Re: [Haskell-cafe] :Trace has no history
The debugger only instruments interpreted code, so evaluations occurring inside library code do not show up in :trace. This is not a terrible problem in practice, since usually seeing the evaluations occurring in your code is what you need to debug the problem. But since :trace is not showing you any evaluations at all, I wonder if the problem might be that your code is not interpreted. In order to ensure that it is, delete all the *.hi and *.o temporary files lying around. You can also simply invoke ghci with the -fbyte-code command line option. If that fails, please complete the paste of your session below with your invocation of ghci. There might be something else going on. Thanks, pepe On Wednesday, September 1, 2010, Steve Severance st...@medwizard.net wrote: How do I tell? Does this mean that if the exception is occurring in a haskell library I can't get to it? I am trying to run down a Prelude.read: No Parse error and I need to see the value that it is failing to parse on. Thanks. Steve On Tue, Aug 31, 2010 at 11:05 AM, Pepe Iborra pepeibo...@gmail.com wrote: Hi Steve The debugger only traces calls in interpreted code. Perhaps the call to myMethod is being made from object code? Admittedly, the ghci debugger can take some effort to learn to use properly. Make sure that you give a look to the ghc user guide if you haven't done so yet. Best, pepe On Tuesday, August 31, 2010, Steve sseve...@gmail.com wrote: I am trying to debug a problem in GHCI. I invoke my method with trace but when it breaks on exception i can't get this history. Output is below. Thanks. relude Symbols :set -fbreak-on-exception Prelude Symbols :trace myMethod Loading package HUnit-1.2.2.1 ... linking ... done. Loading package syb-0.1.0.2 ... linking ... done. Loading package base-3.0.3.2 ... linking ... done. Loading package old-locale-1.0.0.2 ... linking ... done. Loading package time-1.1.4 ... linking ... done. Loading package random-1.0.0.2 ... linking ... done. Loading package QuickCheck-1.2.0.0 ... linking ... done. Loading package Decimal-0.1.0 ... linking ... done. Loading package array-0.3.0.0 ... linking ... done. Loading package Diff-0.1.2 ... linking ... done. Loading package bytestring-0.9.1.5 ... linking ... done. Loading package containers-0.3.0.0 ... linking ... done. Loading package mtl-1.1.0.2 ... linking ... done. Loading package old-time-1.0.0.3 ... linking ... done. Loading package convertible-1.0.9 ... linking ... done. Loading package utf8-string-0.3.4 ... linking ... done. Loading package HDBC-2.2.6 ... linking ... done. Loading package HDBC-mysql-0.6.3 ... linking ... done. Loading package parsec-2.1.0.1 ... linking ... done. Loading package network-2.2.1.7 ... linking ... done. Loading package HTTP-4000.0.9 ... linking ... done. Loading package binary-0.5.0.2 ... linking ... done. Loading package digest-0.0.0.8 ... linking ... done. Loading package filepath-1.1.0.3 ... linking ... done. Loading package unix-2.4.0.0 ... linking ... done. Loading package directory-1.0.1.0 ... linking ... done. Loading package pretty-1.0.1.1 ... linking ... done. Loading package zlib-0.5.2.0 ... linking ... done. Loading package zip-archive-0.1.1.6 ... linking ... done. Loading package Core-0.0.1 ... linking ... done. Beginning Update Stopped at exception thrown _exception :: e = GHC.Exception.SomeException (GHC.Exception.D:Exception _ (GHC.Show.D:Show ...) ) (GHC.IO.Exception.IOError Nothing GHC.IO.Exception.UserError ) [exception thrown] Prelude Symbols :history Empty history. Perhaps you forgot to use :trace? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- José Iborra http://www.dsic.upv.es/~jiborra -- UPV Valencia Telf. (+34) 96 387 00 00 (ext) 83529 -- Camino de Vera s/n. 46022 Valencia (Spain) -- Steve Severance c. 240.472.9645 e. st...@medwizard.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- José Iborrahttp://www.dsic.upv.es/~jiborra -- UPV Valencia Telf. (+34) 96 387 00 00 (ext) 83529 -- Camino de Vera s/n. 46022 Valencia (Spain) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] :Trace has no history
Hi Steve The debugger only traces calls in interpreted code. Perhaps the call to myMethod is being made from object code? Admittedly, the ghci debugger can take some effort to learn to use properly. Make sure that you give a look to the ghc user guide if you haven't done so yet. Best, pepe On Tuesday, August 31, 2010, Steve sseve...@gmail.com wrote: I am trying to debug a problem in GHCI. I invoke my method with trace but when it breaks on exception i can't get this history. Output is below. Thanks. relude Symbols :set -fbreak-on-exception Prelude Symbols :trace myMethod Loading package HUnit-1.2.2.1 ... linking ... done. Loading package syb-0.1.0.2 ... linking ... done. Loading package base-3.0.3.2 ... linking ... done. Loading package old-locale-1.0.0.2 ... linking ... done. Loading package time-1.1.4 ... linking ... done. Loading package random-1.0.0.2 ... linking ... done. Loading package QuickCheck-1.2.0.0 ... linking ... done. Loading package Decimal-0.1.0 ... linking ... done. Loading package array-0.3.0.0 ... linking ... done. Loading package Diff-0.1.2 ... linking ... done. Loading package bytestring-0.9.1.5 ... linking ... done. Loading package containers-0.3.0.0 ... linking ... done. Loading package mtl-1.1.0.2 ... linking ... done. Loading package old-time-1.0.0.3 ... linking ... done. Loading package convertible-1.0.9 ... linking ... done. Loading package utf8-string-0.3.4 ... linking ... done. Loading package HDBC-2.2.6 ... linking ... done. Loading package HDBC-mysql-0.6.3 ... linking ... done. Loading package parsec-2.1.0.1 ... linking ... done. Loading package network-2.2.1.7 ... linking ... done. Loading package HTTP-4000.0.9 ... linking ... done. Loading package binary-0.5.0.2 ... linking ... done. Loading package digest-0.0.0.8 ... linking ... done. Loading package filepath-1.1.0.3 ... linking ... done. Loading package unix-2.4.0.0 ... linking ... done. Loading package directory-1.0.1.0 ... linking ... done. Loading package pretty-1.0.1.1 ... linking ... done. Loading package zlib-0.5.2.0 ... linking ... done. Loading package zip-archive-0.1.1.6 ... linking ... done. Loading package Core-0.0.1 ... linking ... done. Beginning Update Stopped at exception thrown _exception :: e = GHC.Exception.SomeException (GHC.Exception.D:Exception _ (GHC.Show.D:Show ...) ) (GHC.IO.Exception.IOError Nothing GHC.IO.Exception.UserError ) [exception thrown] Prelude Symbols :history Empty history. Perhaps you forgot to use :trace? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- José Iborrahttp://www.dsic.upv.es/~jiborra -- UPV Valencia Telf. (+34) 96 387 00 00 (ext) 83529 -- Camino de Vera s/n. 46022 Valencia (Spain) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] Woes on MacOS 10.6 - linking issues
(moving to the cafe) There is an incompatibility between the version of iconv in Mac Os and the one included in MacPorts. As the RTS of the build of ghc in the Haskell Platform is linked against Mac Os iconv, you cannot use it with the build of gtk2hs from MacPorts. This is a known issue already commented elsewhere, in case you haven't found it already: http://www.mail-archive.com/haskell-cafe@haskell.org/msg69139.html http://stackoverflow.com/questions/2726248/ghc-6-12-and-macports Cheers, On Fri, Jun 11, 2010 at 4:53 AM, Brett Giles brett.gi...@ucalgary.ca wrote: Hi Folks I seem to have Gtk2HS 0.11 installed, but not quite working. Interestingly, I can run a demo, such as the hello/World.hs example, directly in ghci. However, when I try to do a ghc --make on any code containing gtk2hs I get a link error like this: Undefined symbols: _iconv_close, referenced from: _hs_iconv_close in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_close) _iconv, referenced from: _hs_iconv in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_open, _hs_iconv , _hs_iconv_close ) _iconv_open, referenced from: _hs_iconv_open in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_open) ld: symbol(s) not found I do have libiconv installed as a universal library via macports. gtk, glade etc., are also universal installed via macports. I downloaded the OSX Haskell Platform package and am running ghc 6.12.1 Other programs seem to be having some issues as well though, For instance, a command line program seems to compile fine, but when it runs I get the message: $ emlqpl (--- My successfully compiled program - batch only, no gtk items) dyld: Library not loaded: /opt/local/lib/libgtk-quartz-2.0.0.dylib Referenced from: /usr/local/bin/emlqpl Reason: image not found Trace/BPT trap Does anyone have any suggestions? Brett Giles Grad Student, Formal Methods, Category Theory, University of Calgary brett.gi...@ucalgary.ca ___ Haskell mailing list hask...@haskell.org http://www.haskell.org/mailman/listinfo/haskell -- -- José Iborrahttp://www.dsic.upv.es/~jiborra -- UPV Valencia Telf. (+34) 96 387 00 00 (ext) 83529 -- Camino de Vera s/n. 46022 Valencia (Spain) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Associative Commutative Unification
On Fri, Jul 11, 2008 at 2:39 PM, John D. Ramsdell [EMAIL PROTECTED] wrote: Are you aware of Term Rewriting and all That? It describes how to do associative commutative unification; whether it satisfies your 'obviously correct' criterion I don't know. Oh yes, I know about term rewriting. If your equations can be expressed as a set of confluent rewrite rules, one can use the Martelli and Montanari's formalization of unification to come up with an obviously correct equational unifier. Alas, that simple trick doesn't work for AC unification. Have you heard of Maude? I hear the next version will have support for AC unification. If I stay with Haskell, I'd have to use their support via interprocess communication. Yuck. http://maude.cs.uiuc.edu/ John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe You are surely aware that AC unification is much more difficult than syntactical unification. CIMe[1] might be useful to solve the generated diophantine equations. But I don't think you will be able to obtain obvious correctness, and probably performance neither. I don't know what you are planning to do, but perhaps you'd be better served by Maude than by Haskell. The Maude language is a joy to use and version 2.4 with AC unification is (expectedly) being released next week in RTA. Cheers pepe [1] - http://cime.lri.fr/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] isWHNF :: a - IO Bool ?
Actually, in 6.8 we can build isWHNF on top of the GHC-API. First, you need to import the ghc package: ghci -package ghc GHCi, version 6.7: http://www.haskell.org/ghc/ :? for help Then, you can define the isWHNF function as follows: Prelude :m +RtClosureInspect Prelude RtClosureInspect let isWHNF = fmap (isConstr . tipe) . getClosureData Prelude RtClosureInspect :t isWHNF isWHNF :: a - IO Bool What the code above does is to inspect the info table associated to the value given, and check if the closure is a Constructor closure, i.e. in WHNF. We can put it to test now: Prelude RtClosureInspect let a = [1..10] Prelude RtClosureInspect isWHNF a False Prelude RtClosureInspect seq a () () Prelude RtClosureInspect isWHNF a True As a bonus because this code is included in GHC itself it should stay in sync with any changes in the GHC internal representations. Cheers pepe On 27/09/2007, at 14:51, Bernie Pope wrote: Hi Tristan, I've implemented it for earlier versions of GHC, by calling some C code which then peeps at the internal representation of a value. From memory, I needed to pass a stable pointer to the value to the C code, so that it can be polymorphic, without having to make it a primitive in GHC. Have a look at the reify code on this page: http:// www.cs.mu.oz.au/~bjpop/code.html - its more than what you want, but you can trim it down easily. Let me know if you get stuck. The internal representation in GHC tends to change between releases, so it might need a bit of polishing up. Cheers, Bernie. On 27/09/2007, at 10:07 PM, Tristan Allwood wrote: Hi, Does anyone know if there is a function that tells you if a haskell value has been forced or not? e.g. isWHNF :: a - IO Bool let x = (map succ [0..]) in do putStrLn . show (isWHNF x)-- False putStrLn . show . head $ x putStrLn . show (isWHNF x)-- True putStrLn . show (isWHNF (Just undefined)) -- True If not, would it be hard/easy/possible to implement on-top-of or using GHC? I'm happy (if it's possible) to have a stab at implementing it myself, so any pointers to right directions would be helpful. I'm thinking it could be useful to allow creation of sparse-check [1] like libraries without needing a separate logic encoding, or things along those lines / in that area. Cheers, Tris [1] http://www-users.cs.york.ac.uk/~mfn/sparsecheck/index.html#lim -- Tristan Allwood PhD Student Department of Computing Imperial College London ___ 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 mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] isWHNF :: a - IO Bool ?
Very cool. This is much nicer than when I asked much the same question a few years back (and I can think of all sorts of interesting things I can learn from the interface in that module). But what about indirection chasing? Surely we want isWHNF to return True if we have an indirection to a WHNF. Possibly one wants something a bit like this (untested, and rather depends on GHC's indirection semantics): removingIndirections :: (forall c . c - IO b) - a - IO b removingIndirections k a = do closureData - getClosureData a if isConstr (tipe closureData) then removingIndirections (ptrs closureData ! 0) else k a simpleIsWHNF :: a - IO Boolean simpleIsWHNF = fmap (isConstr . tipe) . getClosureData isWHNF = removingIndirections simpleIsWHNF Very true, isWHNF needs to follow indirections indeed. To decide whether to recurse, you probably intended to test for Indirections and not for Constructors: removingIndirections :: (forall c . c - IO b) - a - IO b removingIndirections k a = do closureData - getClosureData a if isIndirection (tipe closureData) then removingIndirections (ptrs closureData ! 0) else k a Thanks, pepe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Monad.Reader 8: Haskell, the new C++
On 13/09/2007, at 0:06, Don Stewart wrote: ok: In Monad.Reader 8, Conrad Parker shows how to solve the Instant Insanity puzzle in the Haskell type system. Along the way he demonstrates very clearly something that was implicit in Mark Jones' Type Classes with Functional Dependencies paper if you read it very very carefully (which I hadn't, but on re-reading it is there). That is, Haskell types plus multiparameter type classes plus functional dependencies is a logic programming language. In fact it is a sufficiently powerful language to emulate any Turing machine calculation as a type checking problem. So we have C++ : imperative language whose type system is a Turing-complete functional language (with rather twisted syntax) Haskell: functional language whose type system is a Turing- complete logic programming language (with rather twisted syntax) Since not all Turing machines halt, and since the halting problem is undecidable, this means not only that some Haskell programs will make the type checker loop forever, but that there is no possible meta- checker that could warn us when that would happen. I've been told that functional dependencies are old hat and there is now something better. I suspect that better here means worse. Better here means better -- a functional language on the type system, to type a functional language on the value level. -- Don For a taste, see Instant Insanity transliterated in this functional language: http://hpaste.org/2689 NB: it took me 5 minutes, and that was my first piece of coding ever with Type families ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Monad.Reader 8: Haskell, the new C++
For a taste, see Instant Insanity transliterated in this functional
language:
http://hpaste.org/2689
I thought I'd better paste here the code for Instant Insanity with
Type Families. Otherwise it will vanish in a short time.
I took the opportunity to clean it up a bit.
Although AT are not a supported feature, the code works in a 6.8.1
snapshot.
But note that you cannot actually see the solution, as there is no
way to ask
GHCi to display the normalized types.
My favorite bit is:
* type instance Map f Nil = Nil
* type instance Map f (x:::xs) = Apply f x ::: Map f xs
\begin{code}
import Prelude hiding (all, flip, map, filter)
u = undefined
data R -- Red
data G -- Green
data B -- Blue
data W -- White
data Cube u f r b l d
type CubeRed = Cube R R R R R R
type CubeBlue = Cube B B B B B B
type Cube1 = Cube B G W G B R
type Cube2 = Cube W G B W R R
type Cube3 = Cube G W R B R R
type Cube4 = Cube B R G G W W
data True
data False
type family And b1 b2
type instance And True True = True
type instance And True False= False
type instance And False True = False
type instance And False False= False
data Nil
data Cons x xs
data x ::: xs
infixr 5 :::
type family ListConcat l1 l2
type instance ListConcat Nil l = l
type instance ListConcat (x:::xs) ys = x:::(ListConcat xs ys)
type family Apply f a
data Rotation
data Twist
data Flip
type instance Apply Rotation (Cube u f r b l d) = Cube u r b l f d
type instance Apply Twist(Cube u f r b l d) = Cube f r u l d b
type instance Apply Flip (Cube u f r b l d) = Cube d l b r f u
type family Map f xs
type instance Map f Nil = Nil
type instance Map f (x:::xs) = Apply f x ::: Map f xs
type family Filter f xs
type instance Filter f Nil = Nil
type instance Filter f (x:::xs) = AppendIf (Apply f x) x (Filter f
xs)
type family AppendIf b x ys
type instance AppendIf True x ys = x ::: ys
type instance AppendIf False x ys = ys
type family MapAppend f xs
type instance MapAppend f Nil = Nil
type instance MapAppend f (x:::xs) = ListConcat (x:::xs) (Map f
(x:::xs))
type family MapAppend2 f xs
type instance MapAppend2 f Nil = Nil
type instance MapAppend2 f (x:::xs) = ListConcat (x:::xs)
(MapAppend f (Map f (x:::xs)))
type family MapAppend3 f xs
type instance MapAppend3 f Nil = Nil
type instance MapAppend3 f (x:::xs) = ListConcat xs (MapAppend2 f
(Map f (x:::xs)))
data Orientations
type instance Apply Orientations c = MapAppend3 Rotation (
MapAppend2 Twist (
MapAppend Flip (c:::Nil)))
type family NE x y
type instance NE R R = False
type instance NE R G = True
type instance NE R B = True
type instance NE R W = True
type instance NE G R = True
type instance NE G G = False
type instance NE G B = True
type instance NE G W = True
type instance NE B R = True
type instance NE B G = True
type instance NE B B = False
type instance NE B W = True
type instance NE W R = True
type instance NE W G = True
type instance NE W B = True
type instance NE W W = False
type family All l
type instance All Nil = True
type instance All (False ::: xs) = False
type instance All (True ::: xs) = All xs
type family Compatible c1 c2
type instance Compatible (Cube u1 f1 r1 b1 l1 d1) (Cube u2 f2 r2
b2 l2 d2) =
All (NE f1 f2 ::: NE r1 r2 ::: NE b1 b2 ::: NE l1 l2)
type family Allowed c cs
type instance Allowed c Nil = True
type instance Allowed c (y ::: ys) = And (Compatible c y) (Allowed
c ys)
type family Solutions cs
type instance Solutions Nil = (Nil ::: Nil)
type instance Solutions (c ::: cs) = AllowedCombinations (Apply
Orientations c) (Solutions cs)
type family AllowedCombinations os sols
type instance AllowedCombinations os Nil = Nil
type instance AllowedCombinations os (s ::: sols) =
ListConcat (AllowedCombinations os sols) (MatchingOrientations
os s)
type family MatchingOrientations os sol
type instance MatchingOrientations Nil sol = Nil
type instance MatchingOrientations (o ::: os) sol =
AppendIf (Allowed o sol) (o:::sol) (MatchingOrientations os sol)
type Cubes = (Cube1 ::: Cube2 ::: Cube3 ::: Cube4 ::: Nil)
solution = u :: Solutions Cubes
\end{code}
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Re: [Haskell-cafe] Weird ghci behaviour?
I can give the following partial explanation. When you run ghc test.hs it compiles your test file and produces some auxiliar files at the same time. When you run ghci afterwards, if the mod. date of the auxiliar files is more recent than that of the source file, it directly loads the object code form of the source file. So it appears that ghci is having trouble when loading the object code version. Whereas if it's not, it loads the module interpreted. Of course, if you remove test.hi, ghci will always load the file interpreted, and so the problem doesn't manifest. Cheers pepe On 20/07/2007, at 23:12, Dan Piponi wrote: On Unix-like OSes: If I run ghc test.hs and then run ghci test.hs, ghci fails to load up my code. I have to touch test.hs and then run ghci. I can understand ghci refusing to recompile something it thinks it has already compiled. But it appears to refuse to load it into an interactive session - which is less useful. In fact, removing test.hi makes ghci work again. This is ghc 6.6. Anyone else seeing this? -- Dan ___ 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] Practical Haskell question.
There is a related discussion, with a lot of pointers, in a recent D.Piponi blog post: http://sigfpe.blogspot.com/2007/04/homeland-security-threat-level- monad.html On 25/06/2007, at 10:58, peterv wrote: I'm baffled. So using the Arrow abstraction (which I don't know yet) would solve this problem? How can (perfectActionB x) be checked with without ever executing performActionA which evaluates to x? This can only be done when x is a constant expression no? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tomasz Zielonka Sent: Monday, June 25, 2007 10:43 AM To: Henning Thielemann Cc: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] Practical Haskell question. On Mon, Jun 25, 2007 at 10:29:14AM +0200, Henning Thielemann wrote: Imagine all performActions contain their checks somehow. Let performActionB take an argument. do x - performActionA y - performActionB x z - performActionC return $ calculateStuff x y z Now performActionB and its included check depend on x. That is, the check relies formally on the result of performActionA and thus check B must be performed after performActionA. IIUC, this limitation of Monads was one of the reasons why John Hughes introduced the new Arrow abstraction. Best regards Tomek ___ 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 mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Shim missing Distribution.Verbosity
Thanks for the report. That was an error I introduced in a previous patch, just pushed the fix. By the way, there is a Shim mailing list at http://shim.haskellco.de Cheers pepe On 11/06/2007, at 9:22, Johan Grönqvist wrote: Hi, I am trying to install shim (http://shim.haskellco.de/trac/wiki) on windows XP (GHC 6.6.1). When I run ./Setup.lhs build, ghc tells me that the module Distribution.Verbosity can not be found. The module is imported by Shim.GhcCompat. ghcii also tells me that Distribution.Verbosity can not be found. When I look at http://www.haskell.org/ghc/docs/latest/html/ libraries/index.html, I do not see Distribution.Verbosity there either. I have no idea how to proceed. Thanks for any help, Johan ___ 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] Haskell on OS X
MacPorts works fine here, and the maintainer, Gregory Wright, is very supportive. If it works for you, I really recommend MacPorts. The only downside are the lengthy compile times, but this is not a big deal, you can just leave it installing overnight. Carbon Emacs flavour here instead of Aqua, but for no reason in particular. I sweeten it with Haskell mode + shim. On 19/05/2007, at 20:27, Tom Harper wrote: I use Aquamacs with the haskell mode from haskell.org. MacPorts wasn't being useful with ghc, I downloaded binaries, and they work fine. On 5/19/07, Johan Tibell [EMAIL PROTECTED] wrote: I just switched to OS X and was wondering if someone would like to share their setup. Install binaries from haskell.org or Mac Ports? Which emacs build? etc Johan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Tom Harper Computer Science Major '07 Syracuse University +1 949 235 0185 Public Key: http://aftereternity.co.uk/rth.asc ___ 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] Disadvantages of de Bruijn indicies?
On 13/05/2007, at 12:44, Neil Mitchell wrote: Hi Thanks for all the responses, I'm busy reading through them. I'm still trying to decide whether I should use them or not. They complicate things, are less intuitive than names. But on the other hand, the language I'm working in is untyped and has only letrec. These things make binding errors easier to occur, and harder to detect. Thanks for the helpful throughts, Neil The Calculus of Indexed Names and Named Indices (CINNI) [1] looks really neat: The Calculus of Indexed Names and Named Indices (CINNI) is a new calculus of explicit substitutions that combines names and indices in a uniform way. It contains the standard named notation used in logics and programming languages as well as de'Bruijn's indexed notation as sublanguages. Disclaimer: I haven't read the Epigram paper nor Berkling, so I don't know how it compares. And I can't really talk from my own experience, since I have not played myself with CINNI yet. I wish I had a build-a- language assignment, just so that I could put CINNI to work... [1] - http://formal.cs.uiuc.edu/stehr/cinni_eng.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parallel executing of actions
On 16/04/2007, at 12:30, Mitar wrote:
Hi!
On 4/16/07, Bertram Felgenhauer
[EMAIL PROTECTED] wrote:
Since all the threads block on a single MVar how do they run in
parallel?
The idea is that before the threads block on the MVar, they run their
action x to completion.
The rendering crashes. I will have to precompute the values in threads
someway and then sequentially draw it? Any suggestion how to do that?
Could it be that you are launching 400x300=120.000 new threads all at
once?
If you are not doing it already, it would be sensible to implement
some pooling of threads.
This is what I use myself, don't worry about the unsafeness IF you
know that the sequence of computations doesn't matter:
\begin{code}
unsafeParMapM :: (a - IO b) - [a] - IO [b]
unsafeParMapM f = return . parMap rwhnf (unsafePerformIO . f)
unsafeParMapMn :: Integral bound = bound - (a - IO b) - [a] - IO
[b]
unsafeParMapMn max f xx = return (map (unsafePerformIO . f) xx
`using`
parListChunk (fromIntegral max) rwhnf)
unsafeParSeqn :: Integral bound = bound - [IO a] - IO [a]
unsafeParSeqn max cc = return ((map unsafePerformIO cc)
`using`
parListChunk (fromIntegral max) rwhnf)
\begin{code}
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Re: [Haskell-cafe] MPTC and type classes issue (polymorphic '+')
input2 = [ InputDecs [ inp emaLength TyNumber (20 + 40) ] ] (untested). Imho the simple, dumb, best fix for this is to give a explicit type to those values. input2 = [ InputDecs [ inp emaLength TyNumber ((20::Integer) + (40::Integer)) ] ] This is just one way to fix it. You could also try to improve your instances or enable -foverlapping-instances. But in my experience MPTC and overlapping instances, though powerful, can become very confusing, very quickly. Cheers pepe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Binary I/O
On 02/04/2007, at 16:26, Daniel Brownridge wrote: Hello. I am a Computer Science student attempting to write an emulator using Haskell. One of my main design choices is how to deal with machine code. Clearly it is possible to represent 0's and 1's as ASCII characters, however it strikes me that it would be much nicer to the I/O using raw binary. I don't seem to be able to find much documentation on this. Does anybody know how it's done, or can point me in the direction of some resources. Imho, just read directly to an Array and work with that. Probably you want to look at the OmegaGB Gameboy Emulator project for examples. http://www.mutantlemon.com/omegagb The code for loading ROM images to an Array of Words: http://darcs.mutantlemon.com/omegagb/src/RomImage.hs After that, opcodes are easily parsed by pattern matching on the hexadecimal values, e.g. see the mcti function in the Cpu module: http://darcs.mutantlemon.com/omegagb/src/Cpu.hs It would be nicer to write a Data.Binary instance for the Instruction datatype and use that to do the parsing, but I don't think that loading ROM files is a major speed concern here. Another interesting resource you may want to look at for your emulator code can be ICFPC'06 Universal Machine implementations. Don Stewart has a page with a few highly performant implementations (and there are benchmarks too, yay!): http://www.cse.unsw.edu.au/~dons/um.html Cheers pepe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parallelism on concurrent?
On 13/03/2007, at 17:46, Jefferson Heard wrote:
Simon will probably chime in on it as well, but his paper on the
subject is
the best there is:
http://research.microsoft.com/~simonpj/Papers/strategies.ps.gz
It does work in GHC 6.6 very nicely.
You can try it with the following naive fib function, extracted from
the paper mentioned above:
\begin{code}
import Control.Parallel
import System.Environment
import Fib
main = do
(x:_) - getArgs
print$ pfib (read x)
pfib 0 = 1
pfib 1 = 1
pfib n = n1 `par` n2 `seq` n1+n2+1
where (n1,n2) = (pfib(n-1), pfib(n-2))
\end{code}
pep:~/code/snippets/Parallelism$ ghc --make -O Main -threaded
pep:~/code/snippets/Parallelism$ time src/Main 33
11405773
real0m1.444s
user0m1.343s
sys 0m0.020s
pep:~/code/snippets/Parallelism$ time src/Main 33 +RTS -N2
11405773
real0m0.764s
user0m1.367s
sys 0m0.030s
Got a speedup of 100%, and didn't use threads at all. Yay!
pepe
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Re: [Haskell-cafe] Parallelism on concurrent?
Excuse me, I read too quick.
It works for forkIO too, although I'm not sure about forkOS. I don't
have a demo around, but you can verify with the concurrency demos in
the wiki:
http://haskell.org/haskellwiki/Concurrency_demos/Zeta
If it doesn't work, perhaps you are in an unsupported platform.
Cheers
pepe
On 13/03/2007, at 18:10, Dusan Kolar wrote:
Yes, it works for operator /par/. That's what I've reported. But
should it work for forkIO and forkOS? Could anybody give more
detailed answer than yes, no? :-) (Link to the Web is OK.)
BTW, thanks for the link to the paper (moreover, I can see, that
googling over haskell.org is not sufficient ;-) ).
Regards,
Dusan
Pepe Iborra wrote:
On 13/03/2007, at 17:46, Jefferson Heard wrote:
Simon will probably chime in on it as well, but his paper on the
subject is
the best there is:
http://research.microsoft.com/~simonpj/Papers/strategies.ps.gz
It does work in GHC 6.6 very nicely.
You can try it with the following naive fib function, extracted
from the paper mentioned above:
\begin{code}
import Control.Parallel
import System.Environment
import Fib
main = do
(x:_) - getArgs
print$ pfib (read x)
pfib 0 = 1
pfib 1 = 1
pfib n = n1 `par` n2 `seq` n1+n2+1
where (n1,n2) = (pfib(n-1), pfib(n-2))
\end{code}
pep:~/code/snippets/Parallelism$ ghc --make -O Main -threaded
pep:~/code/snippets/Parallelism$ time src/Main 33
11405773
real0m1.444s
user0m1.343s
sys 0m0.020s
pep:~/code/snippets/Parallelism$ time src/Main 33 +RTS -N2
11405773
real0m0.764s
user0m1.367s
sys 0m0.030s
Got a speedup of 100%, and didn't use threads at all. Yay!
pepe
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Re: [Haskell-cafe] Re: AT solution: rebinding = for restricted monads
Did anyone with knowledge of Associated Types pursue this solution?
Where did you get this from. My haskell-cafe mail folder doesn't seem
to have the thread you are replying to.
Sorry I replied from gmane; I should have included a link to the
original thread, but I really expected gmane to do that. The thread
is at:
http://www.haskell.org/pipermail/haskell-cafe/2006-December/020615.html
It doesn't work with GHC head, and I can't really do anything
about that.
Mostly curiosity.
The main reason this doesn't work with the head is because the
implementation of associated type *synonyms* (as opposed to associated
data types) is still incomplete. (See also
http://haskell.org/haskellwiki/GHC/Indexed_types.) We are
working at
the implementation, but I just relocated from New York to Sydney,
which
is why not much happened in the last two months.
But I also don't quite understand the intention of this code:
I will try to fill in the details, but surely it is all expanded in
the original thread.
The idea is that we have an indexed/effectful monad where bind and
return have a parameterized type:
class WitnessMonad m where
(=) :: m a b x - (x - m b c y) - m a c y
return :: x - m a a x
We can produce instances of WitnessMonad from an existing Monad using
an adaptor
newtype WitnessAdaptor m a b x = W {unW::m x}
instance Monad m = WitnessMonad (WitnessAdaptor m)
And rebind the do syntax to our WitnessMonad.
But using vanilla Monads via this trick requires to lift and unlift
every monadic action with the adaptor. An example in the IO monad:
test1 :: IO String
test1 = unW$ do
msg - W getLine
W$ putStrLn Thanks!
return msg
From here on the intent was on producing a solution using ATs that
hides this explicit wrapping. I don't really know the details of the
proposed solution.
Thanks
pepe
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Re: [Haskell-cafe] Safe lists with GADT's
I am really curious about this style of programming, and find myself
playing with it from time to time.
The example so far is very nice, but the funniest part is missing.
That is, defining appendL.
appendL :: List a t1 - List a t2 - List a t3
This says that the append of a list of length t1 and a list of length
t2 is a list of whatever length t3 we want. Obviously this is not
true and will not typecheck.
After some healthy days of reading papers and theses, I've found at
least three ways of defining it.
First, via existentials:
appendL1 :: List a t1 - List a t2 - exists t3. List a t3
Second, attaching a proof. Question: what would be the advantage of
the proof here?
data Add a b c where Base :: Add NilT a a ; Step :: Add a b c -
Add (ConsT a) b (ConsT c)
appendL2 :: List a t1 - List a t2 - exists t3. (Add t1 t2 t3,
List a t3)
Third, via Type Classes.
\begin{code}
class AddList a b c | a b - c
where append :: List x a - List x b - List x c
instance AddList NilT b b
where append Nil x = x
instance AddList a b c = AddList (ConsT a) b (ConsT c)
where append (Cons x l) l' = Cons x (append l l')
\end{code}
Given the three methods, I wouldn't know which one should be
preferred, and why.
In the first one you pay the burden of programming with existentials.
The second one in addition to that is the least efficient, as
building the proof surely has a cost. Since we are building it, isn't
there a way to use it to remove the existential?
Finally, with the third one your compiler will produce error messages
that will make you swear, apart from possible efficiency losses too.
Thanks for reading, any hints will be appreciated
pepe
On 26/02/2007, at 15:26, David Roundy wrote:
On Sun, Feb 25, 2007 at 10:40:13PM +, Neil Mitchell wrote:
data ConsT a
data NilT
data List a t where
Cons :: a - List a b - List a (ConsT b)
Nil :: List a NilT
...
Defining safeMap was trivial, but one thing I couldn't figure out was
how to write something like fromList:
fromList [] = Nil
fromList (a:as) = Cons a (fromList as)
fromList could obviously be anything such as reading from a file etc,
where the input is not known in advance. Are there any techniques for
this?
My favorite ways to wrap an existential is with another GADT:
data Existential a where Existential :: a b - a
(Yes, properly speaking this isn't a GADT, just an existential ADT,
but
it's easier for me to understand this way.)
Then
fromList [] = Existential Nil
fromList (a:as) = case fromList as of
Existential as' - Existential (Cons a as')
This is a pretty easy way to deal with the fromList. You'll now
also want
(which I don't think you mentioned in your example code) a GADT
version of
null, and perhaps other length operators:
data NullT t where
IsNull :: NullT NilT
NotNull :: NullT (ConsT t)
nullL :: List a t - NullT t
so you can now actually use your head function on a dynamically
generated
list, by running something like (e.g. in a monad)
do cs - readFile foo
Existential cs' - return $ fromList cs
-- note: we'll pattern-match fail on non-empty list here, which
-- may not gain much, we'd use case statements in reality, or
we'd
-- catch failure within the monad, which is also safe--
provided you
-- catch them, which the language doesn't force you to do!
(Or if
-- we're in a pure monad like Maybe.)
NotNull - nullL cs'
let c = headL cs'
t = tailL cs'
-- Now to illustrate the power of the GADT, a line that
will fail
-- at compile time:
t' = tailL t
return c
--
David Roundy
http://www.darcs.net
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[Haskell-cafe] Re: AT solution: rebinding = for restricted monads
David Roundy droundy at darcs.net writes: My latest attemp (which won't compile with the HEAD ghc that I just compiled, probably because I haven't figured out the synatax for guards with indexed types is: class WitnessMonad m where type W m :: * - * - * (=) :: (WitnessMonad m', WitnessMonad m'', w a b = W m', w b c = W m'', w a c = W m) = m' x - (x - m'' y) - m y () :: (WitnessMonad m', WitnessMonad m'', w a b = W m', w b c = W m'', w a c = W m) = m' x - m'' y - m y f g = f = const g return :: w a a = W m x = - m x fail :: String - m x data Witness a b instance Monad m = WitnessMonad m where W m = Witness () () (=) = Prelude.(=) () = Prelude.() return = Prelude.return fail = Prelude.fail which I think is quite pretty. It allows the Monadlike object to have kind * - *, while still allowing us to hide extra witness types inside and pull them out using the W function. Did anyone with knowledge of Associated Types pursue this solution? It doesn't work with GHC head, and I can't really do anything about that. Mostly curiosity. Thanks pepe Everything from here on is to convince GMane that, even if my message contains more quoted text than fresh text, it is a legitimate message and it should be ok to post it. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Looking for documentation on Control.Parallel.Strategies
There is also an excellent paper in tutorial style which imho is very useful to understand the interaction of lazyness with the Control.Parallel.Strategies combinators: Algorithm + Strategy = Parallelism Philip W. Trinder, Kevin Hammond, Hans-Wolfgang Loidl, and Simon L. Peyton Jones. Journal of Functional Programming, 8(1), Jan 1998. http://www.macs.hw.ac.uk/~dsg/gph/papers/abstracts/strategies.html On 16/02/2007, at 22:44, Jefferson Heard wrote: That's MUCH better, thanks. That's not what's directly available from haskell.org. It still doesn't give anything more general about using the combinators in actual programs, you know, like examples, but it's at least some clear documentation as to what each strategy does. Maybe one day, when I have a parallel program actually working, I could document that... On Friday 16 February 2007 16:26, Bjorn Bringert wrote: On Feb 16, 2007, at 21:16 , Jefferson Heard wrote: Is there anything that documents this further than the Haddock documentation available from Haskell.org or the GHC pages? I've gotten some basic parallelism to work using parMap and using || and |, but I had a fold and a map that I could logically compute at the same time. ... Maybe that's what you're looking at, but the darcs version has some more Haddock comments, see http://www.haskell.org/ghc/dist/current/ docs/libraries/base/Control-Parallel-Strategies.html /Björn ___ 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] Space Leak Help
hi Dominic Explicit recursion works just fine for me and keeps things simple: pad :: [Word8] - [Word8] pad xs = pad' xs 0 pad' (x:xs) l = x : pad' xs (succ l) pad' [] l = [0x80] ++ ps ++ lb where pl = (64-(l+9)) `mod` 64 ps = replicate pl 0x00 lb = i2osp 8 (8*l) at the cost of (very slightly) hiding data flow. Seems exactly what you were trying to avoid? Cheers pepe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ST and Transformers
Hi J Garrett, I don't see any problem in GHC 6.6. with: runTest c = runST (runErrorT c) *Main runTest (return True) Loading package mtl-1.0 ... linking ... done. Right True *Main On the other hand, I try to define it firstly as below and got the following error. runTest = runST . runErrorT Couldn't match expected type `forall t. Test t r' against inferred type `ErrorT e m a' Expected type: (forall t. Test t r) - forall s. ST s a1 Inferred type: ErrorT e m a - m (Either e a) In the second argument of `(.)', namely `runErrorT' In the expression: runST . runErrorT Rank-2 types seem to interact badly with (.) and ($), but my type theory educated neuron doesn't know why. I think this is folklore knowledge? Cheers pepe On 22/12/2006, at 18:26, J. Garrett Morris wrote: Hello everyone, I recently found myself attempting to use ST at the base of a stack of transformers, ala: type Test t r = ErrorT String (ST t) r I imagined, given the type of ST, that I would need a run function along the lines of: runTest :: (forall t. Test t r) - Either String r (which was, in fact, exactly what I wanted). Unfortunately, even with that type signature, I can't find a way to convince the compiler that the state thread is properly universal in the call to runST. Is it possible to write this function, or is ST (and other monads that use its style of threading) not transformable? Thanks, /g -- It is myself I have never met, whose face is pasted on the underside of my mind. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Composing monads (sort of)
Wait, there are two monads in scene here, IO and Maybe.
The right solution is to compose them indeed. One could use the
MaybeT monad transformer defined in the 'All about monads' tutorial
[1], or we could just define the IOmaybe monad:
import Data.Traversable (mapM)
newtype IOMaybe a = IOM { iom :: IO (Maybe a) }
instance Monad IOMaybe where
return = IOM . return . Just
c = f = IOM$ do
mb_v - iom c
mapM (iom.f) mb_v = return . join
Now we can define:
t1 = IOM . return . f1
t2 = IOM . f2
t3 = IOM . return . f3
traverse rec1 = t1 rec1 = t2 = t3
And this scheme lends itself very well to define any kind of traversal.
Note that I used the more general version of mapM defined in
Data.Traversable in the definition of the (=) combinator. A more
conventional definition is given the 'All about monads' tutorial.
Cheers
pepe
1- http://www.nomaware.com/monads/html/index.html
On 16/12/2006, at 15:35, Chris Eidhof wrote:
Hey Mark,
How can I concisely compose these functions without having to
write a cascade of case statements such as:
case f1 rec1 of
Nothing - return Nothing
Just id1 - do
rec2 - f2 id2
return $ case rec2 of
Nothing - return Nothing
Just rec2' - case f3 rec2' of
I understand that if I was just dealing with Maybe I could use the
fact that Maybe is a monad.
Yes, you can write like this:
id2 - f1 rec1
rec2 - f2 id2
rec3 - f3 rec2
return rec3
or, even shorter:
id2 - f1 rec1
rec2 - f2 id2
f3 rec2
The cool thing of the Maybe monad is that it combines a result in
such a way that it removes the plumbing of constantly checking for
Nothing. I can definitely recommand you the following tutorials:
http://www.nomaware.com/monads/html/index.html
http://uebb.cs.tu-berlin.de/~magr/pub/Transformers.en.html
Those two tutorials really helped me.
Good luck,
Chris
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Re: [Haskell-cafe] Refactoring recklessly
On 12/12/2006, at 20:31, Alec Berryman wrote: Greg Fitzgerald on 2006-12-12 11:24:58 -0800: I'd like to be able to reorganize my code and then verify that I didn't change any functionality. That is, the old and new code have precisely the same meaning. Also, I'd like to be able to change a function and verify that efficiency was the only thing affected. Are either of these possible in Haskell or any language? Use QuickCheck to generate parameters and compare return values for the old and the new functions. That is a great suggestion which works extremely well in my experience, but only for the second of Greg's requests. In the first case you don't need the additional validation, and probably you don't want to keep your unrefactored code around. ___ 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] Command line utility that shrinks/simplifies functions applications ?
On 30/11/2006, at 17:04, Spencer Janssen wrote: I believe you're talking about the `pl' plugin for lambdabot. Lambdabot has an offline mode, visit the homepage for the source: http://www.cse.unsw.edu.au/~dons/lambdabot.html There is also a web interface to lambdabot, but I can't seem to find the link. http://lambdabot.codersbase.com/ It's really nice, I use it all the time.___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] ANNOUNCE: Visual Haskell prerelease 0.2
On 28/11/2006, at 12:25, Krasimir Angelov wrote: On 11/28/06, Johannes Waldmann [EMAIL PROTECTED] wrote: seriously, how hard would it be to adapt VH to Eclipse? the interfaces (for syntax highlighting, typechecking etc.) should be similar - in theory. Parsing and typechecking in VH is all done by GHC via the ghc-api. Thus strong interoperability support is needed. Ah, and about Eclipse. Visual Studio and Eclipse are very different platforms and you have to rewrite VSHaskell almost from scratch if you want an Eclipse port. Perhaps the only common parts will be Cabal GHC. Not only the interfaces are completely different, but an entirely new set of interoperability problems would need to be solved. The guys from EclipseFP have a document[1] about that topic. That said I would love being able to run an eclipsified VH in my Mac :) [1] - http://eclipsefp.sourceforge.net/haskell/ ExtendingEclipseInHaskell.pdf Cheers pepe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Debugging
Can you manage to compile GHC under Windows? Compiling GHC under Windows is known to be a bit tricky and time consuming, certainly not for the novice user, although the steps are well detailed in the GHC developer documentation. If so, I'd encourage you to play with the Ghci Debugger project. But beware, it is still in an experimental phase and there are some pending issues. If you want to try it I have set up the repository to point to the last good known version I have around. Just follow the instructions on how to get the patches in the wiki page. Otherwise, I'd advise you to stick to Debug.Trace and friends. Cheers pepe On 13/11/2006, at 17:29, Valentin Gjorgjioski wrote: On 13.11.2006 16:54 Valentin Gjorgjioski wrote: On 13.11.2006 16:48 Pepe Iborra wrote: Hi Valentin Please, take a look at the Haskell Wiki page for debugging. http://haskell.org/haskellwiki/Debugging You will find that thanks to Neil Mitchell there is a Windows version of Hat available. Perhaps you can add your experiences with it if it works for you. Oh silly me, I was looking that page, but I didn't notice this. Thanks a lot, pepe. I'll try, and I'll post feedback here. I install it, I tried it, and it doesn't work for me. ./Hat/DML.hs:535:66: Ambiguous type variable `a' in the constraint: `Integral a' arising from use of `*^' at ./Hat/DML.hs:535:66-69 Probable fix: add a type signature that fixes these type variable(s) And this is line 535 T.uapp2 p125v94v125v148 p125v147v125v147 p (+^) (*^) After that, I have in my code used operator ^, and I deleted that operator. Program finally compiled, but now, hat-observe reports me an error... this program has encountered a problem So, I will be really happy with something simple as Hugs.Observe if it works with floats. Some recommendation please? Valentin ___ 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] Sistema de Ecuaciones NO lineales
hi Sebastian I think that it would be more appropriate to use english when you post to this particular list. On non linear equations or jacobi, I'm sorry but I cannot help you. But hopefully someone else in this list may be able to. Saludos. Cheers. pepe. On 09/11/2006, at 4:52, Sebastian Gaviria wrote: hola como estan Quiero preguntar quien puede resolver el sistemas de ecuaciones NO lineales de Newton y el codigo de Jacobi en Haskell me ayudarian mucho al poder implementar ese codigo por Favor es con urgencia tener estos codigos!! muchas gracias !!! -- La sociedad debe juzgarse por su capacidad para hacer que la gente sea feliz. SEBASTIAN GAVIRIA J. INGENIERIA SISTEMAS UNIVERSIDAD EAFIT ___ 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] Howto Haskell in PocketPC?
This has been around for some time already. It used to work with PPC2003, hopefully it'll still do: http://www.comp.nus.edu.sg/~luzm/ppchugs/ Enjoy it :) On 14/10/2006, at 8:24, Iván Pérez Domínguez wrote: Hi. Here a simple question: Is there any haskell compiler/interpreter or similar for PocketPC? ___ 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] how do you debug programs?
On 07/09/2006, at 10:53, Tamas K Papp wrote: Dear Pepe, Thank you for the information. I finally ended up working with Debug.Trace, and found the bug very quickly. I also tried Hood, but couldn't load it in ghci: import Observe can't find the library, but % locate Observe /usr/lib/ghc-6.4.2/hslibs-imports/util/Observe.hi /usr/lib/ghc-6.4.2/hslibs-imports/util/Observe.p_hi /usr/lib/hugs/libraries/Hugs/Observe.hs /usr/lib/hugs/oldlib/Observe.hs Does importing from hslibs-imports require something special? Hi Tamas I'm glad to hear that you fixed it! GHC includes Observe (the hs-libs-imports file you are seeing) only in the hidden 'util' package, which I believe is deprecated or not present in 6.6. If you want to use it, launch ghci with the flag '- package util'. Or download Observe.hs from the Hood website and place it somewhere in the path. Hmm, it would be handy to have a Cabal Hood package... Cheers pepe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] how do you debug programs?
Hi Tamas There are several ways to debug a Haskell program. The most advanced ones are based in offline analysis of traces, I think Hat [1] is the most up-to-date tool for this. There is a Windows port of Hat at [5]. Another approach is to simply use Debug.Trace. A more powerful alternative for this approach is Hood [2]. Even if it hasn't been updated in some time, Hood works perfectly with the current ghc distribution. Even more, Hugs has it already integrated [3]. You can simply import Observe and use observations directly in your program. For instance: import Observe f' = observe f f f a b = And then in hugs the expression: f' 1 2 would output what you want. Finally, the GHCi debugger project [4] aims to bring dynamic breakpoints and intermediate values observation to GHCi in a near future. Right now the tool is only available from the site as a modified version of GHC, so unfortunately you will have to compile it yourself if you want to try it. Cheers pepe 1. www.haskell.org/hat 2. www.haskell.org/hood 3. http://cvs.haskell.org/Hugs/pages/users_guide/observe.html 4. http://haskell.org/haskellwiki/GHC/GHCiDebugger 5. http://www-users.cs.york.ac.uk/~ndm/projects/windows.php On 06/09/06, Tamas K Papp [EMAIL PROTECTED] wrote: Hi, I would like to learn a reasonable way (ie how others do it) to debug programs in Haskell. Is it possible to see what's going on when a function is evaluated? Eg in f a b = let c = a+b d = a*b in c+d evaluating f 1 2 would output something like f called with values 1 2 c is now (+) a b = (+) 1 2 = 3 d is now (*) a b = (*) 1 2 = 2 ... Or maybe I am thinking the wrong way, and functional programming has its own debugging style... Thanks, Tamas ___ 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] how do you debug programs?
Thanks for the suggestion Don, I started the wiki page at http://haskell.org/haskellwiki/Debugging On 06/09/06, Donald Bruce Stewart [EMAIL PROTECTED] wrote: mnislaih: Hi Tamas There are several ways to debug a Haskell program. The most advanced ones are based in offline analysis of traces, I think Hat [1] is the most up-to-date tool for this. There is a Windows port of Hat at [5]. Another approach is to simply use Debug.Trace. A more powerful alternative for this approach is Hood [2]. Even if it hasn't been updated in some time, Hood works perfectly with the current ghc distribution. Even more, Hugs has it already integrated [3]. You can simply import Observe and use observations directly in your program. For instance: import Observe f' = observe f f f a b = And then in hugs the expression: f' 1 2 would output what you want. Finally, the GHCi debugger project [4] aims to bring dynamic breakpoints and intermediate values observation to GHCi in a near future. Right now the tool is only available from the site as a modified version of GHC, so unfortunately you will have to compile it yourself if you want to try it. Pepe, would you like to put up a page on the haskell.org wiki about debugging in Haskell? You could use the above mail as a start :) -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: how do you debug programs?
On 06/09/2006, at 17:10, Andrae Muys wrote:On 06/09/2006, at 8:22 PM, Neil Mitchell wrote:It's been my experience that debugging is a serious weakness ofHaskell - where even the poor mans printf debugging changes thesemantics! And everyone comes up with arguments why there is no needto debug a functional language - that sounds more like excuses aboutwhy we can't build a good lazy debugger :)[Sorry for the slight rant, but I've used Visual Studio C++ so I knowwhat a good debugger looks like, and how indispensable they are]I simply can't let this pass without comment. It's irrelevant if you're using a functional or imperative language, debuggers are invariably a waste of time. The only reason to use a debugger is because you need to inspect the contents of a processes address-space; so either you're using it as a disassembler, or you're using it to examine the consequences of heap/stack corruption. Consequently, if you're using Java, C#, Scheme, Haskell, Erlang, Smalltalk, or any one of a myriad of languages that don't permit direct memory access, there's no reason for you to be using a debugger.Jon understates it by implying this is a Functional/Haskell specific quality - it's not. Debuggers stopped being useful the day we finally delegated pointer handling to the compiler/vm author and got on with writing code that actually solves real problems.You seem to base everything on the assumption that a debugger is a program that lets you, and I quote your words below, "trace through individual lines of code".A debugger in the sense that this post regards it is any kind of program that helps you to understand a piece of code. A debugger is the program that tries to answer the following questions:"What information can we provide to the programmers about how a program is running?""What information will help the programmer most?"If it happens that traditionally debuggers are based in inspecting the memory, this is an unavoidable situation considering the history of programming languages. But certainly there are many other possibilities that can help a programmer to manage the complexity of a running program, and it seems as if you disregard them all completely in your argument !It's just that historically functional programmers have tended to already be experienced programmers who realise this. Why would they waste their time building a tool that no-one needs?This whole block is offensive to the rest of the world. Fortunately it has nothing to do with reality: - the recent GHC survey uncovered "some kind of debugger" as the most demanded tool - Other functional languages have seen magnificent efforts in the debugging camp, such as the awesome Ocaml debugger or the now sadly defunct ML Time-Travel debugger from A. Tolmach - The Lispish languages, which are arguably on the functional side too, have always enjoyed impressive online debugging tools.It's a truism to say if your code doesn't work it's because you don't understand it; clearly if you did understand it, you wouldn't have included the bug that's causing you difficulty.Therefore either1) The code is poorly structured and you need to restructure it to better represent your understanding of the problemor2) Your understanding of the problem is flawed, so you need to sit back and reexamine your thinking on this problem in light of the counter-example you have found (the bug).Spending your time tracing through individual lines of code is counter-productive in both cases.Andrae MuysP.S. It is worth noting that I am here talking about the sort of debugger raised in the original post. I am not talking about using a separate tool to extract a stracktrace from a core file in a C/C++ program or equivalent - I'm talking about runtime debugging with variable watches, breakpoints, and line-by-line stepping. -- Andrae Muys[EMAIL PROTECTED]Principal Kowari ConsultantNetymon Pty Ltd ___Haskell-Cafe mailing listHaskell-Cafe@haskell.orghttp://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] Why Haskell?
1) Lack of debugging support. Yes there are print statements and trace, but I would like to set a breakpoint. It would be nice to do so and launch the GHCi interpreter with all the variable context supported. A google search revealed that there is current work on this, but unfortunately the package is in cabal, which has spotty support in windows it seems. You can find more info about this project in the Haskell wiki at: http://haskell.org/haskellwiki/Ghci/Debugger All you'd need to do is to compile ghc-6.5 with a few patches (if you are in Windows you can use MinGW). But I am afraid you are right, this is a work in progress and we are in the process of polishing some serious issues right now. I can't really recommend it for now. Cheers pepe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[2]: [Haskell-cafe] Why Haskell?
Bulat, now that Krasimir has resumed work on Visual Haskell, I have planned to pursue an integration of the ghc-api debugger with Visual Haskell as soon as possible. But as we get closer to having dynamic breakpoints working 100%, the plain ghci debugging support starts to look as a fairly nice addition to anyone's ghc toolkit. Of course, I agree with you that it's too early to recommend it for real work. On 23/07/06, Bulat Ziganshin [EMAIL PROTECTED] wrote: Hello Pepe, Sunday, July 23, 2006, 5:23:18 PM, you wrote: 1) Lack of debugging support. Yes there are print statements and trace, You can find more info about this project in the Haskell wiki at: http://haskell.org/haskellwiki/Ghci/Debugger All you'd need to do is to compile ghc-6.5 with a few patches (if you are in Windows you can use MinGW). But I am afraid you are right, this is a work in progress and we are in the process of polishing some serious issues right now. I can't really recommend it for now. is this will be really usable without gui support? your project is really great, but i think it's too early to recommend it for real work (as opposite to hacking/integration with IDEs) -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Google SoC
http://code.google.com/soc/ This is not news. SoC was presented a few days ago, and by now there are a lot of projects available, yet none(?) Haskell related :( This is a plea for Haskell FOSS project managers to apply as mentor organizations, so that we students can have a choice. Surely there are a lot of contributions that can be tackled by a motivated student in three months time. GHC related stuff, work in Visual Haskell, tasks in a given Haskell framework, Darcs stuff, you name it. Deadline for mentor organizations is May 1, but they might close it earlier if they get their hands full. pep ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: EclipseFP (Haskell IDE) 0.9.1 released
Graham Klyne [EMAIL PROTECTED] escribió en el mensaje news:[EMAIL PROTECTED] One of the features of Haskell that I like is that it doesn't require lots of IDE support to write complex programs... the compact syntax and clean separation of concerns that can be achieved make it iasy enough to program using nothing more than a regular text editor, and no long wait for the development environment to start up. I can imagine programming Haskell on a palm-top device. I do that on my PDA phone sometimes, usually when I'm having a coffee with some buddy discussing this or that algorithm :) Thanks to whoever ported Hugs for Windows CE (I don't remember the url now) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
