missed the bit about congenitally lazy :-) Username requested ... cheers, Fraser. On Mon, Feb 16, 2009 at 8:10 PM, Lennart Augustsson lenn...@augustsson.netwrote: Put it on hackage! 2009/2/16 Fraser Wilson blancoli...@gmail.com: Since I'm congenitally lazy, and writing a GUI by hand in the IO monad is ... not what I expect from a beautiful program, and because what I often need is a GUI that manipulates a state, and because I don't understand arrows, and having been intrigued by a recent cafe thread, I threw together a prototype GUI library with the following features: - the GUI is defined on three levels: gadgets, widgets and styles - gadgets are functions on a state - widgets are data structures which define the layout - styles are ways to modify the appearance of widgets The following quick example shows a text box and a button. Clicking on the button reverses the text in the text box. module Main where import Barrie demoWidget :: Widget demoWidget = vbox [ui demo entry textBox, ui demo command (labelButton click me)] type DemoState = String type DemoGadget = Gadget DemoState demoGUI :: DemoGadget demoGUI = localG demo gui [editorG demo entry id const, commandG demo command reverse] main = gtkMain demoGUI demoWidget Hello, world Two gadgets are used: editorG :: String - (a - b) - (b - a - a) - Gadget a commandG :: String - (a - a) - Gadget a The editor gadget can show a value from a state, and update a state with a value. The command gadget can transform a state to a new state. gtkMain connects the gadgets to a widget, which specifies layout using the vbox, attaching the editor gadget to a text box, and the command gadget to a button. Well, that's all pretty trivial. The key thing for me was that I can easily slap a GUI onto the the front of a class of applications, which happen to be the sort of applications I've been writing lately. Also, arbitrary parts of the GUI can respond to things that happen miles away, without really having to worry about it too much. In barrie-0.1 and 0.2, which used stream-based approaches, the problem of getting state from one end of the application to the other was non-trivial. I'll sketch another quick example: data BridgeGame = ... And a bunch of things you can do with the state: makeBid :: Bid - BridgeGame - BridgeGame playCard :: Card - BridgeGame - BridgeGame For bidding, each bid is represented by a gadget: bidG :: Bid - Gadget BridgeGame bidG bid = enabled (bidOK bid) $ CommandG (show bid) (makeBid bid) 'enabled' switches the gadget on if its first argument returns true when applied to the current state. However, the decision about what to do with a disabled gadget is made by its corresponding widget. We get one button for each bid: biddingG :: Gadget BridgeGame biddingG = localG bidding (map bidG allBids) And they can be displayed in any old order using a widget: biddingW :: Widget biddingW = vbox (map suitBids [Club, Diamond, Heart, Spade] ++ [ntBids]) where suitBids suit = hbox $ map (bidButton . flip Bid suit) [1 .. 7] ntBids = hbox $ map (bidButton . NT) [1 .. 7] bidButton bid = ui (show bid) $ labelButton (show bid) (You're right, double, redouble and pass are not represented. They make the lines too long). Screenshot here: http://thewhitelion.org/images/4D.png I've just bid four diamonds, so everything lower than that is automatically disabled. Currently, Barrie implements buttons, text boxes, labels, vertical/horizontal layout, single-column lists and drop lists. It current uses Gtk2hs for rendering, but it's GUI-agnostic (in fact, the first renderer was putStrLn/getLine). You can have a look by using darcs: darcs get http://thewhitelion.org/darcs/barrie Or get the tarball at http://thewhitelion.org/haskell/barrie-0.3.0-src.tar.gz One note: this is not intended to be a theoretically sound approach, merely a way of getting something done quickly. I would expect it to be most useful in putting a GUI front-end onto an existing application, in particular, an application that is driven by user actions which update a state; e.g. a calculator, a bridge game, a 4th edition DD character creator (but that leads to a critical mass of nerdiness, so it's off the table for now) cheers, Fraser. -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functional GUIs again
Oh, cheers! Newtype deriving is more general than I expected. Thanks for
the comment.
I've requested a hackage account, so I expect it to be there shortly :-)
cheers,
Fraser.
On Mon, Feb 16, 2009 at 9:12 PM, Ryan Ingram ryani.s...@gmail.com wrote:
Tiny code-review comment:
data Style = Style [(String, StyleValue)]
deriving (Read, Show)
instance Monoid Style where
mempty = Style []
mappend (Style xs) (Style ys) = Style (xs ++ ys)
=
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
newtype Style = Style [(String, StyleValue)]
deriving (Read, Show, Monoid)
Also, put it on hackage! :) It looks pretty cool.
-- ryan
2009/2/16 Fraser Wilson blancoli...@gmail.com:
Since I'm congenitally lazy, and writing a GUI by hand in the IO monad is
... not what I expect from a beautiful program, and because what I often
need is a GUI that manipulates a state, and because I don't understand
arrows, and having been intrigued by a recent cafe thread, I threw
together
a prototype GUI library with the following features:
- the GUI is defined on three levels: gadgets, widgets and styles
- gadgets are functions on a state
- widgets are data structures which define the layout
- styles are ways to modify the appearance of widgets
The following quick example shows a text box and a button. Clicking on
the
button reverses the text in the text box.
module Main where
import Barrie
demoWidget :: Widget
demoWidget = vbox [ui demo entry textBox,
ui demo command (labelButton click me)]
type DemoState = String
type DemoGadget = Gadget DemoState
demoGUI :: DemoGadget
demoGUI = localG demo gui [editorG demo entry id const,
commandG demo command reverse]
main = gtkMain demoGUI demoWidget Hello, world
Two gadgets are used:
editorG :: String - (a - b) - (b - a - a) - Gadget a
commandG :: String - (a - a) - Gadget a
The editor gadget can show a value from a state, and update a state with
a
value. The command gadget can transform a state to a new state. gtkMain
connects the gadgets to a widget, which specifies layout using the vbox,
attaching the editor gadget to a text box, and the command gadget to a
button.
Well, that's all pretty trivial. The key thing for me was that I can
easily
slap a GUI onto the the front of a class of applications, which happen to
be
the sort of applications I've been writing lately. Also, arbitrary parts
of
the GUI can respond to things that happen miles away, without really
having
to worry about it too much. In barrie-0.1 and 0.2, which used
stream-based
approaches, the problem of getting state from one end of the application
to
the other was non-trivial.
I'll sketch another quick example:
data BridgeGame = ...
And a bunch of things you can do with the state:
makeBid :: Bid - BridgeGame - BridgeGame
playCard :: Card - BridgeGame - BridgeGame
For bidding, each bid is represented by a gadget:
bidG :: Bid - Gadget BridgeGame
bidG bid = enabled (bidOK bid) $ CommandG (show bid) (makeBid bid)
'enabled' switches the gadget on if its first argument returns true when
applied to the current state. However, the decision about what to do
with a
disabled gadget is made by its corresponding widget.
We get one button for each bid:
biddingG :: Gadget BridgeGame
biddingG = localG bidding (map bidG allBids)
And they can be displayed in any old order using a widget:
biddingW :: Widget
biddingW = vbox (map suitBids [Club, Diamond, Heart, Spade] ++ [ntBids])
where suitBids suit = hbox $ map (bidButton . flip Bid suit) [1 .. 7]
ntBids = hbox $ map (bidButton . NT) [1 .. 7]
bidButton bid = ui (show bid) $ labelButton (show bid)
(You're right, double, redouble and pass are not represented. They make
the
lines too long).
Screenshot here: http://thewhitelion.org/images/4D.png
I've just bid four diamonds, so everything lower than that is
automatically
disabled.
Currently, Barrie implements buttons, text boxes, labels,
vertical/horizontal layout, single-column lists and drop lists. It
current
uses Gtk2hs for rendering, but it's GUI-agnostic (in fact, the first
renderer was putStrLn/getLine).
You can have a look by using darcs:
darcs get http://thewhitelion.org/darcs/barrie
Or get the tarball at
http://thewhitelion.org/haskell/barrie-0.3.0-src.tar.gz
One note: this is not intended to be a theoretically sound approach,
merely
a way of getting something done quickly. I would expect it to be most
useful in putting a GUI front-end onto an existing application, in
particular, an application that is driven by user actions which update a
state; e.g. a calculator, a bridge game, a 4th edition DD character
creator
(but that leads to a critical mass of nerdiness, so it's off the table
Re: [Haskell-cafe] Functional GUIs again
Now that I re-read my email, it looks like I'm saying Username requested in the sense of OK, Cafe people, treat this as a user name request and step to it. What I meant was that I have requested a username (via the email), and once I have an account I'll put it on hackage. Sorry for the confusion. Also, a patch that derives the Monoid instance for Style has been pushed. Let me explain why I love this mailing list. I hadn't really looked at Monoids, but then their utility fell out of the recent discussion about whether they should be called Monoids or ... whatever the other name was. And now I see them all over the place, and I'm a better person for it. Surely this is too much to be considered actual programming! cheers, Fraser. On Mon, Feb 16, 2009 at 10:40 PM, Duncan Coutts duncan.cou...@worc.ox.ac.uk wrote: On Mon, 2009-02-16 at 20:30 +0100, Fraser Wilson wrote: You must have missed the bit about congenitally lazy :-) Username requested ... See http://hackage.haskell.org/packages/accounts.html All you need to do is email Ross and ask. Duncan -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functional GUIs again
Hi Peter, Thanks! I haven't tried to compile with 0.10.0 but I can guess that the errors arise from the use of ListStore. I'm not sure what the best approach is here. Is 0.9.13 over now? If so, then I'll upgrade and fix it. For now it would certainly make sense to put the dependency into the cabal file, which I'm ashamed to say never occorred to me. cheers, Fraser On 17 feb 2009, at 00:29, Peter Verswyvelen bugf...@gmail.com wrote: That's some great hacking you did :-) What version of GTK2HS did you use? I get various compiler errors when using the latest GTK2HS 0.10.0. Cheers, Peter 2009/2/16 Fraser Wilson blancoli...@gmail.com Now that I re-read my email, it looks like I'm saying Username requested in the sense of OK, Cafe people, treat this as a user name request and step to it. What I meant was that I have requested a username (via the email), and once I have an account I'll put it on hackage. Sorry for the confusion. Also, a patch that derives the Monoid instance for Style has been pushed. Let me explain why I love this mailing list. I hadn't really looked at Monoids, but then their utility fell out of the recent discussion about whether they should be called Monoids or ... whatever the other name was. And now I see them all over the place, and I'm a better person for it. Surely this is too much to be considered actual programming! cheers, Fraser. On Mon, Feb 16, 2009 at 10:40 PM, Duncan Coutts duncan.cou...@worc.ox.ac.uk wrote: On Mon, 2009-02-16 at 20:30 +0100, Fraser Wilson wrote: You must have missed the bit about congenitally lazy :-) Username requested ... See http://hackage.haskell.org/packages/accounts.html All you need to do is email Ross and ask. Duncan -- http://thewhitelion.org/mysister ___ 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] The wheather is ⊥
Is that really cold or really hot? On Sun, Feb 15, 2009 at 11:27 PM, Henk-Jan van Tuyl hjgt...@chello.nlwrote: The temperature is now NaN°: http://traviswalters.net/?p=58 -- Met vriendelijke groet, Henk-Jan van Tuyl -- http://functor.bamikanarie.com http://Van.Tuyl.eu/ -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why binding to existing widget toolkits doesn't make any sense
You know, I read the Fudgets thesis, and threw together an experiment which used Glade for layout and Haskell for semantics [1]. As somebody else noted, this isn't really a clean division, because of things like editable flags in the layout. The darcs repository has a couple of demo applications, there's also a Bridge game that doesn't quite work (not included), and I understand that Arrows would solve all my problems, but I still don't grok them, alas. What I found was that wiring the events through the application in a nice, functional way was quite tricky, but it was unclear whether this was just an API problem, or something more fundamental. The entire state seems to turn up in every connection between widgets (which really suggests that it's imperative with a veneer of declarative style, which of course it is). For example, you need a changed flag in the state of the text editor. This is updated by a signal from the text widget, and read by the main window (because it affects the title bar text), the File/New and File/Open menu items (need to put up a Save Changes? message box) and the main window destroy handler (same thing, but it also needs some way of cancelling the action). Unfortunately, the main window is at one end of the event chain, while the menu is all the way over on the other side. This leads to tricky composition, and widgets which pass the entire state to each other because there's one little bit of information they might need. A related issue is that the application is like a river, in which events flow from one end to the other. Send events back the other way is ugly. Some sort of blackboard design might work better. This conversation made me start thinking about replacing Glade with a Haskell layout language, but I still don't know how to solve the above problems. I should read the FRP papers again. cheers, Fraser. [1] http://thewhitelion.org/darcs/barrie On Mon, Feb 2, 2009 at 8:58 PM, John A. De Goes j...@n-brain.net wrote: The actual presentation and layout of widgets would be better handled by a DSL such as CSS (which is, in fact, declarative in nature), while event logic would be best handled purely in Haskell. Regards, John A. De Goes N-BRAIN, Inc. The Evolution of Collaboration http://www.n-brain.net|877-376-2724 x 101 On Feb 2, 2009, at 12:39 PM, Creighton Hogg wrote: 2009/1/29 Conal Elliott co...@conal.net: Hi Achim, I came to the same conclusion: I want to sweep aside these OO, imperative toolkits, and replace them with something genuinely functional, which for me means having a precise simple compositional (denotational) semantics. Something meaningful, formally tractable, and powefully compositional from the ground up. As long as we build on complex legacy libraries (Gtk, wxWidgets, Qt, OpenGL/GLUT, ...), we'll be struggling against (or worse yet, drawn into) their ad hoc mental models and system designs. As Meister Eckhart said, Only the hand that erases can write the true thing. I think working on a purely functional widget toolkit would actually be a really cool project. Do you have any ideas, though, on what should be the underlying primitives? The initial gut feeling I have is that one should just ignore any notion of actually displaying widgets instead focus on a clean algebra of how to 'add' widgets that relates the concepts of inheritance relative position. What I mean by inheritance, here, is how to direct a flow of 'events'. I don't necessarily mean events in the Reactive sense, because I think it'd be important to make the model completely independent of how time actual UI actions are handled. Any thoughts to throw in, here? Cheers, C ___ 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 -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to define Show [MyType] ?
1) They come from the show instance for String. Try putStrLn (t2 fleet) instead. pedant The show instance for Char. /pedant (I know you know this, I just have this weird fascination with the showList wart, although for the life of me I can't think of a better way of doing it) cheers, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] GHC on Fedora 10 - getMBlock: mmap: Permission denied
Hi all, Has anybody seen this? I thought it might be an SELinux thing, but then I wouldn't expect GHC or darcs to run. Audley is a fairly simple program in operating system feature terms, but I get the same error with anything I build myself. [EMAIL PROTECTED] audley]$ ./dist/build/audley/audley audley: internal error: getMBlock: mmap: Permission denied (GHC version 6.8.3 for i386_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Aborted [EMAIL PROTECTED] audley]$ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.8.3 [EMAIL PROTECTED] audley]$ cat /proc/version Linux version 2.6.27-0.352.rc7.git1.fc10.i686 ( [EMAIL PROTECTED]) (gcc version 4.3.2 20080917 (Red Hat 4.3.2-4) (GCC) ) #1 SMP Tue Sep 23 21:26:04 EDT 2008 [EMAIL PROTECTED] audley]$ cheers, Fraser. -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC on Fedora 10 - getMBlock: mmap: Permission denied
Why didn't that occur to me? I should get more sleep. Thanks for the tip. Now I know that it definitely is SELinux, a system I understand not at all, I presume the problem is in these context things ... ghc has system_u and bin_t, while audley has unconfined_u and file_t. Time to go poking about. The unconfined_u looks suspicious. cheers, Fraser. On Tue, Dec 2, 2008 at 3:48 PM, David Leimbach [EMAIL PROTECTED] wrote: Did you try turning off SELinux to check? 2008/12/2 Fraser Wilson [EMAIL PROTECTED] Hi all, Has anybody seen this? I thought it might be an SELinux thing, but then I wouldn't expect GHC or darcs to run. Audley is a fairly simple program in operating system feature terms, but I get the same error with anything I build myself. [EMAIL PROTECTED] audley]$ ./dist/build/audley/audley audley: internal error: getMBlock: mmap: Permission denied (GHC version 6.8.3 for i386_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Aborted [EMAIL PROTECTED] audley]$ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.8.3 [EMAIL PROTECTED] audley]$ cat /proc/version Linux version 2.6.27-0.352.rc7.git1.fc10.i686 ( [EMAIL PROTECTED]) (gcc version 4.3.2 20080917 (Red Hat 4.3.2-4) (GCC) ) #1 SMP Tue Sep 23 21:26:04 EDT 2008 [EMAIL PROTECTED] audley]$ cheers, Fraser. -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[2]: [Haskell-cafe] GHC on Fedora 10 - getMBlock: mmap: Permission denied
Thanks, Bulat, ticket #738 appears to be it. It was fixed in September, but I guess it hasn't made it to yum yet, although there's a work-around with permissions and so forth. cheers, Fraser. On Tue, Dec 2, 2008 at 4:42 PM, Bulat Ziganshin [EMAIL PROTECTED]wrote: Hello Fraser, Tuesday, December 2, 2008, 6:34:19 PM, you wrote: search in GHC tracker: afair there was some SELinux-releated report Why didn't that occur to me? I should get more sleep. Thanks for the tip. Now I know that it definitely is SELinux, a system I understand not at all, I presume the problem is in these context things ... ghc has system_u and bin_t, while audley has unconfined_u and file_t. Time to go poking about. The unconfined_u looks suspicious. cheers, Fraser. On Tue, Dec 2, 2008 at 3:48 PM, David Leimbach [EMAIL PROTECTED] wrote: Did you try turning off SELinux to check? 2008/12/2 Fraser Wilson [EMAIL PROTECTED] Hi all, Has anybody seen this? I thought it might be an SELinux thing, but then I wouldn't expect GHC or darcs to run. Audley is a fairly simple program in operating system feature terms, but I get the same error with anything I build myself. [EMAIL PROTECTED] audley]$ ./dist/build/audley/audley audley: internal error: getMBlock: mmap: Permission denied (GHC version 6.8.3 for i386_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Aborted [EMAIL PROTECTED] audley]$ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.8.3 [EMAIL PROTECTED] audley]$ cat /proc/version Linux version 2.6.27-0.352.rc7.git1.fc10.i686 ([EMAIL PROTECTED]) (gcc version 4.3.2 20080917 (Red Hat 4.3.2-4) (GCC) ) #1 SMP Tue Sep 23 21:26:04 EDT 2008 [EMAIL PROTECTED] audley]$ cheers, Fraser. -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Best regards, Bulatmailto:[EMAIL PROTECTED] -- http://thewhitelion.org/mysister ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Calling Haskell from other languages?
I had a proof of concept lying around a couple of years ago in which a big complicated Ada program called a big complicated Haskell program and vice versa. The tricky bit from memory was making it link, and satisfying their rumtime initialisation requirements. No explicit C was required I think. Fraser On 11 nov 2008, at 18:09, Colin Paul Adams [EMAIL PROTECTED] wrote: Jake == Jake Mcarthur [EMAIL PROTECTED] writes: Jake Actually, that's not the whole story. I didn't realize until Jake I sent it. There does exist good documentation for this, I Jake promise. Good. Let me know where it is when you track it down. The link you pointed me too doesn't seem to address my question directly. Also, it only talks about C. If I want to call Haskell (and I do, perhaps) from another garbage-collected language (Eiffel, in particular) using C as the mutually understood language, am I not going to run into big problems? -- Colin Adams Preston Lancashire ___ 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] if - then - else layout
I think you mean in a do. There is a proposal to fix this in Haskell' cheers, Fraser On Sep 25, 2008, at 6:59, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote: On 2008 Sep 25, at 0:47, leledumbo wrote: consider this partial program: if n5 then putStrLn big else putStrLn small this works fine in hugs, but in ghc I must change it to: if n5 then putStrLn big else putStrLn small Actually, this also works: if n 5 then putStrLn big else putStrLn small Except in a do, the else must be indented beyond the start of the if. I think Hugs is violating the Haskell98 layout rules. -- 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 university KF8NH ___ 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
[Haskell-cafe] Confused by instances
Hello, Haskellers, I feel like I'm missing something obvious, but here's some example code: module Instance where data Value = Value Integer class ValueClass a where fromValue :: Value - a instance ValueClass Bool where fromValue (Value n) = n /= 0 instance ValueClass String where fromValue (Value n) = show n instance (Num a) = ValueClass a where fromValue (Value n) = fromInteger n The Bool instance compiles fine. The String instance fails, and that would be because String is a synonym for [Char], and we can't create instances for those. There's a slight hack in the Prelude which allows you to define your own list show function, and that's exactly what gets done by Show Char, right? I'm sorry about calling it a hack but, well, it is. :) What I'm really confused by is the response to instance (Num a) = ValueClass a -- what I am trying to say is if a is an instance of Num, then can be an instance of ValueClass too, and here's how. But ghc says: Instance.hs:14:0: Illegal instance declaration for `ValueClass a' (All instance types must be of the form (T a1 ... an) where a1 ... an are distinct type *variables* Use -XFlexibleInstances if you want to disable this.) In the instance declaration for `ValueClass a' I don't understand why what I'm doing above is different from, for example, instance Show a = Show [a], or Monad m = MonadState s (StateT s m) ... I imagine that it's related to the fact that the difference between those two and what I have is that they have either the same class on each side of the =, or new type variables on the right. But I'm having trouble abstracting from that to the general rule. Any help would be greatly appreciated. In context, I'm attempting to wrap up different types inside a data type, and rather than extracting the value with getBoolean, getInteger, getString etc, I thought I would let type classes work for me, and just say fromValue instead. Is this silly? You can tell me, I won't be hurt. cheers, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Confused by instances
On Mon, Apr 28, 2008 at 10:50 PM, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote: The format is instance [context =] classname instance. Your classname is ValueClass. Your instance is a. a is not of the form (T a1 ... an). But neither is instance (Show a) = Show [a] ... *sound of penny dropping * Ah. Wood, trees, all that. Thanks! cheers, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Confused by instances
On Mon, Apr 28, 2008 at 11:33 PM, Luke Palmer [EMAIL PROTECTED] wrote: To answer your other question, no, there is no list show hack. Perhaps hack was a strong word. I'm not referring to type synonyms, but to the fact that Prelude's show class happens to have a special show function for lists, which happens to be handy when writing an instance for Show Char. I find the coupling here (between Show and a particular instance of Show, namely Show Char) to be disturbing -- Show should not (if you ask me) contain special machinery for specific instances. Not that I'll lose sleep over it, and of course the benefit (having pretty strings) far outweighs the philosophical cost. The showList function has always struck me as a bit of a wart though. cheers, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Confused by instances
On Mon, Apr 28, 2008 at 11:46 PM, Luke Palmer [EMAIL PROTECTED] wrote: 2008/4/28 Fraser Wilson [EMAIL PROTECTED]: what I am trying to say is if a is an instance of Num, then can be an instance of ValueClass too, and here's how. Oh, didn't answer this one. This is almost canned response, questions like this get asked weekly on this list. Thanks for the detailed response. In the end, I've just selected the types I'm really interested in, and added instances for those. It works a treat. cheers, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] export question (GHC.Handle)
On Thu, Apr 17, 2008 at 4:46 PM, Bertram Felgenhauer [EMAIL PROTECTED] wrote: Assuming you're writing a cabal package, you could separate the interface from the actual implementation: [..] HTH, Magic. Thanks a lot! cheers, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] export question (GHC.Handle)
On Thu, Apr 17, 2008 at 2:09 AM, Graham Fawcett [EMAIL PROTECTED] wrote: I notice in the source for GHC.Handle that certain functions (e.g. fdToHandle_stat) are in the export list, but are not actually exported (at least, it seems you cannot import them). What mechanism causes these functions to be hidden, and are they still accessible in some way? Good question. I often need to export a name to other modules within the hierarchy, but without making them visible outside it. I've solved this problem by giving them funky names and adding a comment, but is there a more structured way to do this? A quick google hasn't found one yet. cheers, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dynamic typing makes you more productive?
I find it interesting that change is equated with maintenance. I would say that maintenance is a very small subset of change. It's true that you can change a program in a dynamically typed language more easily, in the same way that changes are easier to make if you don't use source control and everybody shares the same source folder. Changes that improve things, however, are more tricky. And as you say, a large multiple developer, dynamically typed project sounds like a disaster. (Of course, I don't have to tell any of you this) cheers, Fraser. On Tue, Mar 18, 2008 at 5:41 PM, Justin Bailey [EMAIL PROTECTED] wrote: From a recent interview[1] with the guy leading Ruby development on .NET at Microsoft: You spend less time writing software than you spend maintaining software. Optimizing for writing software versus maintaining software is probably the wrong thing to do. Static typing makes it harder to maintain software because it's harder to change it. Two years ago I would have agreed with that statement. Now - no way. Make the compiler work for you. I've done a lot of Ruby development and I would never use it for a project of more than 3 or 4 people. It's an awesome language but I don't think it would scale to programming in the large. Any object can be modified at any time. Determining where a particular method comes from can be an exercise in Sherlockian deduction. Give an organization of 100 developers that much freedom and I can only imagine chaos would result. Justin [1] http://www.regdeveloper.co.uk/2008/03/17/ironruby_work_schedule/ ___ 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] Binary IO of a list of ints
(untested) mapM_ runPut data ? On Jan 24, 2008 12:14 PM, Jamie Love [EMAIL PROTECTED] wrote: Hi there I have a list of ints, with values between 0 and 255 and I need to print them out in little endian form to a file. I've been using Data.Binary for single values, e.g. runPut $ do put 'B' put (0 :: Int32) I'm wondering how I can go about writing a list of Ints out. My thought was to do something like: foldr (\x B.hPut output (runPut $ do put (x :: Word8))) data (where output is my file handle), but apart from giving me type errors, it seems a rather arduous way to do it. Could anyone suggest a better way to do this? -- Jamie Love Senior Consultant Aviarc Australia Mobile: +61 400 548 048 This message has been scanned for viruses and dangerous content by MailScanner and is believed to be clean. ___ 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] Trouble with function with two clauses
In head'', what is being compared to Nil? The guards of a function are a series of Boolean expressions; but in your example they are of type ConsCell a. The difference is that in a pattern, the structure of the argument is matched; in a guard, an arbitrary expression is evaluated. I have always found the Haskell report instructive in these cases; particularly the transformations into the core language -- in this case see section 4.4.3.2 (http://haskell.org/onlinereport/decls.html#sect4.4.3.2); this should make it clear why head'' is not valid Haskell. cheers, Fraser. Guards are really a series of Boolean equations, and the first that evaluates to true On Jan 9, 2008 7:15 PM, Fernando Rodriguez [EMAIL PROTECTED] wrote: Hi, I have the following type and function: data ConsCell a = Nil | Cons a (ConsCell a) deriving Show head' Nil = Nothing head' (Cons a _) = Just a Works fine, however, what's wrong with the following function? head'' | Nil = Nothing | Cons a _ = Just a Thanks! ___ 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] Filesystem access
I don't use Haskell on Windows, but if you go to http://www.haskell.org/ghc/docs/latest/html/libraries/index.html you'll find a package called System.Win32.File, which has these functions: *getFileAttributes* :: Stringhttp://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-Char.html#t%3AString- IOhttp://www.haskell.org/ghc/docs/latest/html/libraries/base/System-IO.html#t%3AIO FileAttributeOrFlaghttp://www.haskell.org/ghc/docs/latest/html/libraries/Win32/System-Win32-File.html#t%3AFileAttributeOrFlag *getFileInformationByHandle* :: HANDLEhttp://www.haskell.org/ghc/docs/latest/html/libraries/Win32/System-Win32-Types.html#t%3AHANDLE- IOhttp://www.haskell.org/ghc/docs/latest/html/libraries/base/System-IO.html#t%3AIO BY_HANDLE_FILE_INFORMATIONhttp://www.haskell.org/ghc/docs/latest/html/libraries/Win32/System-Win32-File.html#t%3ABY_HANDLE_FILE_INFORMATION The first has all sorts of attributes in it, the second has a field for length. Maybe these will do what you want. cheers, Fraser. On 6/21/07, Andrew Coppin [EMAIL PROTECTED] wrote: Andrea Rossato wrote: On Thu, Jun 21, 2007 at 09:19:51PM +0100, Andrew Coppin wrote: OK, a few questions... 1. Is there *any* way to determine how large a file is *without* opening it? The only library function I can find to do with file sizes is hFileSize; obviously this only works for files that you have permission to open! System.Posix.Files fileSize Does that *work* on Windoze? Wait, hang on a sec... No, it doesn't. The module doesn't even exist. (I was half-expecting it might work. GHC does currently run in a Unix emulator...) 2. Is there any way to discover Windoze-style attributes for files? (Read-only, archive, system, hidden, et al.) The module before, if I understand correctlu. No, AFAIK the archive attribute doesn't even exist on POSIX. It's a Windoze-specific thang. ___ 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] Records (was Re: [Haskell] Improvements to GHC)
On 11/17/05, Greg Woodhouse [EMAIL PROTECTED] wrote:
Isn't there a potential for confusion with function composition (f . g)?
Perhaps, but I always have spaces on either side when it's function composition. Isn't there already an ambiguity?
-- I bet there's a quicker way to do this ...
module M where data M a = M a deriving (Show)
data T a = T a deriving (Show)
module M.T where f = (+1)
import M
import qualified M.T
f = (*2)
v1 = M . T . f $ 5
v2 = M.T.f $ 5
main = do { print v1; print v2; return () }
Fraser.
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Re: [Haskell-cafe] Families of type classes
On 11/6/05, Klaus Ostermann [EMAIL PROTECTED] wrote: instance Node Person where isConnectedTo g n (p1,p2) = (p1 == n) || (p2 == n) At this point, isConnectedTo knows nothing about the third argument except that it is an edge, and there's no reason to think that an Edge is a tuple. All you can say is that there are two functions, n1 and n2, which extract the nodes of the edge. Use those instead, for example isConnectedTo g n p = n == n1 p || n == n2 p Couldn't match the rigid variable `e' against `(a, b)'`e' is bound by the type signature for `isConnectedTo' Expected type: eInferred type: (a, b)When checking the pattern: (p1, p2)In the definition of `isConnectedTo':isConnectedTo g n (p1, p2) = (p1 == n) || (p2 == n) Hopefully this error makes more sense now. It's saying that it expected something of type 'e', but it found a tuple. regards, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Interactive Haskell and hs-plugins
Hi there, I would like to use evaluate arbitrary expressions in the context of a mixed-language (Ada, Haskell and about twelve lines of C glue) applications. Is it possible to use dynload from hs-plugins to load a module that references symbols in the loading program? For example, the application contains a Haskell module that looks a bit like this: module TestKeys.NamedObject where tt :: Int tt = 2 I want the application to be able to offer the following sort of interaction: haskell tt 2 haskell But what actually happens is this: haskell tt test_haskell3: /tmp/MDnum15633.o: unknown symbol `TestKeysziNamedObject_tt_closure' test_haskell3: user error (resolveObjs failed with False) Compiling Haskell code in advance works (i.e. if I create and compile a module that evalutes tt and link it in, everything runs fine). This is how I try to evaluate the _expression_: evaluate :: String - IO () evaluate = return () evaluate e = do writeFile temp.hs fileContents status - makeWith LeanderStub.hs temp.hs [-c] case status of MakeSuccess code path - loadAndEval path MakeFailure error - print error where fileContents = module Temp where\n\ \ result = ++ e ++ \n loadAndEval :: FilePath - IO () loadAndEval path = do mv - dynload path [] [] result case mv of LoadFailure msg - print msg LoadSuccess _ v - putStrLn v LeanderStub.hs is a module containing the necessary imports for the _expression_ to evaluate in the right context. I was hoping that passing -c to makeWith would create an object file whose missing dependencies would be resolved when it was loaded into an application which contained them. Is this a dumb expectation? The alternative -- linking to the entire application for each _expression_ evaluated -- seems a bit over the top, and I can't see how state would be maintained. I originally used unsafeEval_, but this has the same problem. I can't help but think that this must have been done before. Any advice? If you know Guile, then the equivalent of gh_repl is what I'm really after. cheers, Fraser. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
