GHCI segfault on Double math
I'm trying to see if this is reproducible, or it's just my machine. I'm on a MacBook Pro (15-inch, Mid 2012), OS X 10.8.2, Haskell Platform 2012.4.0.0 (32 bit): $ ghci GHCi, version 7.4.2: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude properFraction (-1.1 :: Float) (-1,-0.10024) Prelude properFraction (1.1 :: Double) (1,0.10009) Prelude properFraction (-1.1 :: Double) (-1,Segmentation fault: 11 'ceiling' and other code that uses properFraction segfaults on negative doubles, too. Compiled code doesn't have this defect. I'm going to try the 64 bit version to see if it resolves this problem. -Ron Alford ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: More infinite simplifier bugs?
On Fri, Jul 6, 2012 at 7:18 AM, Simon Peyton-Jones simo...@microsoft.com wrote: try with -ddump-rule-firings -dverbose-core2core -ddump-occur-anal -ddump-inlinings. You'll get a lot of output ,but you may either see (a) output stops but computer gets hot, (b) output goes on and on. use HEAD if you can Thanks. I haven't set HEAD up yet, but for 7.4.2, (b) appears to be the case (the function pddlDocExpr appears in the output quite often). I'm still trying to whittle down my program to a small test case, but even small and seemingly irrelevant changes are enough to restore GHC's termination. -Ron Alford ghcloop.hs Description: Binary data ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
More infinite simplifier bugs?
So a while back Simon added a tick counter to the simplifier: http://hackage.haskell.org/trac/ghc/ticket/5448 Are there any known bugs that can cause the simplifier to run out of memory /without/ hitting the tick counter limit? I have code that /used/ to run (at least after hacking around the previous simplifier bug): https://github.com/ronwalf/Planning With GHC 7.4.[12], it exhausts all the RAM on my machine (4GB). Compiling with -O0 fixes the problem. I can start bisecting my code to find the problem if nothing comes to mind. -Ron Alford (who seems to be good at killing the simplifier) ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Inliner non-termination
From the known bugs
(http://www.haskell.org/ghc/docs/latest/html/users_guide/bugs.html#bugs-ghc):
GHC's inliner can be persuaded into non-termination using the
standard way to encode recursion via a data type...
We have never found another class of programs, other than this
contrived one, that makes GHC diverge, and fixing the problem would
impose an extra overhead on every compilation. So the bug remains
un-fixed.
There are now three more examples, at least two of which weren't 'contrived':
http://hackage.haskell.org/trac/ghc/ticket/5448
http://hackage.haskell.org/trac/ghc/ticket/5400
http://hackage.haskell.org/trac/ghc/ticket/3872
It took me about 4-6 hours to track down this bug in my own code
(#5448) since it required repeatedly bisecting a larger program until
I had a small testcase. In the test program, I can get around it with
{-# NOINLINE funcEq #-}. In the program it came from, though, FuncEq
is an imported value, so I have to either compile with -O0, or change
put the pragma in the imported library, where it will effect a fair
amount of code that /doesn't/ hit this bug.
If adding the check is too expensive, can the inliner have a
configurable recursion bount (ala -fcontext-stack)?
-Ron Alford
___
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Inliner non-termination
On Tue, Sep 6, 2011 at 7:50 PM, Felipe Almeida Lessa
felipe.le...@gmail.com wrote:
This doesn't solve GHC's bug, but can you do something like
myFuncEq = funcEq
{-# NOINLINE myFuncEq #-}
and just use myFuncEq everywhere? This should make the change local
to your module.
Unfortunately not. The only time I use funcEq in the code in question
is the instance declaration.
-Ron Alford
___
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: [Haskell-cafe] Re: How does one get off haskell?
On Fri, Jun 18, 2010 at 10:30 AM, C. McCann c...@uptoisomorphism.net wrote: The better question is when do the benefits of static typing outweigh the costs imposed?. If you're using Java, the answer is probably never, but even in Haskell I don't think the answer is quite always. I have half a concrete example! I do research in automated planning, and the standard problem definition language is PDDL[1]. PDDL uses FOL logic expressions for expressing goal conditions, action preconditions, effects and various other things. The problem comes in that it uses a /different/ subset of first-order logic for each expression, leading to something like 8 or so expression types contained just in PDDL 3.1 (the latest 'standard'). Then there are the many previous versions of PDDL, and all the many extensions and subset/extensions to various versions of PDDL used in other people's research projects. So, when I wrote a PDDL library to help with my research, I needed extensibility. If not, I'd need to either fork the library for every PDDL extension, or create some sort of uber-PDDL which contained all the extensions. The best I came up with is Wouter's Datatypes a la Carte [2] which I used along with an extensible record technique my implementation[3]*. There are downsides to this approach. The most obvious is that to define a function over one of these datatypes, you need to define a class associated with that function and then define an instance of that class for every component. Also, type signatures are huge and I feeling like I'm using half the language extensions out there. I end up with a full complement of boilerplate code, and it doesn't even buy me full expression type safety (there are restrictions in PDDL on how expressions combine). Now, one thing I'm missing out of this example is the other side of the coin - doing it better in a dynamically typed language. However, there are plenty of C, lisp, and python PDDL planners out there, and I'm pretty sure they don't bother with type safe expressions. Also, this isn't an indictment of static typing in general. This only shows that my task isn't well suited to Haskell's current static typing. -Ron Alford * Note that this was my first and only real haskell project, and all that this entails. [1] http://en.wikipedia.org/wiki/Planning_Domain_Definition_Language [2] http://lambda-the-ultimate.org/node/2700 [3] http://www.cs.umd.edu/projects/planning/data/alford09translating/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Interest in a Mathematics AI strike force ?
On Wed, May 5, 2010 at 12:10 PM, Neal Alexander relapse@gmx.com wrote: - Goal Oriented Behaviors (work in progress) - Goal Oriented Planning (work in progress) I have a library for PDDL parsing and representation[1] that I used in a recent paper. It's heavy complex types to deal with various extensions to the language. I'm currently updating it for another project, so if you're interested, please let me know! -Ron [1] http://www.cs.umd.edu/projects/planning/data/alford09translating/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Deriving regression or bad code?
I was getting a similar error with standalone deriving (already attached to that bug), but I didn't try it through-out. I'll let you know how it goes. -Ron On Mon, Apr 12, 2010 at 6:01 AM, Simon Peyton-Jones simo...@microsoft.com wrote: It's really a bug. I've fixed it in my tree, but I'm at 2.8 and don't have time to validate etc. So I'm doubtful that I'll be in time to get a fix into 6.12.1, alas. Well, maybe I can build a patch and send it to Simon/Ian for testing. I'll try to do that if it's important to you. it's bit of an exotic case because of the higher-kindedness so I don't think it'll bite too man people There's a good workaround: use standalone deriving. You | -Original Message- | From: glasgow-haskell-users-boun...@haskell.org [mailto:glasgow-haskell- | users-boun...@haskell.org] On Behalf Of Ron Alford | Sent: 10 April 2010 22:33 | To: glasgow-haskell-users | Subject: Re: Deriving regression or bad code? | | Just for fun, I tried it on 6.12.1.20100330 with the same result. | Does anyone have a workaround? Otherwise I need to revert to 6.10. | | -Ron | | On Thu, Apr 8, 2010 at 10:35 AM, Ron Alford ronw...@volus.net wrote: | At Igloo's suggestion, it's now a ticket: | http://hackage.haskell.org/trac/ghc/ticket/3965 | | -Ron | | On Thu, Apr 8, 2010 at 1:39 AM, Ron Alford ronw...@volus.net wrote: | I've attached the simplest example of my code that used to compile in | GHC 6.10 now gives the error in GHC 6.12.1: | ... | | ___ | Glasgow-haskell-users mailing list | Glasgow-haskell-users@haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Deriving regression or bad code?
Just for fun, I tried it on 6.12.1.20100330 with the same result. Does anyone have a workaround? Otherwise I need to revert to 6.10. -Ron On Thu, Apr 8, 2010 at 10:35 AM, Ron Alford ronw...@volus.net wrote: At Igloo's suggestion, it's now a ticket: http://hackage.haskell.org/trac/ghc/ticket/3965 -Ron On Thu, Apr 8, 2010 at 1:39 AM, Ron Alford ronw...@volus.net wrote: I've attached the simplest example of my code that used to compile in GHC 6.10 now gives the error in GHC 6.12.1: ... ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Deriving regression or bad code?
At Igloo's suggestion, it's now a ticket: http://hackage.haskell.org/trac/ghc/ticket/3965 -Ron On Thu, Apr 8, 2010 at 1:39 AM, Ron Alford ronw...@volus.net wrote: I've attached the simplest example of my code that used to compile in GHC 6.10 now gives the error in GHC 6.12.1: ... ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Deriving regression or bad code?
I've attached the simplest example of my code that used to compile in GHC 6.10 now gives the error in GHC 6.12.1: baddata.hs:33:14: No instances for (Data Const, Data Var) arising from the 'deriving' clause of a data type declaration at baddata.hs:33:14-17 Possible fix: add an instance declaration for (Data Const, Data Var) or use a standalone 'deriving instance' declaration instead, so you can specify the instance context yourself When deriving the instance for (Data (Domain e g)) If I replace: data Domain e g = Domain (Expr (Const :+: Var)) deriving (Data, Typeable) with: data Domain e g = Domain (Expr (Const)) deriving (Data, Typeable) then everything compiles. If nothing else, the error message is misleading. -Ron baddata.hs Description: Binary data ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: [Haskell-cafe] GHC Error: FATAL:Symbol _XJv_srt already defined.
I reopened the bug, since I found slight changes to the file were able to reproduce the bug in recent versions of ghc-6.9. I also can't get the -S compilation step to work with the new file, unless I'm missing a step. -Ron Alford On Mon, Jul 21, 2008 at 3:32 AM, Ron Alford [EMAIL PROTECTED] wrote: Oops, already posted the bug: http://hackage.haskell.org/trac/ghc/ticket/2456 On Mon, Jul 21, 2008 at 3:29 AM, Austin Seipp [EMAIL PROTECTED] wrote: Status update: after checking out the latest HEAD and building it, the above error does not occur: $ ~/ghc-head/bin/ghc --version The Glorious Glasgow Haskell Compilation System, version 6.9.20080720 $ ~/ghc-head/bin/ghc --make DerivingError.hs no location info: Warning: -fallow-overlapping-instances is deprecated: Use the OverlappingInstances language instead [1 of 1] Compiling DerivingError( DerivingError.hs, DerivingError.o ) $ However, this doesn't exactly help your immediate problem, and it likely won't until 6.10.1 is released, as 6.8.3 is going to be the last release of the 6.8 branch. Truly sorry I couldn't have helped you more. Austin ___ 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
GHC Error: FATAL:Symbol _XJv_srt already defined.
I posted this to Haskell-Cafe, but it's more GHC specific. Anyone know what this is about? Removing parts makes problem go away, but it's not clear what parts to remove! (that, and I wrote those parts for a reason!). bash-3.2$ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.8.3 bash-3.2$ uname -a Darwin silverback-wired.home 9.4.0 Darwin Kernel Version 9.4.0: Mon Jun 9 19:30:53 PDT 2008; root:xnu-1228.5.20~1/RELEASE_I386 i386 $ rm -f DerivingError.o DerivingError.hi; ghc --make DerivingError.hs [1 of 1] Compiling DerivingError( DerivingError.hs, DerivingError.o ) /var/folders/C0/C0SledGV2RaxbU+8ZLDnVU+++TI/-Tmp-//ghc27223_0/ghc27223_0.s:6080:0: FATAL:Symbol _XxG_srt already defined. -Ron Alford DerivingError.hs Description: Binary data ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
[Haskell-cafe] GHC Error: FATAL:Symbol _XJv_srt already defined.
Anyone know what this is about? Removing parts makes problem go away, but it's not clear what parts to remove! (that, and I wrote those parts for a reason!). bash-3.2$ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.8.3 bash-3.2$ uname -a Darwin silverback-wired.home 9.4.0 Darwin Kernel Version 9.4.0: Mon Jun 9 19:30:53 PDT 2008; root:xnu-1228.5.20~1/RELEASE_I386 i386 $ rm -f DerivingError.o DerivingError.hi; ghc --make DerivingError.hs [1 of 1] Compiling DerivingError( DerivingError.hs, DerivingError.o ) /var/folders/C0/C0SledGV2RaxbU+8ZLDnVU+++TI/-Tmp-//ghc27223_0/ghc27223_0.s:6080:0: FATAL:Symbol _XxG_srt already defined. -Ron Alford DerivingError.hs Description: Binary data ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Typeable and fancy types
Hey all, I've reduced my previous problem to a small example. Anyone know why typeOf (...) would work, but typeOf [...] would not? Is the derivation for lists funky? data Expr f = In (f (Expr f)) instance Typeable1 f = Typeable (Expr f) where typeOf (In x) = mkTyConApp (mkTyCon TypeTest.Expr) [typeOf1 x] data Foo e = Foo deriving instance Typeable1 Foo *TypeTest typeOf (In Foo) TypeTest.Expr TypeTest.Foo *TypeTest typeOf [In Foo] *** Exception: Prelude.undefined TypeTest.hs Description: Binary data ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Combining Wouter's expressions with extensible records
On Fri, Jul 11, 2008 at 12:50 PM, Antoine Latter [EMAIL PROTECTED] wrote: Now we never do pattern matching on our input. This has been pretty educational. Mightily! I'll have to do the same trick for Expr. Thank you very much! -Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Combining Wouter's expressions with extensible records
On Wed, Jul 9, 2008 at 11:01 PM, Antoine Latter [EMAIL PROTECTED] wrote: It isn't immediately obvious to me that the Typeable family of classes deal at all with higher-kinded type constructors, but I didn't look that hard. Yes, that's what I'm worried about. For people's fun and amusement, I've attached the file. The trailing comments show what I'm trying to accomplish (getName, setName, and so forth). -Ron WouterTest.hs Description: Binary data ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Combining Wouter's expressions with extensible records
Or, if people have easy-enough extensible records that /will/ work with funky types, I'd be happy to use those! -Ron On Thu, Jul 10, 2008 at 10:29 AM, Ron Alford [EMAIL PROTECTED] wrote: On Wed, Jul 9, 2008 at 11:01 PM, Antoine Latter [EMAIL PROTECTED] wrote: It isn't immediately obvious to me that the Typeable family of classes deal at all with higher-kinded type constructors, but I didn't look that hard. Yes, that's what I'm worried about. For people's fun and amusement, I've attached the file. The trailing comments show what I'm trying to accomplish (getName, setName, and so forth). -Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Data.Derive problems
I'm using GHC 6.8.3 with $ cabal --version cabal-install version 0.5.1 using version 1.4.0.1 of the Cabal library I installed Data.Derive from hackage, only to be unable to find the 'derive' binary! Trying it directly from darcs, I get: $ ghc --make Setup.hs [1 of 1] Compiling Main ( Setup.hs, Setup.o ) Linking Setup ... silverback-wired:derive ronwalf$ ./Setup configure Warning: defaultUserHooks in Setup script is deprecated. Configuring derive-0.1.1... Warning: No 'build-type' specified. If you do not need a custom Setup.hs or ./configure script then use 'build-type: Simple'. -Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Combining Wouter's expressions with extensible records
I'm making progress, but how would I make the following a Typeable instance: data (f :+: g) e = Inl (f e) | Inr (g e) deriving Eq Here is what I'm using for Expr: data Expr f = In (f (Expr f)) instance Typeable1 f = Typeable (Expr f) where typeOf (In x) = mkTyConApp (mkTyCon Data.Trie.General.ListGT) [typeOf1 x] I don't think I can use this for ':+:', because the typeOf instance only has access to a member of one type at a time. This may be similar to a definition of Typeable2 for Either, but I can't find an example to follow for that. Thanks, -Ron On Wed, Jul 9, 2008 at 10:40 PM, Ron Alford [EMAIL PROTECTED] wrote: Well, my extension of Wouter's datatypes proved to be unweildy So, I'm trying to use http://fmapfixreturn.wordpress.com/2008/05/03/simple-extensible-records-now-quick-generic-tricks-pt-1/ for extensible records. I ran across my first problem rather quickly! data Expr f = In (f (Expr f)) Ok, but to make it part of a record, it needs to implement Data: data Expr f = In (f (Expr f)) deriving Data but this gives No instances for (Data (f (Expr f)), Typeable (Expr f)) arising from the 'deriving' clause of a data type declaration at Planning/Wouter.hs:77:0-42 Any hints? Thanks, -Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Derive problems
On Thu, Jul 10, 2008 at 3:18 PM, Neil Mitchell [EMAIL PROTECTED] wrote: Hi Ron, I'm using GHC 6.8.3 with $ cabal --version cabal-install version 0.5.1 using version 1.4.0.1 of the Cabal library I installed Data.Derive from hackage, only to be unable to find the 'derive' binary! Did you do the runhaskell Setup configure runhaskell Setup build runhaskell Setup install? I used 'sudo cabal install derive'. I did find the binary - in my user's .cabal/bin directory! Odd that it should default to that when run as root. I don't have the darcs version working yet, though. -Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Combining Wouter's expressions with extensible records
Close - it compiles now! I made a minor change, going to Typeable1 instead of Typeable: instance (Typeable1 f, Typeable1 g) = Typeable1 (f :+: g) where typeOf1 l@(Inl x) = mkTyConApp (mkTyCon Planning.Wouter.:+:) [typeOf1 x, typeOf1 y] where (Inr y) = undefined `asTypeOf` l typeOf1 r@(Inr y) = mkTyConApp (mkTyCon Planning.Wouter.:+:) [typeOf1 x, typeOf1 y] where (Inl x) = undefined `asTypeOf` r Except this gives me a runtime error: *WouterTest getName testNamed *** Exception: Prelude.undefined The only thing I can think of is to have a class that gives default values to type - ick! -Ron Alford On Thu, Jul 10, 2008 at 4:16 PM, Antoine Latter [EMAIL PROTECTED] wrote: On Thu, Jul 10, 2008 at 2:15 PM, Ron Alford [EMAIL PROTECTED] wrote: I'm making progress, but how would I make the following a Typeable instance: data (f :+: g) e = Inl (f e) | Inr (g e) deriving Eq Here is what I'm using for Expr: data Expr f = In (f (Expr f)) instance Typeable1 f = Typeable (Expr f) where typeOf (In x) = mkTyConApp (mkTyCon Data.Trie.General.ListGT) [typeOf1 x] I don't think I can use this for ':+:', because the typeOf instance only has access to a member of one type at a time. This may be similar to a definition of Typeable2 for Either, but I can't find an example to follow for that. Maybe something like: instance (Typeable1 f, Typeable1 g) = Typeable (f :+: g) where typeOf in@(InL f) = (some function of 'f' and 'g') where InR g = undefined `asTypeOf` in typeOf in@(InR g) = (some function of 'f' and 'g') where InL f = undefined `asTypeOf` in would work? -Antoine WouterTest.hs Description: Binary data ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Combining Wouter's expressions with extensible records
This is a bit similar to Either. Is there a way to see the generated instance code for deriving instance Data Either ? On Thu, Jul 10, 2008 at 6:38 PM, Ron Alford [EMAIL PROTECTED] wrote: Close - it compiles now! I made a minor change, going to Typeable1 instead of Typeable: instance (Typeable1 f, Typeable1 g) = Typeable1 (f :+: g) where typeOf1 l@(Inl x) = mkTyConApp (mkTyCon Planning.Wouter.:+:) [typeOf1 x, typeOf1 y] where (Inr y) = undefined `asTypeOf` l typeOf1 r@(Inr y) = mkTyConApp (mkTyCon Planning.Wouter.:+:) [typeOf1 x, typeOf1 y] where (Inl x) = undefined `asTypeOf` r Except this gives me a runtime error: *WouterTest getName testNamed *** Exception: Prelude.undefined The only thing I can think of is to have a class that gives default values to type - ick! -Ron Alford On Thu, Jul 10, 2008 at 4:16 PM, Antoine Latter [EMAIL PROTECTED] wrote: On Thu, Jul 10, 2008 at 2:15 PM, Ron Alford [EMAIL PROTECTED] wrote: I'm making progress, but how would I make the following a Typeable instance: data (f :+: g) e = Inl (f e) | Inr (g e) deriving Eq Here is what I'm using for Expr: data Expr f = In (f (Expr f)) instance Typeable1 f = Typeable (Expr f) where typeOf (In x) = mkTyConApp (mkTyCon Data.Trie.General.ListGT) [typeOf1 x] I don't think I can use this for ':+:', because the typeOf instance only has access to a member of one type at a time. This may be similar to a definition of Typeable2 for Either, but I can't find an example to follow for that. Maybe something like: instance (Typeable1 f, Typeable1 g) = Typeable (f :+: g) where typeOf in@(InL f) = (some function of 'f' and 'g') where InR g = undefined `asTypeOf` in typeOf in@(InR g) = (some function of 'f' and 'g') where InL f = undefined `asTypeOf` in would work? -Antoine ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Combining Wouter's expressions with extensible records
Ok, I'm closer, but I'm running into a problem with typeOf and lists, of all things: *WouterTest typeOf (eVar v :: TermExpr) Planning.Wouter.Expr (Planning.Wouter.:+: WouterTest.Const WouterTest.Var) *WouterTest typeOf ([eVar v] :: [TermExpr]) *** Exception: Prelude.undefined I'm pretty sure this is the culprit for getName: *WouterTest getName testNamed *** Exception: Prelude.undefined Any hints? Also, anyone have hints for how to get automatic derivation of Data (Expr f) ? I don't want to proliferate the last lines: deriving instance Data (Expr (And :+: Atomic (Expr (Const :+: Var deriving instance Data (Expr (Const :+: Var)) -Ron Alford WouterTest.hs Description: Binary data ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Combining Wouter's expressions with extensible records
Well, my extension of Wouter's datatypes proved to be unweildy So, I'm trying to use http://fmapfixreturn.wordpress.com/2008/05/03/simple-extensible-records-now-quick-generic-tricks-pt-1/ for extensible records. I ran across my first problem rather quickly! data Expr f = In (f (Expr f)) Ok, but to make it part of a record, it needs to implement Data: data Expr f = In (f (Expr f)) deriving Data but this gives No instances for (Data (f (Expr f)), Typeable (Expr f)) arising from the 'deriving' clause of a data type declaration at Planning/Wouter.hs:77:0-42 Any hints? Thanks, -Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Wouter Swierstra style extensible records!
Having made over-use of Wouter's expression idioms, I decided to hack it into extensible records. It's not documented, it's probably got holes in its usability, but I thought I'd post it so people can play with it (and give suggestions before I rewrite my code to use it!). I know there are other extensible record systems, but I wondered how this stacks up. Notably, it looks like in HList the records are only extensible in one direction (tacking fields onto the end), although they have a much more developed syntax (if you're into that sort of thing). Current problems: * Defining a new field is rather bulky - currently it takes lines. Definitions are bulky in Wouter's extensible expressions, too, but I could probably shorten the get/set convenience functions to something more readable. * Construction of new records is only convenient by using the defaulting system. Maybe that makes sense, maybe it doesn't. A side benefit: Record access functions are reusable between record types (as long as they have the same type). Anyway, thanks again, Wouter! -Ron WouterRecords.hs Description: Binary data ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell's type system
I'm trying to wrap my head around the theoretical aspects of haskell's type system. Is there a discussion of the topic separate from the language itself? Since I come from a rather logic-y background, I have this (far-fetched) hope that there is a translation from haskell's type syntax to first order logic (or an extension there-of). Is this done? Doable? -Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Wouter-style expressions
Here's something that should be an easy extension of Wouter's approach
to extensible datatypes, but I'm failing (possibly since it's 2:20am).
I several classes of expressions I'm trying to represent (thus,
Wouter's approach), and my first operation to implement over them is
printing.
Attached is a simplified version of what I'm doing. Expressions are
composed of conjunctives (and) and atoms. Atoms are composed of a
predicate string and a list of fillers (taken from 'Const' and 'Var').
For example (in a lisp like syntax):
(and (pred c ?var1) (pred ?var1 ?var2))
To do this, I defined a 'Printable' class:
class Functor f = Printable f where
exprDoc :: f t - Doc
I think the 't' here will get me into trouble later.
Combinations of printable types are also printable:
instance (Printable f, Printable g) = Printable (f :+: g) where
exprDoc (Inr x) = exprDoc x
exprDoc (Inl y) = exprDoc y
Constants, variables, and atoms are defined to be printable:
instance Printable Var where
exprDoc (Var name) = text ('?':name)
instance Printable Const where
exprDoc (Const name) = text name
instance Printable f = Printable (Atomic (Expr f)) where
exprDoc (Atomic p tl) = parens $ hsep $
(text p) : (map (\ (In t) - exprDoc t) tl)
But the obvious definition for conjunction doesn't work:
instance Printable And where
exprDoc (And el) = sep (map exprDoc el)
GHC barfs, throwing:
Couldn't match expected type `f t' against inferred type `t1'
`t1' is a rigid type variable bound by
the type signature for `exprDoc' at WouterTest.hs:62:17
Expected type: [f t]
Inferred type: [t1]
In the second argument of `map', namely `el'
In the first argument of `sep', namely `(map exprDoc el)'
I've attached the code. Compile and inspect with:
$ ghci -fglasgow-exts -fallow-overlapping-instances WouterTest.hs
test1 works great (other than needing some redundant typing, any hints?).
test2 needs the definition of 'Printable And' to print, but I haven't
gotten that to work yet. It also needs the redundant typing.
-Ron
However, I tried making more complex expression (conjunction, in this
case), but I can't get the types to align. In particular, if I
uncomment the obvious definition
WouterTest.hs
Description: Binary data
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Mutually recursive types?
Here's the setup: I have a series of problems that use various logical connectives. The problem is that they're not all the same. So instead of creating one giant datatype (or duplicating much code), I'd like to assemble them like toy blocks. I've boiled down an example here: data LogicalConnective a = Not a | And [a] | Or [a] data BasicGoal a = Atomic String [Term] | Empty | Logical (LogicalConnective a) deriving (Show, Eq) data PreferenceGoal1 = Basic1 PreferenceGoal1 | Prefer1 PreferenceGoal1 This works OK, but PreferenceGoal1 is a dead end. I can't combine it with other connectives. So I try: data PreferenceGoal2 a = Basic2 (PreferenceGoal2 a) | Prefer2 (PreferenceGoal2 a) And this works fine, but seems impossible to explicitly type (ie, there is nothing to substitute for 'a' in a type declaration). Or am I wrong? Also, it could be that this is just an ugly way to represent things (it does require a huge number of constructors). Any suggestions? -Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
