Re: Haskell verification Tools?
On Sun 10 Oct, Messenger wrote: Does anyone know if there exist theorem proving or formal verfication tools for Haskell? I don't know about Haskell, but the Clean developers have such a tool for Clean. Any theorems which are true for Clean should also be true for Haskell, I imagine. You can get it here.. http://www.cs.kun.nl/~maartenm/CleanProverSystem/ Regards -- Adrian Hey
re: The Haskell mailing list
| I also agree with Simon that simply making this a moderated list is | not the solution. Perhaps splitting is best. How about | | haskell-info | haskell-talk | | where info carries *brief* announcements, requests for information | and responses to such requests, and talk carries anything and | everything else appropriate to a Haskell list. I like that proposal, Ralf
Re: OO in Haskell
On Mon 11 Oct, Lars Lundgren wrote: I'm sure a lot of poeple have gotten this wrong. I would be surprised if not all the experienced haskellers has this view though. Probably so, but this view seems in complete contradiction to that of the Clean world. So I'm still confused :-) Regards -- Adrian Hey
Re: Wishlist: MixFix syntax
This is a repost of an earlier post from before there was an explicit wishlist so it might make it onto the wishlist. The idea was inspired by OBJs syntax. Something similar is also available in Isabelle. I always liked the possibility to declare infix operators, may we extend this to mixfix? E.g. Please see my note _Macros and Preprocessing in Haskell_, which makes a proposal for just this feature. http://www.cl.cam.ac.uk/users/kw217/research/papers.html Enjoy! --KW 8-) -- : Keith Wansbrough, MSc, BSc(Hons) (Auckland) : : PhD Student, Computer Laboratory, University of Cambridge, England. : : (and recently of the University of Glasgow, Scotland. [] ) : : Native of Antipodean Auckland, New Zealand: 174d47' E, 36d55' S.: : http://www.cl.cam.ac.uk/users/kw217/ mailto:[EMAIL PROTECTED] : :-:
Re: OO in Haskell
On Mon, 11 Oct 1999, Adrian Hey wrote: On Mon 11 Oct, Lars Lundgren wrote: I'm sure a lot of poeple have gotten this wrong. I would be surprised if not all the experienced haskellers has this view though. Probably so, but this view seems in complete contradiction to that of the Clean world. So I'm still confused :-) I just took a glance at Clean. (Glanced through "The Ins and Outs of Clean I/O" by Peter Achten and Rinus Plasmeijer.) I think their solution with unique types is really neat. One downside may be that they have made the type system more complex since it has to handle all the uniqness tags. They deal with side effects (IO) by tagging the values with * and calling them unique. Haskell deals with side effects (IO) by using an abstract data type IO a which denotes an action [with clean type *World - (a,*World) ]. In both cases, the compiler is notified that it is not ok to change order of evaluation. In the Related work section, they mention Monadic IO and writes "To our knowledge combining monads of different type is a rather tedious task..." I'm reluctant to say that I agree. I have written a few programs using monad transformers and while everything works in principle, it is, well - tedious... I also do not like the tendency to put more things in the IO monad (I'm thinking about the extensions with IORef). I like stToIO better, but somehow it still feels like a hack. Maybe some library support for monad transformers and maybe even some syntactig sugar would do the trick. They also wrote "[The monadic IO approach] over determines order of evaluation". I'm a bit puzzled about that statement. Is it true? Comments anyone? /Lars L
Re: Haskell mailing list
I, like many others, are about to get off the Haskell mailing list unless a way is found to cut down the traffic immediately. I think we could go far with the current list if people would only exercise some judgement by not posting every reply to the whole list. Arvind
Re: Haskell mailing list
Ralf Muschall writes: [EMAIL PROTECTED] wrote: set up comp.lang.haskell? I agree with the above. This is IMHO the best solution for a lot of reasons: I disagree. One major reason is the spam problem: a post to a newsgroup essentially guarantees putting your name on a spam mailing list, and receiving large quantities of Make Money Fast postings. 2. The decision problem (high volume list without the important people or having to hesitate before every article) goes away. Many "important people" have a policy of no longer reading Usenet. 3. There is no human work needed to maintain a group once it exists. This is just as true for a mailing list as for a newsgroup. Also, news is not distributed everywhere, and even if news is available there's no guarantee everyone will be able to convince their sysadmin to accept the new group c.l.h. Email is surely available everywhere. Technical question: Are there people *writing* to this list without being subscribed? I very often see other people answering with header lines like "To: [EMAIL PROTECTED], [EMAIL PROTECTED]" The first of these addresses would be redundant if there were no such participants. It's polite to cc: the author. This ensures they get the message first (before everyone else), and that it ends up in their inbox rather than just in amongst 345 other messages in their Haskell folder[1]. It's also easier in most mail clients to just click "reply all"; "reply to author" doesn't send the message to the list also. Ralf HTH. --KW 8-) [1] Actual count in my folder after two weeks away (!!).
Re: OO in Haskell
On Fri, 8 Oct 1999, Adrian Hey wrote: On Fri 08 Oct, Lars Lundgren wrote: A value (IO a) *denotes* a program possibly interacting with the world. *That* program is of course not referentially transparent. A haskell program generating an (IO a) on the other hand *is* referetially transparent. So a value of type (IO a) is _not_ a function, if I understand you correctly. From haskell point of view, it's a value, end of story. The value denotes an action possibly doing IO. When this action is executed, it will probably have side effects (thus, it is not a pure function), after all thats the sole purpose of IO. I think this is really the correct interpretation, but I'm not sure if there's any real enthusiasm for this view in the FP community at large. (When I suggested a similar approach on another list it didn't seem to go down to well.) I'm sure a lot of poeple have gotten this wrong. I would be surprised if not all the experienced haskellers has this view though. Also, the fact that the machine which executes values of type (IO a) is not regarded as part of Haskell is also not widely understood I think. (Well, at least I had not understood this before.) I agree with this. /Lars L
Re: Haskell mailing list
Keith Wansbrough wrote: [snip] I disagree. One major reason is the spam problem: a post to a newsgroup essentially guarantees putting your name on a spam mailing list, and receiving large quantities of Make Money Fast postings. I normally spam-proof my e-mail address on newsgroups for this reason. Though I'm not sure it's such a big problem as it has been; I sent a few unprotected usenet postings on Thursday and have yet to get any spam back from them. Also I think it likely that someone who spammed me a few months ago got my address from the Haskell archives. [snip] It's polite to cc: the author. I don't normally because getting two copies of the same message is a bore. In general I think Usenet is superior for common discussions, as that is what it is designed for. For example: 1) I don't have go through Usenet messages deciding which to delete, because I know they are all archived anyway. If I get bored with a thread I just K it and I never have to think about it again. 2) I have to assume that e-mail sent to me personally requires a rapid response. So I have to go to the trouble of opening Netscape whenever I get an e-mail. It is irritating when the e-mail is concerned with some Haskell issue which doesn't interest me. I use Netscape 4.6 for e-mail and Usenet. Please don't tell me how wonderful my life would be if I could be bothered to switch to procmail, emacs news/mail and so on, as I can't be bothered.
Re: Xtract with hugs and Haskell implementation inconsistency
| -From ParseSTXml.hs
| #define PARSEARG(tok) P (\st inp - case inp of { \
| ((p,tok n):ts) - [(n,st,ts)]; \
| ts - [] } )
| name :: Parser SymTab Token Name
| name = PARSEARG(TokName)
|
| string, freetext :: Parser SymTab Token String
| string = PARSEARG(TokName)
| freetext = PARSEARG(TokFreeText)
| ---
|
| Think ABSTRACTIONS and MONADS. Hows about
|
| name :: Parser SymTabs Token Name
| name = do
| (_,TokName n) - item
| return n
| string :: Parser SymTabs Token String
| string = do
| (_,TokName n) - item
| return n
| freetext :: Parser SymTabs Token String
| freetext = do
| (_,TokFreeText n) - item
| return n
Looks good. Now why didn't I think of that? I suppose I'm not yet
used to the fact that a stmt in a do-block can fail cleanly (i.e.
pattern-binding failure leads to a call of `fail', which is this case
is conveniently []).
| Neat, clean and Haskell 98.
Indeed. Thanks.
Regards,
Malcolm
Re: Haskell mailing list
Would it be possible to have both the current mailing list and a Haskell newsgroup? If postings to each were automatically replicated on the other, then each reader could take her choice of which one to follow. --Ham -- Hamilton Richards Jr.Department of Computer Sciences Senior Lecturer Mail Code C0500 512-471-9525 The University of Texas at Austin SHC 434 Austin, Texas 78712-1188 [EMAIL PROTECTED] --
RE: Haskell mailing list
I would be very sorry to see the Haskell mailing list go to a news group as I have no way of reading news groups. Bruce Haxton [EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [SMTP:[EMAIL PROTECTED]] Sent: 08 October 1999 11:19 To: S.J.Thompson Cc: [EMAIL PROTECTED] Subject: Haskell mailing list S.J.Thompson writes: I agree with Simon's observations, and would suggest a third option: why not set up comp.lang.haskell? I agree with the above. The established procedure for creation of a news group is documented in the news.announce.newgroups FAQ available at: [EMAIL PROTECTED]:/pub/rtfm/usenet/news.announce.newgroups The first step would be to post a Request For Discussion (RFD) to news.announce.newgroups. Instructions and a template for doing this can be found in "How_to_Format_and_Submit_a_New_Group_Proposal" at the above ftp site. Help with the news group creation process can be obtained from [EMAIL PROTECTED] . Perhaps some suitably illustrious person (e.g. Simon ?) would like to post an RFD for comp.lang.haskell Tim
Unicode (was RE: Reverse composition)
Brian Boutel writes: [...] If the supply of suitable Ascii symbols seems inadequate, remember that Haskell uses Unicode. There is no reason to limit symbols to those in the Ascii set. While we're on the subject, I suggest Unicode as a Hugs/GHC wish list item. In particular, I'd like to use the familiar symbols for union, intersection, and subset, without resorting to Ascii art, please. Regards, Tom
Question on graphics
"Ronald" == Ronald J Legere [EMAIL PROTECTED] writes: I am wondering however if there is anykind of small package to enable me to make simple plots (of functions for example).. This is for windows (98) machine, so I cant use Gif Writer, which seems sort of how to do it on unix machines I don't know. If there isn't I think there is a postscript driver of some kind described in The functional approach to programming by Cousineau and Mauny CUP 98. (In Caml, but maybe it is cribbable.) Peter
Re: Haskell mailing list
In article ifado.list.haskell/[EMAIL PROTECTED], Keith Wansbrough [EMAIL PROTECTED] wrote: Ralf Muschall writes: [EMAIL PROTECTED] wrote: set up comp.lang.haskell? I agree with the above. This is IMHO the best solution for a lot of reasons: I disagree. One major reason is the spam problem: a post to a newsgroup essentially guarantees putting your name on a spam mailing list, and receiving large quantities of Make Money Fast postings. How do you come to think that mailing lists do not receive spam? Mailing lists are evil except for a very limited (or restricted) public ( 100 p ersons). 2. The decision problem (high volume list without the important people or having to hesitate before every article) goes away. Many "important people" have a policy of no longer reading Usenet. A lot of important people are in error otherways also. I redirect any mailing list I happen to subscribe to into a local newsgroup. I am glad of any such local group disappearing by converting the mail list into a regular news group. This happened in comp.compilers.lcc, e.g. BTW: The correct thing to do about SPAM is neither to leave Usenet nor to try antispammed adresses (this is just to promote evolution of better (worse) spammers). Spammers have to be prosecuted, legally and socially.
