Re: [Haskell-cafe] IO trouble
Xiao-Yong Jin schrieb: Lauri Alanko l...@iki.fi writes: On Tue, May 12, 2009 at 04:59:36PM -0400, Xiao-Yong Jin wrote: f :: a - b g :: (a - b) - c - d gf :: c - d gf = g f Now I want to handle exceptions in f and redefine f as in f' f' :: a - IO (Either e b) So my question is how to define gf' now to use f' instead of f? gf' :: c - IO (Either e d) Use Control.Monad.Error.ErrorT, it's exactly for this. You have to monadize g to be able to pass f' as an argument to it. f' :: a - ErrorT e IO b g' :: Monad m = (a - m b) - c - m d gf' :: c - ErrorT e IO d gf' = g' f' So there is no way to do it without monadize g to g', is it? Big trouble, sigh. Sure, but I'm afraid that gets more complicated. Btw. you can also use ExceptionalT and Exceptional from explicit-exception package, which does not require a constraint on the exception type. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [darcs-users] [Haskell-cafe] Darcs as undo/redo system?
Am Mittwoch, 13. Mai 2009 02:55 schrieb Trent W. Buck: Wolfgang Jeltsch g9ks1...@acme.softbase.org writes: Am Freitag, 8. Mai 2009 18:43 schrieb Jason Dagit: If you wanted to work on this, I would encourage you to read more about patch theory[1,2,3,4] and also try out libdarcs[5]. Is libdarcs the same as the darcs library package on Hackage (which exports the darcs API)? The Darcs package (both on Hackage and elsewhere) builds two things: the darcs(1) binary, and libHSdarcs. The latter is what Jason was referring to. Note that currently it just exposes all our internal functions, rather than providing a coherent (or stable!) API. I know. My students, who worked on a darcs GUI frontend, already experienced this. ;-) Best wishes, Wolfgang ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Removing mtl from the Haskell Platform
Am Mittwoch, 13. Mai 2009 01:03 schrieb rocon...@theorem.ca: I wanted to pass this idea around the cafe to get some thoughts before submitting a trac on this topic. I'd like to see the mtl removed from the Haskell Platform. The mtl was a tremendous step forward when it was developed. However, we have learned a few things about monad transformers since the development of the mtl, and it is time that we moved forward. There are at least 3 significant problem with the mtl. 1) `pass' should not be a member functions of the MonadWriter class. It is my understanding that there is no `MonadWriter w m = MonadWriter w (ContT s m)' instance because the `pass' function cannot be implemented. I'm also highly suspicious of some other methods too (I'm looking at you `local'). 2) The `StateT s (Cont r a)' instance of callCC is wrong. The paper on modular monad transformers http://www.cs.nott.ac.uk/~mjj/pubs/mmt/mmt.pdf describes why this is wrong. 3) I am told by many people that the order of the state and value pair in `State' is backwards. Actually, I'm not entirely sure what the issue is here, but I trust the people who say this. 4) The identifiers State and StateT are flawed. Something of value State s a doesn’t denote a state but a state transformer or however you want to name it. Best wishes, Wolfgang ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [ANNOUNCE] Bindings for libguestfs
On Wed, May 13, 2009 at 11:15:24PM +1000, Peter Gammie wrote: Hope this helps! Thanks for your honest helpful answer. I think I will try again at compiling c2hs so I can look at the code that it generates. Rich. -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://et.redhat.com/~rjones/virt-df/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Removing mtl from the Haskell Platform
On Thu, May 14, 2009 at 10:14, Wolfgang Jeltsch g9ks1...@acme.softbase.org wrote: 4) The identifiers State and StateT are flawed. Something of value State s a doesn’t denote a state but a state transformer or however you want to name it. A state monad, i.e. a monad containing a state? If you use it in a sentence in that way, the name State makes sense. StateTransformer or something like that would lead to much confusion with the state transformer transformer that is currently called StateT. I don't really see a good alternative to the name State, and a good thing about it is that it is short. Oh, bikesheds ought to be brown, of course. Cheers, Thomas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functional Reactive Web Application Framework?
Yes, I didn't realise that until Arjun mentioned that. I'm going to try to find some time to look more closely at Flapjax... -Rob On Wed, May 13, 2009 at 11:30 PM, Don Stewart d...@galois.com wrote: wrwills: The only web-oriented frp framework that I know of is Flapjax http://www.flapjax-lang.org/ Flapjax is javascript so possibly there could be a way to integrate it into Haskell using HJavascript? Maybe it could even be integrated into Happstack? I'm also quite new to Haskell. Isn't the flapjax compiler implemented in Haskell? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Structural sharing in haskell data structures?
Wren, It's not true for Java either. The idea of cheap throw-away objects isn't foreign for modern JVMs. GC favors short-lived immutable objects since: - all collectors are generational; - GC cycle duration is proportional to the size of live objects, not the heap size; - object allocation is _very_ cheap, even in parallel; Moreover, many advanced techniques are used in JVM GCs: - there are parallel concurrent collectors; - adaptive ergonomics (e.g. heap resizing, according to some goals on collection duration); There are problems with functional languages on top of JVM, but GC isn't among them. If you are interested in current work, you may look at mlvm project [1]. -- vi [1] http://openjdk.java.net/projects/mlvm/ On Thu, May 14, 2009 at 2:58 AM, wren ng thornton w...@freegeek.org wrote: Jan-Willem Maessen wrote: I wanted to clear up one misconception here... wren ng thornton wrote: In heavily GCed languages like Haskell allocation and collection is cheap, so we don't mind too much; but in Java and the like, both allocation and collection are expensive so the idea of cheap throwaway objects is foreign. Not true! I was speaking of Java, not Clojure. I believe the costs in Java are well documented, though I don't know enough about the JVM to know where the blame belongs. (All I know of Clojure is that it's a Lisp-like on the JVM :) If you look at the internals of Clojure, you'll discover they're using trees with *very* wide fanout (eg fanout-64 leaf trees for lists). Why? Because it's so cheap to allocate and GC these structures! By using shallow-but-wide trees we reduce the cost of indexing and accessing list elements. I suspect you'd still be hard-pressed to support this kind of allocation behavior in any of the present Haskell implementations, and Haskell implementations of the same kinds of structures have limited fanout to 2-4 elements or so. I was under the impression that the reason datastructures in Haskell tend to be limited to 4-fanout had more to do with the cleanliness of the implementations--- pattern matching on 64-wide cells is quite ugly, as is dealing with the proliferation of corner cases for complex structures like finger trees, patricia trees, etc. The use of view patterns could clean this up significantly. On the other hand, we do have things like lazy ByteStrings and UVector which do have wide fanouts. -- Live well, ~wren ___ 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] Fun with type functions
Friends Ken, Oleg, and I have been working on a tutorial paper about type families (aka associated data types, or type functions). It's in draft at the moment, and we'd really appreciate feedback that would help us improve it. Here it is: http://haskell.org/haskellwiki/Simonpj/Talk:FunWithTypeFuns Thank you! Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] haskellnet
Hello, Yesterday I found myself wanting to clear out a spam-ridden pop account without downloading all the messages. Rather than just using Python's poplib, I thought I might look for a haskell solution and came across Haskellnet: http://darcs.haskell.org/SoC/haskellnet/ I ended up spending much of the afternoon getting it to compile and much of last night trying to get the pop library to actually work (the 'strip' method produced exceptions). It was a good learning experience (this was helpful: http://donsbot.wordpress.com/2007/11/14/no-more-exceptions-debugging-haskell-code-with-ghci/). I'm writing here because I'm wondering whether it would be worthwhile putting it up on hackage? From searching this list, there seem to have been a few times when people have stumbled across it but got frustrated when it didn't compile. If so, what's the protocol? Is the original author, Jun Mukai, still around? Thanks, Rob ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Structural sharing in haskell data structures?
On May 13, 2009, at 6:58 PM, wren ng thornton wrote: Jan-Willem Maessen wrote: I wanted to clear up one misconception here... wren ng thornton wrote: In heavily GCed languages like Haskell allocation and collection is cheap, so we don't mind too much; but in Java and the like, both allocation and collection are expensive so the idea of cheap throwaway objects is foreign. Not true! I was speaking of Java, not Clojure. I believe the costs in Java are well documented, though I don't know enough about the JVM to know where the blame belongs. (All I know of Clojure is that it's a Lisp- like on the JVM :) I think you're missing the point here: the code I refer to below *is in Java* and is running on a standard JVM; the costs you refer to simply don't exist! As Vladimir Ivanov points out, and as Rich Hickey is happy to observe in his talks on Clojure, the JVM handles allocation-intensive garbage-intensive programs very well. If you look at the internals of Clojure, you'll discover they're using trees with *very* wide fanout (eg fanout-64 leaf trees for lists). Why? Because it's so cheap to allocate and GC these structures! By using shallow-but-wide trees we reduce the cost of indexing and accessing list elements. I suspect you'd still be hard-pressed to support this kind of allocation behavior in any of the present Haskell implementations, and Haskell implementations of the same kinds of structures have limited fanout to 2-4 elements or so. I was under the impression that the reason datastructures in Haskell tend to be limited to 4-fanout had more to do with the cleanliness of the implementations--- pattern matching on 64-wide cells is quite ugly, as is dealing with the proliferation of corner cases for complex structures like finger trees, patricia trees, etc. The use of view patterns could clean this up significantly. On the other hand, we do have things like lazy ByteStrings and UVector which do have wide fanouts. Hmm, I think neither of the data structures you name actually support both O(lg n) indexing and O(lg n) cons or append. That said, your point is well taken, so let's instead state it as a challenge: Can you, oh Haskellers, implement a fast, wide-fanout (say = 8) tree- based sequence implementation in Haskell, which supports at-least-log- time indexing and at-least-log-time cons with a large base for the logarithm? Can you do it without turning off array bounds checking (either by using unsafe operations or low-level peeking and poking) and without using an algebraic data type with O(f) constructors for fanout of f? You can turn off bounds checks if your program encodes static guarantees that indices cannot be out of bounds (there are a couple of libraries to do this). The spirit here is Work in Haskell with safe operations and no FFI except through safe libraries, but otherwise use any extensions you like. I actually think this *is* doable, but it touches a few areas where Haskell doesn't presently do well (the bounds checking in particular is a challenge). I threw in the bounds checking when I realized that in fact the equivalent Java code is always bounds checked, and these bounds checks are then optimized away where possible. Actually, I'd *love* to see an *in*efficient solution to eliminating as many bounds checks as possible! -Jan -- Live well, ~wren ___ 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] haskellnet
Hi Email the original author, if you can. Ideally work with them to upload a working version to hackage. If they're not interested hopefully they'll make you the new maintainer. If you can't contact them, just upload a new version anyway - as long as it's done for the benefit of the community and not with malicious intent, everyone is happy. And please do make sure you upload something working, I imagine this will be very useful to lots of people! Thanks for your efforts Neil On Thu, May 14, 2009 at 12:51 PM, Robert Wills wrwi...@gmail.com wrote: Hello, Yesterday I found myself wanting to clear out a spam-ridden pop account without downloading all the messages. Rather than just using Python's poplib, I thought I might look for a haskell solution and came across Haskellnet: http://darcs.haskell.org/SoC/haskellnet/ I ended up spending much of the afternoon getting it to compile and much of last night trying to get the pop library to actually work (the 'strip' method produced exceptions). It was a good learning experience (this was helpful: http://donsbot.wordpress.com/2007/11/14/no-more-exceptions-debugging-haskell-code-with-ghci/). I'm writing here because I'm wondering whether it would be worthwhile putting it up on hackage? From searching this list, there seem to have been a few times when people have stumbled across it but got frustrated when it didn't compile. If so, what's the protocol? Is the original author, Jun Mukai, still around? Thanks, Rob ___ 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] Structural sharing in haskell data structures?
On Thu, 2009-05-14 at 09:03 -0400, Jan-Willem Maessen wrote: Hmm, I think neither of the data structures you name actually support both O(lg n) indexing and O(lg n) cons or append. That said, your point is well taken, so let's instead state it as a challenge: Can you, oh Haskellers, implement a fast, wide-fanout (say = 8) tree- based sequence implementation in Haskell, which supports at-least-log- time indexing and at-least-log-time cons with a large base for the logarithm? Can you do it without turning off array bounds checking (either by using unsafe operations or low-level peeking and poking) and without using an algebraic data type with O(f) constructors for fanout of f? You can turn off bounds checks if your program encodes static guarantees that indices cannot be out of bounds (there are a couple of libraries to do this). Can we motivate the restriction of not using multiple constructors? If we're only talking about a fanout of 8 then it doesn't look like a problem. It sounds like you're really asking for an array but without wanting to say so explicitly. Perhaps you should ask for a variable fanout or a fanout of something bigger like 32 (and presumably these requirements could be justified too?). Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Structural sharing in haskell data structures?
On May 14, 2009, at 10:17 AM, Duncan Coutts wrote: On Thu, 2009-05-14 at 09:03 -0400, Jan-Willem Maessen wrote: Hmm, I think neither of the data structures you name actually support both O(lg n) indexing and O(lg n) cons or append. That said, your point is well taken, so let's instead state it as a challenge: Can you, oh Haskellers, implement a fast, wide-fanout (say = 8) tree- based sequence implementation in Haskell, which supports at-least- log- time indexing and at-least-log-time cons with a large base for the logarithm? Can you do it without turning off array bounds checking (either by using unsafe operations or low-level peeking and poking) and without using an algebraic data type with O(f) constructors for fanout of f? You can turn off bounds checks if your program encodes static guarantees that indices cannot be out of bounds (there are a couple of libraries to do this). Can we motivate the restriction of not using multiple constructors? If we're only talking about a fanout of 8 then it doesn't look like a problem. I actually expect this will cause some fairly nasty code bloat, but I'm happy to be proven wrong. :-) It sounds like you're really asking for an array but without wanting to say so explicitly. Perhaps you should ask for a variable fanout or a fanout of something bigger like 32 (and presumably these requirements could be justified too?). Wide fanout seems fair. -Jan Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] PhD position in Nottingham
PhD position in Type Theory at Nottingham - A new PhD position is available in the Functional Programming Laboratory at the University of Nottingham. The topic of research for the project is Programming and Reasoning with Infinite Structures: it consists in the theoretical study and development of software tools for coinductive types and structured corecursion. The candidate must be a UK resident with an excellent degree in Computer Science or Mathematics at MSc (preferred) or BSc level (first class or equivalent). The applicant should have a good background in mathematical logic, theoretical computer science or functional programming. (S)he should be interested doing research in type theory, constructive mathematics, category theory and foundations of formal reasoning. We offer: PhD place with living expenses (standard UK level) for 3 years. The grants also provide laptops and travel expenses for conference and workshop visits. Nottingham University provides a vibrant research environment in the Functional Programming Laboratory. Deadline for applications: 20 June 2009. Send a cover letter and your CV to Venanzio Capretta (v...@cs.nott.ac.uk). Please contact me for any additional information that you need. This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Performance Problem with Typeable
Interesting. Would anyone care to make a Trac ticket for this (with perf bug as the ticket kind), and (if at all possible) do some investigation to see what is going on? Many thanks Simon | -Original Message- | From: haskell-cafe-boun...@haskell.org [mailto:haskell-cafe-boun...@haskell.org] On | Behalf Of Michael D. Adams | Sent: 13 May 2009 22:57 | To: Haskell Cafe | Subject: [Haskell-cafe] Performance Problem with Typeable | | I'm not sure where this should be reported, but I think I've found a | significant asymptotic performance problem with Data.Typeable. In the | attached code, sum2 runs much slower than either sum1 or sum3. It | should be linear but it seems to slow down quadratically (i.e. | doubling len quadruples the time for sum2). Here is an example run: | | $ ghc --make -O3 CastSpeed.hs | $ ./CastSpeed 2 | gsum1 | Result: 20001 | Time(sec): 7.999e-3 | Result: 20001 | Time(sec): 0.0 | Result: 20001 | Time(sec): 1.0e-3 | | gsum2 | Result: 20001 | Time(sec): 1.483774 | Result: 20001 | Time(sec): 1.46 | Result: 20001 | Time(sec): 1.523768 | | gsum3 | Result: 20001 | Time(sec): 5.999e-3 | Result: 20001 | Time(sec): 0.0 | Result: 20001 | Time(sec): 0.0 | | The only difference between sum1 and sum2 is that sum2 wraps a | singleton list around each element (i.e. the cast is to [Int] instead | of Int). The only difference between sum2 and sum3 is that sum3 uses | an unchecked cast (unsafeCoerce) instead of a checked cast. This | problem seems to crop up only for those types which are made up of a | type constructor applied to an argument (e.g. [] applied to Int). | | Because of sum3 runs fast, I suspect that something is going wrong | with the typeOf call in a checked cast, and because sum1 runs fast I | suspect that what is going wrong is the call to appKey that is called | from mkAppTy that is called from typeOfDefault that is called from the | Typeable instance for [Int] (i.e. instance (Typeable1 s, Typeable a) | = Typeable (s a)). This is a bit of speculation and I don't have | hard evidence for that being the source of the problems, but tests | that I have run (not listed here) are strongly suggestive of appKey | being the culprit. | | Michael D. Adams | mdmko...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Developing 3 dimensional interactive environments/functional objects
Thanks guys, I appreciate the feedback. I'll update the mailing list with progress in my endeavors in the best way. With best wishes, Paul Original Message Subject: Re: [Haskell-cafe] Developing 3 dimensional interactive environments/functional objects From: Peter Verswyvelen bugf...@gmail.com Date: Tue, May 12, 2009 3:24 pm To: Don Stewart d...@galois.com Cc: paulfran...@friendbliss.com, haskell-cafe@haskell.org You might want to contact the author of RogueStar GLhttp://roguestar.downstairspeople.org/ On Tue, May 12, 2009 at 5:21 PM, Don Stewart d...@galois.com wrote: paulfrancis: Does any programmer on this mailing list have experience with developing 3 dimensional interactive environments/functional objects within them, au Second Life? Is Haskell useful for such an endeavor? Mm.. Anygmahttp://www.anygma.com/JobOfferA.html gamr7http://www.gamr7.com/ Both use Haskell to some extent. ___ 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] Structural sharing in haskell data structures?
On May 14, 2009, at 11:01 AM, Dan Doel wrote: On Thursday 14 May 2009 9:03:30 am Jan-Willem Maessen wrote: Hmm, I think neither of the data structures you name actually support both O(lg n) indexing and O(lg n) cons or append. That said, your point is well taken, so let's instead state it as a challenge: Data.Sequence has O(log n) index, concatenation, update, take, drop and splitAt, and O(1) cons, snoc, and viewing at both ends, according to the documentation. Yes. But large sequences end up being quite deep. Can a wide-fanout version be made that is actually faster? Note that the effective fanout of Hinze's finger trees is approximately e; consider effective fanouts of e^2 to e^4 (which may require substantially higher maximum fanout). -Jan -- Dan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Structural sharing in haskell data structures?
On Thursday 14 May 2009 9:03:30 am Jan-Willem Maessen wrote: Hmm, I think neither of the data structures you name actually support both O(lg n) indexing and O(lg n) cons or append. That said, your point is well taken, so let's instead state it as a challenge: Data.Sequence has O(log n) index, concatenation, update, take, drop and splitAt, and O(1) cons, snoc, and viewing at both ends, according to the documentation. -- Dan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] hsffig and duplicate typedef declarations
Dean, I am not sure how HSFFIG would deal with duplicate typedefs (I'm afraid you get error from gcc when processing hsc2hs output). In case you haven't seen this, I put a repo for HSFFIG here recently: http://code.haskell.org/hsffig/ Before running cabal install run make at the toplevel of the repo first. I have fixed some glitches recently, and adjusted both hsffig and ffipkg to work with contemporary GHC and Cabal (at least 1.6.0.x). I'd be glad to get any feedback on HSFFIG. E-mail me to golubovsky at gmail dot com. Thanks. -- Dimitry Golubovsky Anywhere on the Web ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building 'text-icu-0.1' on Windows
On Wed, May 13, 2009 at 4:46 PM, Alexander Dunlap alexander.dun...@gmail.com wrote: This isn't really helpful, but I received similar errors when trying to build icu-text on Windows If one of you has the time to dig into this and send a patch that corrects the problem, I'd welcome the help. As I'm sure you can tell, I developed text-icu on Unix, and I don't have regular enough Windows access to make debugging this a quick and easy matter. Thanks, B. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Structural sharing in haskell data structures?
jmaessen: On May 14, 2009, at 11:01 AM, Dan Doel wrote: On Thursday 14 May 2009 9:03:30 am Jan-Willem Maessen wrote: Hmm, I think neither of the data structures you name actually support both O(lg n) indexing and O(lg n) cons or append. That said, your point is well taken, so let's instead state it as a challenge: Data.Sequence has O(log n) index, concatenation, update, take, drop and splitAt, and O(1) cons, snoc, and viewing at both ends, according to the documentation. Yes. But large sequences end up being quite deep. Can a wide-fanout version be made that is actually faster? Note that the effective fanout of Hinze's finger trees is approximately e; consider effective fanouts of e^2 to e^4 (which may require substantially higher maximum fanout). Ah, so I see what Jan's asking for (I think). During the hackathon a number of us were experimenting with associated types to flatten groups of nodes in Data.Map (by unpacking them into the constructor). We were playing with fan out of up to 16 (while preserving pattern matching that makes it look like the original constructors). Good speedups followed, thanks to the improved data density. Here's a video (first part is about visualizing heap structures): http://vimeo.com/4258084 -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building 'text-icu-0.1' on Windows
On Thu, May 14, 2009 at 10:18 AM, Bryan O'Sullivan b...@serpentine.comwrote: If one of you has the time to dig into this and send a patch that corrects the problem, I'd welcome the help. As I'm sure you can tell, I developed text-icu on Unix, and I don't have regular enough Windows access to make debugging this a quick and easy matter. By the way, if you run into problems building or using text or text-icu, please file a ticket here: http://trac.haskell.org/text/newticket ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Pretty printing a tree
Hello. I would like to pretty print a tree in a way that its structure is easily perceived. For instance, consider the declarations: data Node a = Node a [Node a] type Tree a = [ Node a ] t = [ Node a [ Node b [] , Node c [ Node c1 [] , Node c2 [] ] , Node d [ Node d1 [ Node d1a [] ] , Node d2 [] ] ] ] Then the resulting of pretty printing the given tree would be something like the following: a | +-+ ||| bcd || +---++---+ | || | c1 c2 d1 d2 | d1a There is the module Text.PrettyPrint.HughesPJ, but it lacks examples on how to use the pretty print combinators, and it is not well docomented. I would like to see solutions for this problem, or clues on how to solve it. Regards, José Romildo ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Pretty printing a tree
Perhaps drawTree on http://www.haskell.org/ghc/docs/latest/html/libraries/containers/Data-Tree.html 2009/5/14 José Romildo Malaquias j.romi...@gmail.com Hello. I would like to pretty print a tree in a way that its structure is easily perceived. For instance, consider the declarations: data Node a = Node a [Node a] type Tree a = [ Node a ] t = [ Node a [ Node b [] , Node c [ Node c1 [] , Node c2 [] ] , Node d [ Node d1 [ Node d1a [] ] , Node d2 [] ] ] ] Then the resulting of pretty printing the given tree would be something like the following: a | +-+ ||| bcd || +---++---+ | || | c1 c2 d1 d2 | d1a There is the module Text.PrettyPrint.HughesPJ, but it lacks examples on how to use the pretty print combinators, and it is not well docomented. I would like to see solutions for this problem, or clues on how to solve it. Regards, José Romildo ___ 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] commending Design concepts in programming languages
On Tue, May 12, 2009 at 1:04 PM, Max Rabkin max.rab...@gmail.com wrote: On Tue, May 12, 2009 at 1:41 PM, Wolfgang Jeltsch g9ks1...@acme.softbase.org wrote: At least, I cannot remember seeing the other notation (first morphism on the left) in category theory literature so far. It’s just that my above-mentioned professor told me that category theorists would use the first-morphism-on-the-left notation. I've seen the notation f;g for g.f somewhere (and Wikipedia mentions it). I think it's less ambiguous than just fg (which I've seen for f.g too), but in Haskell we have the option of . A flipped application might be nice to go with it. How about $ ? FYI: Unicode U+2A3E Zed notation relational composition (small circle over a 9) Examples at http://staff.washington.edu/jon/z/toolkit.html#pair3 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] looking for suggestion on pattern matching problem
I am trying to analyze a list of items (say integers) for longest matches on patterns and their location on the list. One catch is that pattern may be defined in terms of other patterns. Example of patterns would be the any sequence of increasing numbers, or sequence of increasing numbers followed by upto 5 zeros then followed by any odd digits. I don't know much about the actual patterns, but would like to be able to define EDSL for composing the patterns and an execution environment to actually find the patterns. I like to find out various ways I can structure the problem and its trade offs. I appreciate any books, articles, suggestions, papers, etc on this type of problems. Thanks, Daryoush ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] hiddenness
Hello, When I am compiling a module, I get Could not find module 'Control.Module.State': it is a member of package mtl-1.1.0.2, which is hidden 1) What is the efficacy of hiddenness? 2) I have forgotten what tool I run to expose a package. ?? 3) In another vein, the code is using Data.Finitemap ... so I guess I must darcs install this? Regards, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] hiddenness
On Thu, May 14, 2009 at 10:51 PM, Vasili I. Galchin vigalc...@gmail.com wrote: Hello, When I am compiling a module, I get Could not find module 'Control.Module.State': it is a member of package mtl-1.1.0.2, which is hidden 1) What is the efficacy of hiddenness? As I understand it, the purpose is two-fold. Firstly, if you have multiple versions a package (or multiple packages containing the same module), you can hide the ones not in use. Second, it ensures you have declared all dependencies. 2) I have forgotten what tool I run to expose a package. ?? I've only ever had this when working with Cabal, where I have missed a dependency. In this case, it looks like you have an undeclared dependency on mtl. I'm not sure whether this arises in the non-Cabal case. 3) In another vein, the code is using Data.Finitemap ... so I guess I must darcs install this? I believe it was just uploaded to Hackage (it's obsolete, but useful for getting old code to run). HTH, Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] hiddenness
oh ... yes .. my .cabal file is incomplete! Thanks, Max. Vasili On Thu, May 14, 2009 at 3:56 PM, Max Rabkin max.rab...@gmail.com wrote: On Thu, May 14, 2009 at 10:51 PM, Vasili I. Galchin vigalc...@gmail.com wrote: Hello, When I am compiling a module, I get Could not find module 'Control.Module.State': it is a member of package mtl-1.1.0.2, which is hidden 1) What is the efficacy of hiddenness? As I understand it, the purpose is two-fold. Firstly, if you have multiple versions a package (or multiple packages containing the same module), you can hide the ones not in use. Second, it ensures you have declared all dependencies. 2) I have forgotten what tool I run to expose a package. ?? I've only ever had this when working with Cabal, where I have missed a dependency. In this case, it looks like you have an undeclared dependency on mtl. I'm not sure whether this arises in the non-Cabal case. 3) In another vein, the code is using Data.Finitemap ... so I guess I must darcs install this? I believe it was just uploaded to Hackage (it's obsolete, but useful for getting old code to run). HTH, Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] looking for suggestion on pattern matching problem
Sounds like you need regular expressions applied to the string representation, although the sequence of increasing numbers is not something any of the standard regexp packages do. So you will have to roll your own. Alternatively you could use one of the parsing libraries to parse the string and define sequence of increasing numbers using a stateful parser. Paul. Daryoush Mehrtash wrote: I am trying to analyze a list of items (say integers) for longest matches on patterns and their location on the list. One catch is that pattern may be defined in terms of other patterns. Example of patterns would be the any sequence of increasing numbers, or sequence of increasing numbers followed by upto 5 zeros then followed by any odd digits. I don't know much about the actual patterns, but would like to be able to define EDSL for composing the patterns and an execution environment to actually find the patterns. I like to find out various ways I can structure the problem and its trade offs. I appreciate any books, articles, suggestions, papers, etc on this type of problems. Thanks, Daryoush ___ 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] Pretty printing a tree
On Thu, May 14, 2009 at 03:58:18PM -0300, José Romildo Malaquias wrote: Then the resulting of pretty printing the given tree would be something like the following: a | +-+ ||| bcd || +---++---+ | || | c1 c2 d1 d2 | d1a There is the module Text.PrettyPrint.HughesPJ, but it lacks examples on how to use the pretty print combinators, and it is not well docomented. Text.PrettyPrint.HughesPJ is actually not a good tool for this, since it is for pretty-printing line-oriented material (i.e. source code). I actually have a library I was developing a while ago to do the sort of pretty-printing/layout of text that you're looking for, using a box model similar to that of TeX, but I never released it. Hopefully I'll get around to polishing and releasing it this summer. -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] looking for suggestion on pattern matching problem
Parsec 3 should be able to handle this pretty easily. It can parse any data structure that implements it's Stream class. Friendly, --Lane On Thu, 14 May 2009, Daryoush Mehrtash wrote: I am trying to analyze a list of items (say integers) for longest matches on patterns and their location on the list. One catch is that pattern may be defined in terms of other patterns. Example of patterns would be the any sequence of increasing numbers, or sequence of increasing numbers followed by upto 5 zeros then followed by any odd digits. I don't know much about the actual patterns, but would like to be able to define EDSL for composing the patterns and an execution environment to actually find the patterns. I like to find out various ways I can structure the problem and its trade offs. I appreciate any books, articles, suggestions, papers, etc on this type of problems. Thanks, Daryoush ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Data.Binary and little endian encoding
I actually need little endian encoding... wondering if anyone else hit this with Data.Binary. (because I'm working with Bell Lab's 9P protocol which does encode things on the network in little-endian order). Anyone got some tricks for this? Dave ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
leimy2k: I actually need little endian encoding... wondering if anyone else hit this with Data.Binary. (because I'm working with Bell Lab's 9P protocol which does encode things on the network in little-endian order). Anyone got some tricks for this? Yes! There are big, little and host-endian primitives in the Get/Put monads. http://hackage.haskell.org/packages/archive/binary/0.5.0.1/doc/html/Data-Binary-Put.html#v%3AputWord16le You can use these to build encoders directly. Cheers, Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
On Thu, May 14, 2009 at 8:40 PM, Don Stewart d...@galois.com wrote: leimy2k: I actually need little endian encoding... wondering if anyone else hit this with Data.Binary. (because I'm working with Bell Lab's 9P protocol which does encode things on the network in little-endian order). Anyone got some tricks for this? Yes! There are big, little and host-endian primitives in the Get/Put monads. http://hackage.haskell.org/packages/archive/binary/0.5.0.1/doc/html/Data-Binary-Put.html#v%3AputWord16le You can use these to build encoders directly. Cool... I just have to write my own encoder and decoder now. As a request could we get encodeLe decodeLe for a later version of this library? :-) That'd be totally awesome. Cheers, Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
leimy2k: On Thu, May 14, 2009 at 8:40 PM, Don Stewart d...@galois.com wrote: leimy2k: I actually need little endian encoding... wondering if anyone else hit this with Data.Binary. (because I'm working with Bell Lab's 9P protocol which does encode things on the network in little-endian order). Anyone got some tricks for this? Yes! There are big, little and host-endian primitives in the Get/Put monads. http://hackage.haskell.org/packages/archive/binary/0.5.0.1/doc/html/ Data-Binary-Put.html#v%3AputWord16le You can use these to build encoders directly. Cool... I just have to write my own encoder and decoder now. As a request could we get encodeLe decodeLe for a later version of this library? :-) That'd be totally awesome. Oh, you mean entirely different instances for all the current ones, that use LE encodings? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
On Thu, May 14, 2009 at 8:46 PM, Don Stewart d...@galois.com wrote: leimy2k: On Thu, May 14, 2009 at 8:40 PM, Don Stewart d...@galois.com wrote: leimy2k: I actually need little endian encoding... wondering if anyone else hit this with Data.Binary. (because I'm working with Bell Lab's 9P protocol which does encode things on the network in little-endian order). Anyone got some tricks for this? Yes! There are big, little and host-endian primitives in the Get/Put monads. http://hackage.haskell.org/packages/archive/binary/0.5.0.1/doc/html/ Data-Binary-Put.html#v%3AputWord16le You can use these to build encoders directly. Cool... I just have to write my own encoder and decoder now. As a request could we get encodeLe decodeLe for a later version of this library? :-) That'd be totally awesome. Oh, you mean entirely different instances for all the current ones, that use LE encodings? Well the library is leaning towards Network Byte Order in that it has encode/decode that only encode/decode for Big Endian. Us folks who have to do little endian all now have to write our own encoding/decoding :-) I'm speaking specifically of the encode/decode functions. I have no idea how they're implemented. Are you saying that encode is doing something really simple and the default encodings for things just happen to be big endian? If so, then I understand the pain but it still means I have to roll my own :-) I guess if one must choose, big endian kind of makes sense, except that the whole world is little endian now, except for networks :-) (No one *really* cares about anything but x86 anyway these days right?) I'm only half-kidding. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
I'm speaking specifically of the encode/decode functions. I have no idea how they're implemented. Are you saying that encode is doing something really simple and the default encodings for things just happen to be big endian? If so, then I understand the pain but it still means I have to roll my own :-) I guess if one must choose, big endian kind of makes sense, except that the whole world is little endian now, except for networks :-) (No one *really* cares about anything but x86 anyway these days right?) Oh, 'encode' has type: encode :: Binary a = a - ByteString it just encodes with the default instances, which are all network order: http://en.wikipedia.org/wiki/Endianness#Endianness_in_networking -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
On Thu, May 14, 2009 at 8:54 PM, Don Stewart d...@galois.com wrote: I'm speaking specifically of the encode/decode functions. I have no idea how they're implemented. Are you saying that encode is doing something really simple and the default encodings for things just happen to be big endian? If so, then I understand the pain but it still means I have to roll my own :-) I guess if one must choose, big endian kind of makes sense, except that the whole world is little endian now, except for networks :-) (No one *really* cares about anything but x86 anyway these days right?) Oh, 'encode' has type: encode :: Binary a = a - ByteString it just encodes with the default instances, which are all network order: http://en.wikipedia.org/wiki/Endianness#Endianness_in_networking Yeah I understand that Big Endian == Network Byte Order... which would be true, if I wasn't talking about Plan 9's 9P protocol which specifies little endian bytes on the wire (as far as I can tell anyway from the man page). Dave -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
On Thu, May 14, 2009 at 8:57 PM, David Leimbach leim...@gmail.com wrote: On Thu, May 14, 2009 at 8:54 PM, Don Stewart d...@galois.com wrote: I'm speaking specifically of the encode/decode functions. I have no idea how they're implemented. Are you saying that encode is doing something really simple and the default encodings for things just happen to be big endian? If so, then I understand the pain but it still means I have to roll my own :-) I guess if one must choose, big endian kind of makes sense, except that the whole world is little endian now, except for networks :-) (No one *really* cares about anything but x86 anyway these days right?) Oh, 'encode' has type: encode :: Binary a = a - ByteString it just encodes with the default instances, which are all network order: http://en.wikipedia.org/wiki/Endianness#Endianness_in_networking Yeah I understand that Big Endian == Network Byte Order... which would be true, if I wasn't talking about Plan 9's 9P protocol which specifies little endian bytes on the wire (as far as I can tell anyway from the man page). Dave FYI here's what I've ended up trying to write to negotiate the version of a 9p server: main = withSocketsDo $ do ainfo - getAddrInfo Nothing (Just 127.0.0.1) (Just 6872) -- hardcoded for now, it's an IRC filesystem server let a = head ainfo sock - socket AF_INET Stream defaultProtocol connect sock (addrAddress a) sendAll sock $ (toLazyByteString (putWord32le (fromIntegral (16 ::Int32 sendAll sock $ (encode (100 ::Int8)) sendAll sock $ (toLazyByteString (putWord32le (fromIntegral (1024 ::Int32 sendAll sock $ (encode (C.pack 9P2000)) I feel like I should use wireshark or something to watch the bytes :-) I'm not feeling very sure about this. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
On Thu, May 14, 2009 at 9:10 PM, David Leimbach leim...@gmail.com wrote: On Thu, May 14, 2009 at 8:57 PM, David Leimbach leim...@gmail.com wrote: On Thu, May 14, 2009 at 8:54 PM, Don Stewart d...@galois.com wrote: I'm speaking specifically of the encode/decode functions. I have no idea how they're implemented. Are you saying that encode is doing something really simple and the default encodings for things just happen to be big endian? If so, then I understand the pain but it still means I have to roll my own :-) I guess if one must choose, big endian kind of makes sense, except that the whole world is little endian now, except for networks :-) (No one *really* cares about anything but x86 anyway these days right?) Oh, 'encode' has type: encode :: Binary a = a - ByteString it just encodes with the default instances, which are all network order: http://en.wikipedia.org/wiki/Endianness#Endianness_in_networking Yeah I understand that Big Endian == Network Byte Order... which would be true, if I wasn't talking about Plan 9's 9P protocol which specifies little endian bytes on the wire (as far as I can tell anyway from the man page). Dave FYI here's what I've ended up trying to write to negotiate the version of a 9p server: main = withSocketsDo $ do ainfo - getAddrInfo Nothing (Just 127.0.0.1) (Just 6872) -- hardcoded for now, it's an IRC filesystem server let a = head ainfo sock - socket AF_INET Stream defaultProtocol connect sock (addrAddress a) sendAll sock $ (toLazyByteString (putWord32le (fromIntegral (16 ::Int32 sendAll sock $ (encode (100 ::Int8)) sendAll sock $ (toLazyByteString (putWord32le (fromIntegral (1024 ::Int32 sendAll sock $ (encode (C.pack 9P2000)) I totally forgot the tag part of 9p ugh. I think I should probably just go to bed now. I feel like I should use wireshark or something to watch the bytes :-) I'm not feeling very sure about this. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Data.Binary and little endian encoding
On a related matter, I am using Data.Binary to serialise data from haskell for use from other languages. The Data.Binary encoding of a Double is a long integer for the mantissa, and an int for the exponent. This doesn't work too well for interacting with other languages as I'd need to have an arbitrary precision int type there to decode/encode. The CORBA CDR standard encodes doubles in a big ended fashion like this (excuse my possibly incorrect ascii art): | byte | msb lsb | |--+---| |0 | S E6 E0 | |1 | E10 E9 E8 E7 F3 F2 F1 F0 | |2 | F11F4 | |3 | F19 F12 | |4 | F27 F20 | |5 | F35 F28 | |6 | F43 F36 | |7 | F51 F44 | Up until now, my code is pure haskell. Is it possible to get at the internal bits of a Double/CDouble in ghc? Or Should I use the FFI and write C to encode something like the above? Tim From: haskell-cafe-boun...@haskell.org [mailto:haskell-cafe-boun...@haskell.org] On Behalf Of David Leimbach Sent: Friday, 15 May 2009 1:58 PM To: Don Stewart Cc: Haskell Cafe Subject: Re: [Haskell-cafe] Data.Binary and little endian encoding On Thu, May 14, 2009 at 8:54 PM, Don Stewart d...@galois.com wrote: I'm speaking specifically of the encode/decode functions. I have no idea how they're implemented. Are you saying that encode is doing something really simple and the default encodings for things just happen to be big endian? If so, then I understand the pain but it still means I have to roll my own :-) I guess if one must choose, big endian kind of makes sense, except that the whole world is little endian now, except for networks :-) (No one *really* cares about anything but x86 anyway these days right?) Oh, 'encode' has type: encode :: Binary a = a - ByteString it just encodes with the default instances, which are all network order: http://en.wikipedia.org/wiki/Endianness#Endianness_in_networking Yeah I understand that Big Endian == Network Byte Order... which would be true, if I wasn't talking about Plan 9's 9P protocol which specifies little endian bytes on the wire (as far as I can tell anyway from the man page). Dave -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] I have forgotten .. my bad
Hello, darcs get --init ?? I want to pull down Data.FiniteMap. I have forgotten the path to Hackage .. I tried sudo darcs get http://hackage.haskell.org/ Data.FiniteMap [sudo] password for vigalchin: Invalid repository: http://hackage.haskell.org darcs failed: Failed to download URL http://hackage.haskell.org/_darcs/inventory : HTTP error (404?) ?? Obviously the code I am cabalizing needs to be upgraded(i.e. not using deprecated packages) but first I want it to build! Thanks, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary and little endian encoding
timd: On a related matter, I am using Data.Binary to serialise data from haskell for use from other languages. The Data.Binary encoding of a Double is a long integer for the mantissa, and an int for the exponent. This doesn't work too well for interacting with other languages as I'd need to have an arbitrary precision int type there to decode/encode. The CORBA CDR standard encodes doubles in a big ended fashion like this (excuse my possibly incorrect ascii art): | byte | msb lsb | |--+---| |0 | S E6 E0 | |1 | E10 E9 E8 E7 F3 F2 F1 F0 | |2 | F11F4 | |3 | F19 F12 | |4 | F27 F20 | |5 | F35 F28 | |6 | F43 F36 | |7 | F51 F44 | Up until now, my code is pure haskell. Is it possible to get at the internal bits of a Double/CDouble in ghc? Or Should I use the FFI and write C to encode something like the above? Yep, it's possible, just not portably so. Google for Data.Binary IEEE discussions. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
