Re: [Haskell-cafe] Typing efficient folds
Keith Battocchi wrote: data Nest a = Nil | Cons(a, (Nest (Pair a))) type Pair a = (a,a) pair f (a,b) = (f a, f b) efold :: forall n m b. (forall a. n a) - (forall a . (m a, n (Pair a)) - n a) - (forall a. Pair (m a) - m (Pair a)) - (forall l z. (l b - m (z b)) - Nest (l b) - n (z b)) efold e f g h Nil = e efold e f g h (Cons(x, xs)) = f(h x, efold e f g (g . pair h) xs) If the problem is just understanding the type error, it may help to manually check the types. You only need to look at the second branch of the function definition, since this is the case that generates the error. From the pattern-match, you get the type of xs: xs :: Nest (Pair (l b)) -- (1) Combining the type of f with the result type of the efold definition, you get the type of the result of the recursive call: efold e f g (g . pair h) xs :: n (Pair (z b)) -- (2) This function makes use of polymorphic recursion. To analyse the type of the recursive call, you need a fresh batch of type variables, so you can distinguish the types of the arguments to the recursive call from the types of the formal parameters of the function definition. Since the first three arguments to the recursive call are unchanged, you only need fresh variables for b, l and z. I'll use primed versions of these variables: efold e f g :: (l' b' - m (z' b')) - Nest (l' b') - n (z' b') -- (3) From (3), you get an alternative view of the type of xs: xs :: Nest (l' b') -- (4) You can now perform unification on these results. You need to be careful unifying with Pair types, since (Pair a) is really ((,) a a). Unifying (1) and (4), you get: Nest ((,) (l b) (l b)) ~ Nest (l' b') l' ~ (,) (l b) b' ~ (l b) -- (5) Unifying (2) and the result type from (3): n ((,) (z b) (z b)) ~ n (z' b') z' ~ (,) (z b) b' ~ (z b) -- (6) From (5) and (6), you require: l b ~ z b, and therefore l ~ z, but the forall l z in the type signature requires l and z to be independent. I'm no expert in nested data types, but I doubt there is any additional generality to be had from trying to distinguish l and z. In that case, you can write both l b and z b as a. You can also remove a superfluous tuple from the type definition: data Nest a = Nil | Cons a (Nest (Pair a)) type Pair a = (a,a) efold :: (forall a. n a) - (forall a. m a - n (Pair a) - n a) - (forall a. Pair (m a) - m (Pair a)) - (a - m a) - (Nest a - n a) efold e f g h Nil = e efold e f g h (Cons x xs) = f (h x) (efold e f g (g . pair h) xs) For example, to flatten a Nest to a simple list, you can take m to be Id and n to be [], something like this: nest = Cons 0 (Cons (1,2) (Cons ((3,4),(5,6)) Nil)) newtype Id a = Id a -- [0,1,2,3,4,5,6] flat_nest = efold [] (\(Id xs) ys - xs : concatMap (\(p,q) - [p,q]) ys) (\(Id x, Id y) - Id (x,y)) Id nest It's a little unpleasant having to use the Id type like this, but I can't see a way around it. I'd be interested to see an example with a non-trivial m. Regards, Matthew ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: old-time conflict when installing phooey
Hi, Daryoush Mehrtash dmehrt...@gmail.com writes: When I try to install phooey I get conflict with old-time that I am not sure how to resolve. Any ideas? cabal install phooey Resolving dependencies... cabal: dependencies conflict: ghc-6.10.1 requires old-time ==1.0.0.2 however old-time-1.0.0.2 was excluded because ghc-6.10.1 requires old-time ==1.0.0.1 1. Use command ghc-pkg list list package-list, then you will get two package-list, remove same package that exist *two* package-list. (Use command ghc-pkg unregister PackageName -force remove pacakge). 2. And then remove pacakge old-time-1.0.0.2, use command ghc-pkg unregister old-time-1.0.0.2 --force. Then everything is okay. -- Andy 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
[Haskell-cafe] RE: [Haskell] ANN control-monad-exception-0.1: Explicitly typed exceptions
Is there a Haskell Wiki page on extensible exceptions? The paper is a fine reference, it'd be cool to have a wiki page giving programmer-oriented guidance, saying what comes with GHC what other packages are available and some simple examples of how to use them. Simon | -Original Message- | From: haskell-boun...@haskell.org [mailto:haskell-boun...@haskell.org] On Behalf Of | Pepe Iborra | Sent: 25 April 2009 19:52 | To: hask...@haskell.org | Subject: [Haskell] ANN control-monad-exception-0.1: Explicitly typed exceptions | | The control-monad-exception package [1] provides explicitly typed | exceptions for Haskell. | In other words, this is a perfect example of bundling in a Haskell | library what for other | programming languages is a native feature. | | The type of a computation in the EM monad carries a list of the exceptions that | the computation may throw. A exception is raised with 'throw', which | in addition adds it | to the type, and captured with 'catch', which correspondingly removes | it from the type. | Only safe computations (all exceptions handled) can escape from the monad. | | The encoding used for the exception list is based on a phantom type | variable carrying a | @Throws@ constraint for every exception type. Catching an exception | @e@ satifies the constraint | @Throws e@ thus removing it from the type. It is possible to teach | Throws about exception subtyping | by manually inserting new instances declaring the subtyping relations | between exceptions. I don't | believe there is a better way to handle this, as the existential | wrapper encoding used | for Control.Exception.SomeException does not reveal the subtyping | relations, but ideas are | welcome. | | Example | | GHCi infers the following types | | eval :: (Throws DivideByZero l, Throws SumOverflow l) = Expr - EM l Double | eval `catch` \ (e::DivideByZero) - return (-1) :: Throws | SumOverflow l = Expr - EM l Double | runEM (eval `catch` \ (e::SomeException) - return (-1)) :: Expr - Double | | for the code below. | | | import Control.Monad.Exception | import Data.Typeable | | data Expr = Add Expr Expr | Div Expr Expr | Val Double | eval (Val x) = return x | eval (Add a1 a2) = do | v1 - eval a1 | v2 - eval a2 | let sum = v1 + v2 | if sum v1 || sum v2 then throw SumOverflow else return sum | eval (Div a1 a2) = do | v1 - eval a1 | v2 - eval a2 | if v2 == 0 then throw DivideByZero else return (v1 / v2) | | data DivideByZero = DivideByZero deriving (Show, Typeable) | data SumOverflow = SumOverflow deriving (Show, Typeable) | | instance Exception DivideByZero | instance Exception SumOverflow | | | Comments and patches are welcome. | Cheers, | Pepe Iborra | | [1] - http://hackage.haskell.org/cgi-bin/hackage-scripts/package/control-monad- | exception | ___ | Haskell mailing list | hask...@haskell.org | http://www.haskell.org/mailman/listinfo/haskell ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Memory usage of cabal install
Hello Haskell-Café, I have a problem with high memory usage of cabal-install. Whenever I try to install or upgrade a package, cabal manages to consume 1,3G of memory before I killed it (on a 32-bit machine with 1 GB of memory). Increasing verbosity does not help, memory consumption goes up after the message Resolving dependencies... shows up. I use ghc 6.8.2 and cabal-install version 0.5.1 using version 1.4.0.1 of the Cabal library. Is there a workaround? I would like to avoid fetching building packages manually. -- Krzysztof Kościuszkiewicz Simplicity is the ultimate sophistication -- Leonardo da Vinci ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Memory usage of cabal install
Jakiej platformy dokładnie dotyczy Twój problem? Proponuję upgrade do najnowszej wersji - można ją ściągnąć ze strony GHC. Pozdrawiam Krzysztof Skrzętnicki 2009/4/27 Krzysztof Kościuszkiewicz k.kosciuszkiew...@gmail.com: Hello Haskell-Café, I have a problem with high memory usage of cabal-install. Whenever I try to install or upgrade a package, cabal manages to consume 1,3G of memory before I killed it (on a 32-bit machine with 1 GB of memory). Increasing verbosity does not help, memory consumption goes up after the message Resolving dependencies... shows up. I use ghc 6.8.2 and cabal-install version 0.5.1 using version 1.4.0.1 of the Cabal library. Is there a workaround? I would like to avoid fetching building packages manually. -- Krzysztof Kościuszkiewicz Simplicity is the ultimate sophistication -- Leonardo da Vinci ___ 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] Memory usage of cabal install
On Mon, 2009-04-27 at 12:56 +0200, Krzysztof Kościuszkiewicz wrote: Hello Haskell-Café, I have a problem with high memory usage of cabal-install. Whenever I try to install or upgrade a package, cabal manages to consume 1,3G of memory before I killed it (on a 32-bit machine with 1 GB of memory). Increasing verbosity does not help, memory consumption goes up after the message Resolving dependencies... shows up. I use ghc 6.8.2 and cabal-install version 0.5.1 using version 1.4.0.1 of the Cabal library. The only instance of this behaviour that I know of involves using that version of cabal-install with ghc-6.10.1. http://haskell.org/cabal/FAQ.html#cabal-goes-into-an-infinite-loop--runs-out-of-memory The older version of cabal-install goes into an infinite loop when using ghc-6.10, when it is presented with two installed versions of the base package (and one depends on the other). In version 0.6.x cabal-install was updated to understand this situation. Are you absolutely sure you are using ghc 6.8 and not 6.10? Is there a workaround? I would like to avoid fetching building packages manually. If you're using ghc 6.10 then the solution is to update to cabal-install 0.6.x. If you're quite sure you are using 6.8 then the bug is unknown. It may still be worth trying upgrading to cabal-install 0.6.x. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] old-time conflict when installing phooey
On Sun, 2009-04-26 at 21:49 -0700, Daryoush Mehrtash wrote: When I try to install phooey I get conflict with old-time that I am not sure how to resolve. Any ideas? cabal install phooey Resolving dependencies... cabal: dependencies conflict: ghc-6.10.1 requires old-time ==1.0.0.2 however old-time-1.0.0.2 was excluded because ghc-6.10.1 requires old-time ==1.0.0.1 This looks very similar to: http://haskell.org/cabal/FAQ.html#dependencies-conflict but with a different core package. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Is 78 characters still a good option? Was: breaking too long lines
Richard O'Keefe wrote: On 25 Apr 2009, at 8:59 pm, Miguel Mitrofanov wrote: Something like newtype MyCoolMonad = MyCoolMonad (FirstTransformer (SecondTransformer (ThirdTransformer Whatever))) deriving (Functor, Monad, FirstClass, SecondClass, ThirdClass, SomeOtherClass) [...] For what it's worth, my personal Haskell style lines up data T = C1 ... | ... | Cn ... deriving (...) This has the clear advantage that indentation does not depend on the length of the type name as in the quite typical layout of Xiao-Yong Jin: http://www.haskell.org/pipermail/haskell-cafe/2009-April/060541.html so I'd have this as newtype MyCoolMonad = MyCoolMonad (FirstTransformer (SecondTransformer (ThirdTransformer Whatever))) deriving (Functor, Monad, FirstClass, SecondClass, ThirdClass, SomeOtherClass) where the longest line is 86 columns. (which is still too long as my reply-wrap proofs.) [...] However, indenting by 3 or 6 characters depending on data or newtype is also a bit arbitrary. Consider: newtype MyCoolMonad = MyCoolMonad (FirstTransformer (SecondTransformer (ThirdTransformer Whatever))) deriving ( Functor, Monad, FirstClass, SecondClass, ThirdClass , SomeOtherClass) Either all alternatives fit on one line or they go on separate lines each. The same should apply to all components of one alternative. Additionally, as above, a long type-application may need to be broken over several lines. (Breaking before = and having = above | looks also nice.) Pretty-printing a comma-separated list (following deriving) is an extra subject with a couple of variations: Putting commas in the front, better indicates the continuation, but the extra space following the open bracket ( looks a bit odd. (Surely one could also leave a space before the closing bracket, although I wouldn't like spaces around all brackets.) The alternative: (Functor, Monad, FirstClass, SecondClass, ThirdClass, SomeOtherClass) has the disadvantage, that the second line is only indented by one character (relative to the previous one), but intending further (+1 or +3 or even one less) is an alternative. (I'm no friend of putting the closing bracket on a separate line in the same column as the opening one. Too easily such indentations are messed up.) Cheers Christian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Memory usage of cabal install
On Mon, Apr 27, 2009 at 02:10:28PM +0100, Duncan Coutts wrote: [...] Increasing verbosity does not help, memory consumption goes up after the message Resolving dependencies... shows up. I use ghc 6.8.2 and cabal-install version 0.5.1 using version 1.4.0.1 of the Cabal library. The only instance of this behaviour that I know of involves using that version of cabal-install with ghc-6.10.1. http://haskell.org/cabal/FAQ.html#cabal-goes-into-an-infinite-loop--runs-out-of-memory [...] Are you absolutely sure you are using ghc 6.8 and not 6.10? Yes: k...@copper:~$ ghc -V ; cabal -V The Glorious Glasgow Haskell Compilation System, version 6.8.2 cabal-install version 0.5.1 using version 1.4.0.1 of the Cabal library Is there a workaround? I would like to avoid fetching building packages manually. If you're using ghc 6.10 then the solution is to update to cabal-install 0.6.x. If you're quite sure you are using 6.8 then the bug is unknown. It may still be worth trying upgrading to cabal-install 0.6.x. I'll try that and report success/failure. Thanks, -- Krzysztof Kościuszkiewicz Simplicity is the ultimate sophistication -- Leonardo da Vinci ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] subscribing to the comments, online Real World Haskell
Michael P Mossey wrote: Michael P Mossey wrote: However, I would like some ability to subscribe to specific comments. I want to see if people have replied to me or what the latest discussion is. Okay, to follow up my own post, I discovered the subscription button for each chapter. That's good. However, using Live Bookmarks in Firefox, I have a problem... the links that should bring me to the book itself (with the comment in context) are broken. Maybe this is the fault of Live Bookmarks. Anyone recommend another program for subscribing to comments? I recommend bloglines.com -- pretty nice interface and works well. -- John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] how can one load Prelude into ghci?
One reason it would be nice to be able to do this, is you could then
get lambdabot :src style listings of prelude function definitions by
using the ghci debugger and :list for prelude functions.
is this possible? so far I have tried
thart...@ubuntu:~/haskellInstalls/ghcInstalls/source/ghc-6.10.1/libraries/basehead
Prelude.hs
{-# OPTIONS_GHC -XNoImplicitPrelude #-}
-
thart...@ubuntu:~/haskellInstalls/ghcInstalls/source/ghc-6.10.1/libraries/baseghci
-i. Prelude.hs
GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
command line: module `Prelude' is not loaded
thart...@ubuntu:~/haskellInstalls/ghcInstalls/source/ghc-6.10.1/libraries/baseghci
Prelude.hs
GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
command line: module `Prelude' is not loaded
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Re: [Haskell-cafe] ANN: atom-0.0.2
tomahawkins: Atom is a DSL in Haskell for designed hard realtime embedded programs. At Eaton, we are using it to control hydraulic hybrid refuse trucks and shuttle buses. After my talk at CUFP (http://cufp.galois.com/2008/schedule.html), a few people inquired about atom -- I finally had a chance to upload it to Hackage. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/atom-0.0.2 Some new enhancements: - A simple rule scheduler for load balancing. - Signal probing for debug and data logging. - Functional coverage to monitor which rules have executed. - Started integration with the Yices SMT solver for bounded model checking. Experiences with our Eaton project: - 5K lines of Haskell/atom replaced 120K lines of matlab, simulink, and visual basic. - 2 months to port simulink design to atom. - 3K lines of atom generates 22K lines of embedded C. - Design composed of 450 atomic state transition rules. - Rules with execution periods from 1ms to 10s all scheduled at compile time to a 1 ms main loop. - 3 minute compilation time from atom source to ECU. - Atom design clears electronic/sw testing on first pass. - Currently in vehicle testing with no major issues. Congratulations on the release! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Memory usage of cabal install
On Mon, Apr 27, 2009 at 02:10:28PM +0100, Duncan Coutts wrote: If you're using ghc 6.10 then the solution is to update to cabal-install 0.6.x. If you're quite sure you are using 6.8 then the bug is unknown. It may still be worth trying upgrading to cabal-install 0.6.x. I've upgraded to cabal-install 0.6.2 and the problem went away. Thanks for help! -- Krzysztof Kościuszkiewicz Simplicity is the ultimate sophistication -- Leonardo da Vinci ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to install HOpenGL to Windows?
Am Montag, 27. April 2009 00:11:20 schrieb Duncan Coutts: On Sun, 2009-04-26 at 19:03 +0200, Sven Panne wrote: [...] * How to link programs using OpenGL This is because the GL libs are called different names on different platforms right? But they're consistent within each platform, it's just Windows vs everyone else isn't it? How about: if os(windows) extra-libraries: gl32 else extra-libraries: GL As usual, things are always a bit trickier than they appear initially: On non- Windows systems it is not always sufficient to link against libGL alone, sometimes you'll have to link against several X11 libs, too. I am not sure if this is still a widespread problem, but in the past it was. Hopefully most *nices get their dynamic library dependencies right nowadays... :-P Windows is, as always, a special beast, especially when you take Cygwin into account: On Cygwin you can either build against the native OpenGL or against Cygwin's X11 OpenGL. This can be configure via --without-x. How can we do this in .cabal files? And MacOS had some peculiarities which I can't fully remember anymore, too. * The Haskell types corresponding to the OpenGL types Does hsc2hs #type not help us with this? [...] I am not sure, because I haven't had a look at hsc2hs for a long time, and at the beginning of the OpenGL binding there were no such tools, not even the FFI in its current form. Perhaps I'll have a look at this, but to make this work, I am sure that we'll have to solve the next item: * To do the former: How to find the OpenGL C headers What's needed here? Are they not in standard locations? Cabal has support for users to specify non-standard locations. What is a standard location for headers on Windows? There is no such concept. On *nices you look into /usr/include and /usr/local/include, and that's it, unless the user tells you something different. And Apple is always a very creative company, so they decided to put *their* OpenGL headers in a completely different path where no -I flag can help... Having access to the OpenGL headers is crucial for finding out which C types are behind OpenGL types like GLint, GLenum, ... The OpenGL spec only specifies minimum requirements for these types and *not* their C mapping. * The library calling convention This is stdcall on Windows and ccall everywhere else right? How about: if os(windows) cpp-options: -DCALLCONV=stdcall else cpp-options: -DCALLCONV=ccall This should be fine, at least when we solve the Cygwin problem discussed above: The X11 OpenGL libraries on Windows do *not* use stdcall, only the native OpenGL libraries. (The whole calling convention story on Windows really, really sucks, IMHO...) Using CPP for this simple task doesn't look right, but with the current FFI I don't see a way around this, which is a shame. Any ideas/proposals for a FFI change? * How to load OpenGL extensions I don't know enough of the details here to comment. You'll have to know if wglGetProcAddress, NSAddressOfSymbol (+ a bit more code) or some variant of glXGetProcAddress has to be used, plus their necessary headers. This is probably doable via some platform switches in Cabal, too. A few general remarks: * Ignoring the (usual) Windows trouble, I like autoconf's approach of testing features instead of relying on extremely fragile platform conditionals. The latter are a constant source of troubles and from a SW engineering point of view, they are a clear step backwards. The I know my platform approach which you basically propose reminds me of the xmkmf hell from the last millennium: If X11 didn't know your platform, you had a *lot* of fun getting the platform description right. * We can go this autoconf-free route, but this is a part of my bindings which I definitely won't maintain in full time. I'll be happy to review and accept patches, but making things work on Windows, Cygwin, Linux, *BSD, MacOS X, ... is a lot of work, which is a fact I have painfully learned in the past few years. The autoconf code may be ugly, but the tons of platform differences are ugly, to. I want to work on the binding itself mainly, not on the build system, which currently works. To repeat myself: Patches are happily accepted, but I propose incremental changes and heavy testing on various platforms. * Most of the tasks my autoconf scripts perform are not specific to OpenGL at all. I guess that most bindings for non-trivial C libraries face the same challenges (Where are my libs? Where are my headers? What are my types?) Having good Cabal support for these would be very nice. Cheers, S. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Thread priority?
lane: Is there any interest or movement in developing thread priority or any other realtime support in Haskell? I think thread priorities would be really cool :) -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Thread priority?
semanticphilosopher: Count me in too I've got a library that endeavours to deliver 'rate-equivalence' - i.e there may be some jitter in when the events should have occurred but their long term rate of progress is stable. Testing has shown that I can get events to occur at the right time within 1ms (99%+ of the time, with 50%+ of the events 0.5ms) - choose your O/S carefully though. And this is without resorting to marking the threads as real time with the kernel. If it matters you can tune the scheduling to further reduce the timer scheduling latency (at the cost of more CPU) and increase the fidelity of event timing another order of magnitude or more. As for 'garbage collection ruins my real time properties' argument - I've been pragmatic about this, you can configure the scheduler to go and perform a GC if it knows that it is going to sleep for a while (yes, this doesn't resolve the issues of external events arriving in that time but read on) but not perform that too often. Turning off GHCs timers (to stop it garbage collecting after it has actually been idle for a while) and having code that doesn't create vast amounts of garbage means that a GC takes 0.1ms. Now if I could see within Haskell the amount of heap that has been recently mutated and some other GC statistics when it was running I could even decide to schedule that more effectively. You could actually do this by importing symbols from Stats.c in the runtime (the same variables used for +RTS -sstderr output). I'm not sure anyone's ctually tried this yet though, but the effect would be a program that can monitor its own heap health. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Thread priority?
semanticphilosopher: Count me in too I've got a library that endeavours to deliver 'rate-equivalence' - i.e there may be some jitter in when the events should have occurred but their long term rate of progress is stable. Testing has shown that I can get events to occur at the right time within 1ms (99%+ of the time, with 50%+ of the events 0.5ms) - choose your O/S carefully though. And this is without resorting to marking the threads as real time with the kernel. If it matters you can tune the scheduling to further reduce the timer scheduling latency (at the cost of more CPU) and increase the fidelity of event timing another order of magnitude or more. As for 'garbage collection ruins my real time properties' argument - I've been pragmatic about this, you can configure the scheduler to go and perform a GC if it knows that it is going to sleep for a while (yes, this doesn't resolve the issues of external events arriving in that time but read on) but not perform that too often. Turning off GHCs timers (to stop it garbage collecting after it has actually been idle for a while) and having code that doesn't create vast amounts of garbage means that a GC takes 0.1ms. Now if I could see within Haskell the amount of heap that has been recently mutated and some other GC statistics when it was running I could even decide to schedule that more effectively. We use this to create synthetic network traffic sources and other timing/performance related activities in the wide area context - it serves our needs. This is very interesting. Do you have any further documentation / notes on controlling jitteriness? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Typing efficient folds
Matthew Brecknell haskell at brecknell.org writes: [...] Nest ((,) (l b) (l b)) ~ Nest (l' b') l' ~ (,) (l b) b' ~ (l b) -- (5) Unifying (2) and the result type from (3): n ((,) (z b) (z b)) ~ n (z' b') z' ~ (,) (z b) b' ~ (z b) -- (6) From (5) and (6), you require: l b ~ z b, and therefore l ~ z, but the forall l z in the type signature requires l and z to be independent. Thanks for explicitly writing out the unification steps; this makes it perfectly clear where things are going wrong. I was hoping to be able to have b' ~ b, l' b' ~ (l b, l b), and z' b' ~ (z b, z b). I guess it makes sense that these types can't be inferred - is there any way to explicitly add signatures somewhere so that these alternate interpretations will be used instead? This would allow l and z to remain independent. [...] efold :: (forall a. n a) - (forall a. m a - n (Pair a) - n a) - (forall a. Pair (m a) - m (Pair a)) - (a - m a) - (Nest a - n a) efold e f g h Nil = e efold e f g h (Cons x xs) = f (h x) (efold e f g (g . pair h) xs) For example, to flatten a Nest to a simple list, you can take m to be Id and n to be [], something like this: nest = Cons 0 (Cons (1,2) (Cons ((3,4),(5,6)) Nil)) newtype Id a = Id a -- [0,1,2,3,4,5,6] flat_nest = efold [] (\(Id xs) ys - xs : concatMap (\(p,q) - [p,q]) ys) (\(Id x, Id y) - Id (x,y)) Id nest It's a little unpleasant having to use the Id type like this, but I can't see a way around it. I'd be interested to see an example with a non-trivial m. It may depend on your notion of trivial, but if you've got a Nest [a] and want to get the sum of the lengths of the lists, you'd want m a to be something like K Int a where K t a = K t Thanks again for your help. Regards, Keith ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Converting IO [XmlTree] to [XmlTree]
Achim Schneider wrote: In other words: 1) Explain Pointed 2) Explain Functor 3) Explain Applicative 4) Explain Monad Why Pointed first? Functor seems more useful and more basic. Tillmann ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Converting IO [XmlTree] to [XmlTree]
Tillmann Rendel wrote: Achim Schneider wrote: In other words: 1) Explain Pointed 2) Explain Functor 3) Explain Applicative 4) Explain Monad Why Pointed first? Functor seems more useful and more basic. They are in order of power: every monad is an applicative; every applicative is a functor; every functor is pointed. Though I can't think of any non-functor pointiness at the moment. Martijn. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci debugger problem with :continue. is it broken, or is it me?
Most enlightening, thanks. The same effect can be seen with Debug.Trace.trace around the two versions of f. I suppose this means that the points-free/pattern binding-style version is a bit less work for ghc to execute (fewer reductions), whereas the version with lambda bound variables is easier to debug. On balance, I think I'll frequently write my functions with lambda bound variables then. Getting better use out of the ghc debugger seems worth the few extra cycles. 2009/4/26 Bernie Pope florbit...@gmail.com: 2009/4/25 Thomas Hartman tphya...@gmail.com In the program below, can someone explain the following debugger output to me? After :continue, shouldn't I hit the f breakpoint two more times? Why do I only hit the f breakpoint once? Is this a problem in the debugger? thart...@ubuntu:~/haskell-learning/debuggercat debugger.hs -- try this: -- ghci debugger.hs -- :break f -- :trace t -- :history -- should show you that f was called from h t = h . g . f $ hey! t2 = h . g . f $ heh! t3 = h . g . f $ wey! f = (f -- ++) g = (g -- ++) h = (h -- ++) ts = do putStrLn $ t putStrLn $ t2 putStrLn $ t3 What you are observing is really an artifact of the way breakpoints are attached to definitions in the debugger, and the way that GHCi evaluates code. f is clearly a function, but its definition style is a so-called pattern binding. The body contains no free (lambda bound) variables, so it is also a constant. GHCi arranges for f to be evaluated at most once. The breakpoint associated with the definition of f is fired if and when that evaluation takes place. Thus, in your case it fires exactly once. You can re-write f to use a so-called function binding instead, by eta-expansion (introduce a new fresh variable, and apply the function to it on both sides): f x = (f -- ++) x This denotes the same function, but the breakpoint on f works differently. In this case, a breakpoint attached to f will fire whenever an application of f is reduced. If you write it this way you will see that the program stops three times instead of one. You might ask: if both definitions denote the same function, why does the debugger behave differently? The short answer is that the debugger in GHCi is an operational debugger, so it exposes some of the operational details which may be invisible in a denotational semantics. In this case it revels that GHCi treats the two definitions of f differently. Cheers, Bernie. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] how can one load Prelude into ghci?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On Apr 27, 2009, at 12:25 , Thomas Hartman wrote: One reason it would be nice to be able to do this, is you could then get lambdabot :src style listings of prelude function definitions by using the ghci debugger and :list for prelude functions. I think up-to-date binary versions are preferred over source versions (thus the debugger is limited in what it can do with the Prelude). You would have to copy all the Prelude sources and modify them to make them look newer. You don't need other hackery beyond that, but that's plenty enough; GHC's Prelude isn't a single file or even a small collection of files. (It might be possible to borrow the Online Report's Prelude... won't be optimum but if you're going to interpret it won't be anyway) - -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.10 (Darwin) iEYEARECAAYFAkn2GccACgkQIn7hlCsL25UOhQCgtaAgs5/bLmIJ0hM+Her7HmN3 aakAnRXKJpelTrPMfuGLf2Ro8obZET+K =UB0V -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Can subclass override its super-class' default implementation of a function?
I'm not sure if this is possible at all. I'd like to do something like this: class A a where foo :: a - Double foo a = 5.0 class (A a) = B a where foo a = 7.0 data Blah = Blah data Bar = Bar instance A Blah instance B Bar let blah = Blah bar = Bar foo blah -- should print out 5 foo bar -- should print out 7 Basically, I have a bunch of instances that have a common functionality but I'd like to be able to group those instances and give each group a different default implementation of that functionality. It's so easy to do this in Java, for example, but I have no idea how to do it in Haskell. The above example will not compile, btw. Thanks a lot -- View this message in context: http://www.nabble.com/Can-subclass-override-its-super-class%27-default-implementation-of-a-function--tp23264975p23264975.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Converting IO [XmlTree] to [XmlTree]
2009/04/21 Manlio Perillo manlio_peri...@libero.it: Luke Palmer ha scritto: And many other permutations, with differing degrees of laziness and parametericity. As long as you stricly read a string from the socket, this is ok. But you can not read a string lazily. Why not? It changes the way in which the program fails (if it does) but it does not change the result. -- Jason Dusek ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Can subclass override its super-class' default implementation of a function?
siki wrote: I'm not sure if this is possible at all. I'd like to do something like this: class A a where foo :: a - Double foo a = 5.0 class (A a) = B a where foo a = 7.0 This is currently not possible in Haskell. It's been proposed, though: http://haskell.org/haskellwiki/Class_system_extension_proposal If you have an actual example we might be able to come up with a different way of modelling it so that it does what you want, though. Martijn. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Can subclass override its super-class' default implementation of a function?
No, but functionality similar to this has been proposed several times, under the name Class Aliases [1]. The big problem is in the definition of B: class (A a) = B a where ... In this case, you must make something an instance of A before it can be an instance of B, and, in order to make something an instance of A, you must provide an implementation of foo. Not providing an implementation is the same as providing the default. With the class alias proposal you would write class B a = A a where foo a = 7.0 In this case, (B a) and (A a) are the same class, but provide different default implementations for the methods. So you *cannot* declare something an instance of both B and A. But if you declare something an instance of B without providing an implementation of foo, it would use B's default, whereas instances of A would use A's default. Unfortunately, I don't believe anyone is working on implementing this proposal. It's high on my list of desired features, but I think that not all the details have been figured out with how it interacts with other features of the language. -- ryan [1] http://repetae.net/recent/out/classalias.html, http://haskell.org/haskellwiki/Class_alias On Mon, Apr 27, 2009 at 2:00 PM, siki ga...@karamaan.com wrote: I'm not sure if this is possible at all. I'd like to do something like this: class A a where foo :: a - Double foo a = 5.0 class (A a) = B a where foo a = 7.0 data Blah = Blah data Bar = Bar instance A Blah instance B Bar let blah = Blah bar = Bar foo blah -- should print out 5 foo bar -- should print out 7 Basically, I have a bunch of instances that have a common functionality but I'd like to be able to group those instances and give each group a different default implementation of that functionality. It's so easy to do this in Java, for example, but I have no idea how to do it in Haskell. The above example will not compile, btw. Thanks a lot -- View this message in context: http://www.nabble.com/Can-subclass-override-its-super-class%27-default-implementation-of-a-function--tp23264975p23264975.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ 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] Can subclass override its super-class' default implementation of a function?
The actual problem is quite similar to the one that I provided or to the one in the description of the proposed extension that you linked. Someone on another forum suggested record functions but I'm not sure I understood correctly how that would work around this problem. Any suggestion is greatly appreciated! Thanks, -Gabor Martijn van Steenbergen-2 wrote: siki wrote: I'm not sure if this is possible at all. I'd like to do something like this: class A a where foo :: a - Double foo a = 5.0 class (A a) = B a where foo a = 7.0 This is currently not possible in Haskell. It's been proposed, though: http://haskell.org/haskellwiki/Class_system_extension_proposal If you have an actual example we might be able to come up with a different way of modelling it so that it does what you want, though. Martijn. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- View this message in context: http://www.nabble.com/Can-subclass-override-its-super-class%27-default-implementation-of-a-function--tp23264975p23265759.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Question about implementing an off-side rule in Parsec 2
Hello everyone, I'm doing a bachelor project focused on comparing parsers. One of the parser libraries I'm using is Parsec (2) and I'm going to implement a very small subset of haskell with it, with as most important feature the off-side rule (indentation based parsing) used in function definitions and possibly in where clauses. But I'm still a bit stuck on how to implement this cleanly. I tried to search for some examples on blogs but I haven't found anything yet. As far as I can see the way to go would be using getState and updateState methods defined in Parsec.Prim and to use the methods in Parsec.Pos to compare the difference in indendation for tokens. But I haven't completely wrapped my head around any state monad yet and I don't understand Parsec enough yet to see how to use the methods Parsec.Pos and state easily. Some examples or pointers to something to read would really be helpful. Thanks in advance, Bas van Gijzel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Question about implementing an off-side rule in Parsec 2
On Mon, Apr 27, 2009 at 2:41 PM, Bas van Gijzel neneko...@gmail.com wrote: Hello everyone, I'm doing a bachelor project focused on comparing parsers. One of the parser libraries I'm using is Parsec (2) and I'm going to implement a very small subset of haskell with it, with as most important feature the off-side rule (indentation based parsing) used in function definitions and possibly in where clauses. But I'm still a bit stuck on how to implement this cleanly. I tried to search for some examples on blogs but I haven't found anything yet. As far as I can see the way to go would be using getState and updateState methods defined in Parsec.Prim and to use the methods in Parsec.Pos to compare the difference in indendation for tokens. I've never tried to implement a whitespace sensitive parser like you'd need for Haskell or Python, but my thought was that maybe you use a stack and you push/pop from it when the indentation level changes. That way, I think you could isolate the part of the parser that handles changes in indentation from the rest. Maybe I haven't thought about this enough yet because I'm not sure what I would store on the stack. In some sense, you want the indentation level change to determine which production(s) of the grammar you are looking for. You might also use it to track scope so that you know the scope of the names in the program source. But I haven't completely wrapped my head around any state monad yet and I don't understand Parsec enough yet to see how to use the methods Parsec.Pos and state easily. Some examples or pointers to something to read would really be helpful. I'd start by playing with some toy examples in the State monad, then try implementing a State monad. Only look at the real implementation when you get stuck. Once you get State, then go back to Parsec which is more complex. This way you'll be in over your head less. Good luck, Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] LAST CALL: Haskell Communities and Activities Report
Dear Haskellers, It is not yet too late to contribute to the May 2009 edition of the Haskell Communities and Activities Report. If you haven't already, please write an entry for your new project, or update your old entry. Please mail your entries to h...@haskell.org in LaTeX format. More information can be found in the original Call for Contributions at http://www.haskell.org/pipermail/haskell/2009-April/021180.html I look forward to receiving your contributions. Thanks a lot, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:vo...@tcs.inf.tu-dresden.de ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Can subclass override its super-class' defaultimplementation of a function?
Basically, I have a bunch of instances that have a common functionality but I'd like to be able to group those instances and give each group a different default implementation of that functionality. It's so easy to do this in Java, for example, but I have no idea how to do it in Haskell. The above example will not compile, btw. Before going into language extensions, is there anything wrong with: class C a where foo :: a - Double fooA a = 5.0 --default A fooB a = 7.0 -- default B data Blah = Blah data Bar = Bar instance C Blah where foo = fooA instance C Bar where foo = fooB blah = Blah bar = Bar main = do print $ foo blah -- should print out 5 print $ foo bar -- should print out 7 It seems to match your spec. Claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Announce: GraphViz: Change of Maintainer
I no longer have the time to continue development of the (apparently, judging from the number of emails I'm getting, rather popular) graphviz package. Fortunately, Ivan Lazar Miljenovic who has extended it himself and sent me patches (some of which I did get round to folding in) has agreed to take on the package. Please direct all further queries to him! Many thanks Ivan! Matthew ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] createProcess problem
Hello, I am trying to use createProcess. Following is a small fragment. I am trying to run a program called blastall (a bio-informatics program). It is kind of like mv/cp/ln on Unix platforms (where the executable examines the program, i.e. arg[0], and then provides appropriate behavior/semantics). In the case of blastall, it alters its behavior based on the -p(program) CLI argument.WSo in the following it should provide nucleotide behavior ... that is what the 'n' on the end of blastn means. import System.Process main = do handle - runProcess blastall -- executable [-p blastn] -- CLI args Nothing-- optional cwd Nothing-- optional env Nothing-- optional stdin Nothing-- optional stdout Nothing-- optional stderr return () When I run this program with ghci, blastall is not a happy camper. It is complaining about -p blastn: [NULL_Caption] ERROR: Program name undefined: blastn the space between the double quote and 'b' is really there!!! [NULL_Caption] ERROR: Program name undefined: blastn Yet if I run 'blastall -p blastn' from the DOS prompt no errors(I will try tonight on my Linux machine). If I try 'blastall -p bozo from the DOS prompt I get the same two errors as when I run my test program using ghci. I feel that it has something to do with double quotes in Haskell ... probably something obviously silly that I am doing. Any ideas? Kind regards, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Can subclass override its super-class' default implementation of a function?
Quoth siki ga...@karamaan.com,
The actual problem is quite similar to the one that I provided or to the one
in the description of the proposed extension that you linked.
Someone on another forum suggested record functions but I'm not sure I
understood correctly how that would work around this problem. Any suggestion
is greatly appreciated!
Maybe it was function records. That's kind of the poor man's OOP in
Haskell - no typeclasses needed.
data FileRec = FileRec {
fileRecRead :: Int - IO String
, fileRecWrite :: String - IO ()
}
socketFileRec socket = {
fileRecWrite = \ s - send socket s 0
, fileRecRead = \ i - recv socket i 0
}
pipeFileRec p0 p1 = {
fileRecWrite = writeFd p1
, fileRecRead = readFd p0
}
echoBlock file count = (fileRecRead file) count = fileRecWrite file
Maybe you could use that, maybe you couldn't. That's why Martin suggested
that you reveal the actual problem. Not the solution you had in mind,
but the thing you're trying to solve.
Donn
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[Haskell-cafe] createProcess problem
Hello, I am trying to use createProcess. Following is a small fragment. I am trying to run a program called blastall (a bio-informatics program). It is kind of like mv/cp/ln on Unix platforms (where the executable examines the program, i.e. arg[0], and then provides appropriate behavior/semantics). In the case of blastall, it alters its behavior based on the -p(program) CLI argument.WSo in the following it should provide nucleotide behavior ... that is what the 'n' on the end of blastn means. import System.Process main = do handle - runProcess blastall -- executable [-p blastn] -- CLI args Nothing-- optional cwd Nothing-- optional env Nothing-- optional stdin Nothing-- optional stdout Nothing-- optional stderr return () When I run this program with ghci, blastall is not a happy camper. It is complaining about -p blastn: [NULL_Caption] ERROR: Program name undefined: blastn the space between the double quote and 'b' is really there!!! [NULL_Caption] ERROR: Program name undefined: blastn Yet if I run 'blastall -p blastn' from the DOS prompt no errors(I will try tonight on my Linux machine). If I try 'blastall -p bozo from the DOS prompt I get the same two errors as when I run my test program using ghci. I feel that it has something to do with double quotes in Haskell ... probably something obviously silly that I am doing. Any ideas? Kind regards, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] createProcess problem
Hi Vasili, Vasili I. Galchin wrote: [snip] import System.Process main = do handle - runProcess blastall -- executable [-p blastn] -- CLI args Try: [-p, blastn] This passes multiple command line arguments instead of just one that contains a space. Most shells use spaces to separate arguments. [snip] Hope this helps, Claude -- http://claudiusmaximus.goto10.org ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] createProcess problem
On Mon, Apr 27, 2009 at 06:00:52PM -0500, Vasili I. Galchin wrote: I feel that it has something to do with double quotes in Haskell ... probably something obviously silly that I am doing. The problem is that [-p blastn] means that there's only one argument, while [-p, blastn] means what you want. In a Unix shell, what you're doing is the same as 'blastn -p blastn', which is clearly wrong. Why are things like this? Well, imagine that you wanted to pass a file as argument, and that file had a space in its name. Having a list of arguments leaves you unconcerned about these subtleties. -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Question about implementing an off-side rule in Parsec 2
I don't have experience solving this problem, but I've read a few horror stories from people who had state affect the results of parsing in Parsec. Haskell's layout rules replace indentation levels with braces and semicolons; you could run an initial tokenizing parser that builds tokens including the indentation level of each line, then convert those tokens into the appropriate braces and semicolons (via a pure function) before feeding the results into the real Haskell parser. -- ryan On Mon, Apr 27, 2009 at 2:41 PM, Bas van Gijzel neneko...@gmail.com wrote: Hello everyone, I'm doing a bachelor project focused on comparing parsers. One of the parser libraries I'm using is Parsec (2) and I'm going to implement a very small subset of haskell with it, with as most important feature the off-side rule (indentation based parsing) used in function definitions and possibly in where clauses. But I'm still a bit stuck on how to implement this cleanly. I tried to search for some examples on blogs but I haven't found anything yet. As far as I can see the way to go would be using getState and updateState methods defined in Parsec.Prim and to use the methods in Parsec.Pos to compare the difference in indendation for tokens. But I haven't completely wrapped my head around any state monad yet and I don't understand Parsec enough yet to see how to use the methods Parsec.Pos and state easily. Some examples or pointers to something to read would really be helpful. Thanks in advance, Bas van Gijzel ___ 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] createProcess problem
On Apr 27, 2009, at 18:55 , Vasili I. Galchin wrote: [-p blastn] -- CLI args createProcess expects a list of individual argument strings. You're sending it a single argument [-p blastn]; you want to send it two arguments [-p, blastn] (or [-pblastn] without the space; like most commands you can combine the parameter with the option or pass it as the next argument). The command line equivalent of what you're doing would be: blastall '- p blastn' -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Problem with installing phooey
When I try to install Phooey I get the following error: cabal install --constraint=Stream == 0.3 phooey Resolving dependencies... [1 of 1] Compiling Main ( /tmp/phooey-2.016943/phooey-2.0/Setup.lhs, /tmp/phooey-2.016943/phooey-2.0/dist/setup/Main.o ) Linking /tmp/phooey-2.016943/phooey-2.0/dist/setup/setup ... Configuring phooey-2.0... Warning: No 'build-type' specified. If you do not need a custom Setup.hs or ./configure script then use 'build-type: Simple'. Preprocessing library phooey-2.0... Building phooey-2.0... src/Graphics/UI/Phooey/WinEvents.hs:66:7: Could not find module `Data.Reactive': Use -v to see a list of the files searched for. It seems that the current version of reactive (0.10.5) no longer has Data.Reactive module (it seem to have been removed since 0.5 version of the reactive). Does Phooey really need 0.5 version of the reactive or is there a problem in my installation? Thanks Daryoush ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] LondonHUG talk: Engineering Large Projects in Haskell
Slides from last week's London HUG http://www.londonhug.net/ talk are now online. The talk attempts to document some of the tips and tricks Galois has accumulated using Haskell commercially for the past 10 years. You can now read the slides of the talk here: http://www.galois.com/blog/2009/04/27/engineering-large-projects-in-haskell-a-decade-of-fp-at-galois/ Cheers, Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
