January 2009 - Glasgow-haskell-users

RE: Differences in pattern matching syntax?
by Han Joosten 18 Jan '09

18 Jan '09

Hi, I do not use -O to compile, as far as I know. I use eclipsefp and I use the defaults from it. I will upload my modules as a zip file, so you can reproduce the error. It also contains a README.txt file that explains how to reproduce it. Hope that helps. http://www.nabble.com/file/p21439653/src.zip src.zip Simon Peyton-Jones wrote: > > I agree that's odd. Are you using -O? Can you give us a reproducible > test case? > > (The only think I can think is that the line > | Gc{} -> Tm (grspe r) > will build a thunk for (grspe r), and depending on the context I suppose > you might get a lot of those.) > > Thanks > > Simon > > | -----Original Message----- > | From: glasgow-haskell-users-bounces(a)haskell.org > [mailto:glasgow-haskell-users- > | bounces(a)haskell.org] On Behalf Of Han Joosten > | Sent: 12 January 2009 21:54 > | To: glasgow-haskell-users(a)haskell.org > | Subject: Differences in pattern matching syntax? > | > | > | Hi, > | > | I have two alternatives to specify a specific function. They both > compile > | ok, but the first one crashes (Stack space overflow) while the second > one > | runs fine. > | I use GHC 6.10.1 on windowsXP > | > | Alternative 1: > | antecedent :: Rule -> Expression > | antecedent r = case r of > | Ru{} -> if (rrsrt r == AlwaysExpr) then error > ("(Module > | ADLdataDef:) illegal call to antecedent of rule "++show r) > | else > | rrant r > | Sg{} -> antecedent (srsig r) > | Gc{} -> Tm (grspe r) > | Fr{} -> frcmp r > | > | Alternative 2: > | antecedent :: Rule -> Expression > | antecedent r@(Ru AlwaysExpr _ _ _ _ _ _ _ _) = error ("(Module > ADLdef:) > | illegal call to antecedent of rule "++show r) > | antecedent (Ru _ a _ _ _ _ _ _ _) = a > | antecedent (Sg _ rule _ _ _ _ _) = antecedent rule > | antecedent (Gc _ d _ _ _ _ _) = Tm d > | antecedent (Fr _ _ e _) = e > | > | Both alternatives compile, but if i use Alternative 2, then my program > runs > | fine. If I use Alternative 1 instead, I get a stack space overflow. > | > | I would think that both alternatives would have the same semantics. So i > am > | surprised that one runs fine, while the other one crashes. > | > | Could anyone explain what is going on? > | Thanks! > | > | Han Joosten > | > | ---------------------------- > | Might help, here is the data definition: > | > | data Rule = > | -- Ru c antc p cons cpu expla sgn nr pn > | Ru { rrsrt :: RuleType -- ^ One of the following: > | -- | Implication if this is > an > | implication; > | -- | Equivalence if this is > an > | equivalence; > | -- | AlwaysExpr if this is > an > | ALWAYS expression. > | , rrant :: Expression -- ^ Antecedent > | , rrfps :: FilePos -- ^ Position in the ADL file > | , rrcon :: Expression -- ^ Consequent > | , r_cpu :: Expressions -- ^ This is a list of > | subexpressions, which must be computed. > | , rrxpl :: String -- ^ Explanation > | , rrtyp :: (Concept,Concept) -- ^ Sign of this rule > | , runum :: Int -- ^ Rule number > | , r_pat :: String -- ^ Name of pattern in which it > was > | defined. > | } > | -- Sg p rule expla sgn nr pn signal > | | Sg { srfps :: FilePos -- ^ position in the ADL file > | , srsig :: Rule -- ^ the rule to be signalled > | , srxpl :: String -- ^ explanation > | , srtyp :: (Concept,Concept) -- ^ type > | , runum :: Int -- ^ rule number > | , r_pat :: String -- ^ name of pattern in which it > was > | defined. > | , srrel :: Declaration -- ^ the signal relation > | } > | -- Gc p antc cons cpu _ _ _ > | | Gc { grfps :: FilePos -- ^ position in the ADL file > | , grspe :: Morphism -- ^ specific > | , grgen :: Expression -- ^ generic > | , r_cpu :: Expressions -- ^ This is a list of > | subexpressions, which must be computed. > | , grtyp :: (Concept,Concept) -- ^ declaration > | , runum :: Int -- ^ rule number > | , r_pat :: String -- ^ name of pattern in which it > was > | defined. > | } > | -- Fr t d expr pn -- represents an automatic computation, such as * > or +. > | | Fr { fraut :: AutType -- ^ the type of automatic > | computation > | , frdec :: Declaration -- ^ where the result is to be > | stored > | , frcmp :: Expression -- ^ expression to be computed > | , frpat :: String -- ^ name of pattern in which it > was > | defined. > | } > | > | -- > | View this message in context: > http://www.nabble.com/Differences-in-pattern-matching-syntax-- > | tp21416338p21416338.html > | Sent from the Haskell - Glasgow-haskell-users mailing list archive at > Nabble.com. > | > | _______________________________________________ > | Glasgow-haskell-users mailing list > | Glasgow-haskell-users(a)haskell.org > | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users(a)haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > > -- View this message in context: http://www.nabble.com/Differences-in-pattern-matching-syntax--tp21416338p21… Sent from the Haskell - Glasgow-haskell-users mailing list archive at Nabble.com.

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how to load an additional file to ghci
by Peter Hercek 16 Jan '09

16 Jan '09

Is it possible to load one more module to ghci without unloading the modules I have already loaded? The module I would like to load in addtion is not installed and I do not want it installed. It is also independent of any other modules. There is no dependency from the modules already loaded to the one I would like to add. How to achieve something like "load a module in this file in addition to what I have already loaded and do not modify the the context for expression evaluation (:module) ... just make the exported functions in the file available through fully qualified names". It would be handy for some helper stuff I have which is project independent and too often modified to be installed. Peter.

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Re: [Haskell-cafe] HEADS UP: finalizer changes coming in GHC 6.10.2
by Simon Marlow 14 Jan '09

14 Jan '09

Sigbjorn Finne wrote: > Thanks Simon, > > great stuff; I like the introduction of these 'native code finalizers', > they've > been sorely missed at times. > > You don't say, but will there be a dynamic check to catch such re-entries? There is (now) a dynamic check, yes. Cheers, Simon

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HEADS UP: finalizer changes coming in GHC 6.10.2
by Simon Marlow 14 Jan '09

14 Jan '09

By popular demand, GHC 6.10.2 will support finalizers that are actually guaranteed to run, and run promptly. There aren't any API changes: this happens for finalizers created using newForeignPtr as normal. However, there's a catch. Previously it was possible to call back into Haskell from a finalizer (finalizers are C functions), by using foreign import "wrapper" or foreign export. According to the FFI spec, whether this is allowed or not is "system dependent". In GHC 6.10.1 and earlier it was allowed, but in 6.10.2 and later it is not. The reason being that C finalizers are now executed directly by the GC, when the runtime is not in a position to handle callbacks. You can still have fully-fledged Haskell finalizers if you want: we have Foreign.Concurrent.newForeignPtr for that purpose. But those finalizers are not subject to the same promptness guarantees that you get with C finalizers - they run in a separate thread, and are not guaranteed to be run at program exit. We'll make sure this is documented prominently in the 6.10.2 release notes, but I thought a heads-up would be a good idea right now as it turns out that there are existing libraries (e.g. LLVM) that will be affected. Cheers, Simon

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GHCi, version 6.10.1 crashes without message
by Heiko Studt 14 Jan '09

14 Jan '09

Hi (and hello everybody), I read the FAQ, I searched down till Nov 2008, but did not find anything. I hope I didn't miss a FAQ or somewhat. (If so, please apologize!) My (freshly installed) GHCi 6.10.1 runs on Windows XP on Intel Dual Core. I used the .msi of the Webpage some two weeks ago. I got some strange program as example and tried out - and my ghci died quitly without any helping message. Here is the original programm: | f x y z = a + b*c + b + fun c | where a = x * y + z | b = c * fun x | c = a * b | fun x = x * x + 1 For testing out in previous of this posting, the following is the very same and had the same problem: | let f x y z = a + b*c + b + fun c where {a = x * y + z; b = c * fun x; c = a * b; fun x = x * x + 1} The query to die was "f 1 2 3". I tried with verbose ghci: | C:\...\ghc-6.10.1\bin>ghci -v | GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help | Glasgow Haskell Compiler, Version 6.10.1, for Haskell 98, stage 2 booted by GHC | version 6.8.3 | Using package config file: C:\...\GHC-61~1.1\package.conf | hiding package base-3.0.3.0 to avoid conflict with later version base-4.0.0.0 | wired-in package ghc-prim mapped to ghc-prim-0.1.0.0 | wired-in package integer mapped to integer-0.1.0.0 | wired-in package base mapped to base-4.0.0.0 | wired-in package rts mapped to rts-1.0 | wired-in package haskell98 mapped to haskell98-1.0.1.0 | wired-in package syb mapped to syb-0.1.0.0 | wired-in package template-haskell mapped to template-haskell-2.3.0.0 | wired-in package dph-seq mapped to dph-seq-0.3 | wired-in package dph-par mapped to dph-par-0.3 | Hsc static flags: -static | Loading package ghc-prim ... linking ... done. | Loading package integer ... linking ... done. | Loading package base ... linking ... done. | Prelude> let f x y z = a + b*c + b + fun c where {a = x * y + z; b = c * fun x; | c = a * b; fun x = x * x + 1} | *** Parser: | *** Desugar: | *** Simplify: | *** CorePrep: | *** ByteCodeGen: | Prelude> f 1 2 3 | *** Parser: | *** Desugar: | *** Simplify: | *** CorePrep: | *** ByteCodeGen: | | C:\...\ghc-6.10.1\bin> I hope I could help finding some strange bug, killing 99% of your problems with Haskell, life and love, although I am very sure this one is only minor... ;-) MFG (With friendly regards) -- Heiko Studt <studt(a)fmi.uni-passau.de>

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LambdaVM: build fails on Solaris/x86
by Karel Gardas 13 Jan '09

13 Jan '09

Hello Brian and All, I'm curious if anyone here attempted building LambdaVM on non-GNU system. I'm using OpenSolaris/x86 and build fails with: == Recursively making `depend' for ways: '' ... PWD = /export/home/karel/vcs/lambdavm/libraries/Cabal ------------------------------------------------------------------------ case '- --no-print-directory -r' in *-[ik]*) x_on_err=0;; *-r*[ik]*) x_on_err=0;; *) x_on_err=1;; esac; \ if [ -n "" ]; then \ echo "doing the loop :-("; \ for i in ; do \ echo "------------------------------------------------------------------------"; \ echo "== gmake way=$i depend;"; \ echo "PWD = /export/home/karel/vcs/lambdavm/libraries/Cabal"; \ echo "------------------------------------------------------------------------"; \ gmake way=$i --no-print-directory - --no-print-directory -r depend ; \ if [ $? -eq 0 ] ; then true; else exit $x_on_err; fi; \ done \ fi /bin/sh: syntax error at line 4: `;' unexpected gmake[2]: *** [depend] Error 2 Failed making boot in Cabal: 1 gmake[1]: *** [boot] Error 1 gmake[1]: Leaving directory `/export/home/karel/vcs/lambdavm/libraries' gmake: *** [stage1] Error 2 karel@silence:~/vcs/lambdavm$ The only changes which I made to the build systems are following: karel@silence:~/vcs/lambdavm$ darcs w -u { hunk ./darcs-all 1 -#!/bin/sh +#!/usr/bin/bash set -e hunk ./libraries/Makefile 12 # want the Makefile. MFLAGS += -f Makefile -SUBDIRS = base haskell98 template-haskell readline parsec Cabal +#SUBDIRS = base haskell98 template-haskell readline parsec Cabal +SUBDIRS = base haskell98 template-haskell parsec Cabal ifeq "$(GhcLibsWithUnix)" "YES" SUBDIRS += unix hunk ./mk/target.mk 274 ifneq "$(way)" "i" ifeq "$(way)" "j" define BUILD_LIB -@if [ -e $@ ]; then \ +@if [ -f $@ ]; then \ echo "$(JAR) uf $@ ..."; \ for o in $(LIBOBJS:%.$(osuf)=%); do [ $$o.$(osuf) -nt $@ ] && echo $$o*.$(osuf); done | xargs $(JAR) uf $@; \ else \ hunk ./mk/target.mk 1102 # since these are way-independent all docs TAGS clean distclean mostlyclean maintainer-clean install depend :: @echo "------------------------------------------------------------------------" - @echo "== Recursively making \`$@' for ways: $(WAYS) ..." + @echo "== Recursively making \`$@' for ways: '$(WAYS)' ..." @echo "PWD = $(shell pwd)" @echo "------------------------------------------------------------------------" # Don't rely on -e working, instead we check exit return codes from sub-makes. } the reason is: 1) readline lib is not buildable on my solaris. The issue was already solved in 6.8.x branch IIRC somehow (replacing readline with different lib IIRC) 2) if [ -e $@ ], i.e. `-e' is not supported by Solaris' /bin/sh, -f works fine. My main motivation behind attempting to build it, is to give Haskell a try inside Eclipse IDE. i.e. Eclipse supports kind of Model Driven Architecture and I would like to use Haskell for models processing and transformations. Thanks! Karel

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ghci debugger :trace command does not always extend trace history
by Peter Hercek 13 Jan '09

13 Jan '09

Hi, I expected ":trace expr" to always add data to the trace history but it does not do so for CAFs (which are not reduced yet). My point is that the command ":trace z" did not add anything to the trace history and I cannot check why value z is 2, because value of y is not in the trace history. Is this the expected behavior? If it is, how can I make ghci to extend the trace history when "forcing" variables? Peter. Here is the example: status:0 peter@metod [765] ~/tmp % cat a.hs test :: Int -> Int test x = let y = x+1 in let z = y+1 in z status:0 peter@metod [766] ~/tmp % ghci a.hs GHCi, version 6.8.2: http://www.haskell.org/ghc/ :? for help Loading package base ... linking ... done. [1 of 1] Compiling Main ( a.hs, interpreted ) Ok, modules loaded: Main. *Main> :break Main 5 Breakpoint 0 activated at a.hs:5:2 *Main> :trace test 0 Stopped at a.hs:5:2 _result :: Int = _ z :: Int = _ 4 let z = y+1 in 5 z 6 [a.hs:5:2] *Main> :back Logged breakpoint at a.hs:(2,0)-(5,2) _result :: Int 1 test :: Int -> Int 2 test x = 3 let y = x+1 in 4 let z = y+1 in 5 z 6 [-1: a.hs:(2,0)-(5,2)] *Main> :back no more logged breakpoints [-1: a.hs:(2,0)-(5,2)] *Main> :forward Stopped at a.hs:5:2 _result :: Int z :: Int 4 let z = y+1 in 5 z 6 [a.hs:5:2] *Main> :trace z 2 [a.hs:5:2] *Main> :back Logged breakpoint at a.hs:(2,0)-(5,2) _result :: Int 1 test :: Int -> Int 2 test x = 3 let y = x+1 in 4 let z = y+1 in 5 z 6 [-1: a.hs:(2,0)-(5,2)] *Main> y <interactive>:1:0: Not in scope: `y' [-1: a.hs:(2,0)-(5,2)] *Main> :back no more logged breakpoints [-1: a.hs:(2,0)-(5,2)] *Main> :forward Stopped at a.hs:5:2 _result :: Int z :: Int 4 let z = y+1 in 5 z 6 [a.hs:5:2] *Main> z 2 [a.hs:5:2] *Main> y <interactive>:1:0: Not in scope: `y' [a.hs:5:2] *Main> :quit Leaving GHCi. status:0 peter@metod [767] ~/tmp %

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RE: [Haskell] type family vs. polymorphism
by Simon Peyton-Jones 13 Jan '09

13 Jan '09

[Redirecting to GHC users] Andres, Nice example. It's another instance of a problem that keeps coming up with type families. Details here: http://hackage.haskell.org/trac/ghc/ticket/1897#comment:10 The rest of the ticket gives other examples. It's not clear what the Right Thing to do is. Simon | -----Original Message----- | From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of Andres | Loeh | Sent: 12 January 2009 21:44 | To: haskell(a)haskell.org | Subject: [Haskell] type family vs. polymorphism | | Hi. | | Here's a strange interaction of type families and higher-rank | polymorphism (tested with both ghc-6.8.3 and ghc-6.10.1): | | {-# LANGUAGE TypeFamilies, EmptyDataDecls, RankNTypes #-} | | data X (a :: *) | type family Y (a :: *) | | -- This works (datatype). | i1 :: (forall a. X a) -> X Bool | i1 x = x | | -- This works too (type family and extra arg). | i2 :: (forall a. a -> Y a) -> Y Bool | i2 x = x True | | -- This doesn't work (type family). | -- i3 :: (forall a. Y a) -> Y Bool | -- i3 x = x | | I would expect i3 to be ok as well. Note that this is a | simplified example and not really useful in its simplified | form. | | Cheers, | Andres | | -- | | Andres Loeh, Universiteit Utrecht | | mailto:andres@cs.uu.nl mailto:mail@andres-loeh.de | http://www.andres-loeh.de | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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Differences in pattern matching syntax?
by Han Joosten 13 Jan '09

13 Jan '09

Hi, I have two alternatives to specify a specific function. They both compile ok, but the first one crashes (Stack space overflow) while the second one runs fine. I use GHC 6.10.1 on windowsXP Alternative 1: antecedent :: Rule -> Expression antecedent r = case r of Ru{} -> if (rrsrt r == AlwaysExpr) then error ("(Module ADLdataDef:) illegal call to antecedent of rule "++show r) else rrant r Sg{} -> antecedent (srsig r) Gc{} -> Tm (grspe r) Fr{} -> frcmp r Alternative 2: antecedent :: Rule -> Expression antecedent r@(Ru AlwaysExpr _ _ _ _ _ _ _ _) = error ("(Module ADLdef:) illegal call to antecedent of rule "++show r) antecedent (Ru _ a _ _ _ _ _ _ _) = a antecedent (Sg _ rule _ _ _ _ _) = antecedent rule antecedent (Gc _ d _ _ _ _ _) = Tm d antecedent (Fr _ _ e _) = e Both alternatives compile, but if i use Alternative 2, then my program runs fine. If I use Alternative 1 instead, I get a stack space overflow. I would think that both alternatives would have the same semantics. So i am surprised that one runs fine, while the other one crashes. Could anyone explain what is going on? Thanks! Han Joosten ---------------------------- Might help, here is the data definition: data Rule = -- Ru c antc p cons cpu expla sgn nr pn Ru { rrsrt :: RuleType -- ^ One of the following: -- | Implication if this is an implication; -- | Equivalence if this is an equivalence; -- | AlwaysExpr if this is an ALWAYS expression. , rrant :: Expression -- ^ Antecedent , rrfps :: FilePos -- ^ Position in the ADL file , rrcon :: Expression -- ^ Consequent , r_cpu :: Expressions -- ^ This is a list of subexpressions, which must be computed. , rrxpl :: String -- ^ Explanation , rrtyp :: (Concept,Concept) -- ^ Sign of this rule , runum :: Int -- ^ Rule number , r_pat :: String -- ^ Name of pattern in which it was defined. } -- Sg p rule expla sgn nr pn signal | Sg { srfps :: FilePos -- ^ position in the ADL file , srsig :: Rule -- ^ the rule to be signalled , srxpl :: String -- ^ explanation , srtyp :: (Concept,Concept) -- ^ type , runum :: Int -- ^ rule number , r_pat :: String -- ^ name of pattern in which it was defined. , srrel :: Declaration -- ^ the signal relation } -- Gc p antc cons cpu _ _ _ | Gc { grfps :: FilePos -- ^ position in the ADL file , grspe :: Morphism -- ^ specific , grgen :: Expression -- ^ generic , r_cpu :: Expressions -- ^ This is a list of subexpressions, which must be computed. , grtyp :: (Concept,Concept) -- ^ declaration , runum :: Int -- ^ rule number , r_pat :: String -- ^ name of pattern in which it was defined. } -- Fr t d expr pn -- represents an automatic computation, such as * or +. | Fr { fraut :: AutType -- ^ the type of automatic computation , frdec :: Declaration -- ^ where the result is to be stored , frcmp :: Expression -- ^ expression to be computed , frpat :: String -- ^ name of pattern in which it was defined. } -- View this message in context: http://www.nabble.com/Differences-in-pattern-matching-syntax--tp21416338p21… Sent from the Haskell - Glasgow-haskell-users mailing list archive at Nabble.com.

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Solaris/x86 bot failing on stage2 haddock installation.
by Karel Gardas 11 Jan '09

11 Jan '09

Hello, so it seems I'm still not lucky get head compiling well on solaris/x86 bot. This time compilation fails on stage2 at the haddock installation with following message: Installing library in /buildbot/ghc/kgardas/build/utils/haddock/install-inplace/lib/haddock-2.4.2 Installing executable(s) in /buildbot/ghc/kgardas/build/utils/haddock/install-inplace/bin Registering haddock-2.4.2... ghc-pkg: /buildbot/ghc/kgardas/build/ghc/inplace-datadir/package.conf: openFile: does not exist (No such file or directory) make[2]: *** [install-inplace] Error 1 make[2]: Leaving directory `/buildbot/ghc/kgardas/build/utils/haddock' make[1]: *** [with-stage-2] Error 2 make[1]: Leaving directory `/buildbot/ghc/kgardas/build/utils' make: *** [stage2] Error 2 see http://darcs.haskell.org/buildbot/all/builders/kgardas%20head/builds/98/ste… for more information. Do you have any idea what's going wrong this time? Is it a problem of my bot (shall I install anything else?) or is it GHC's issue? Thanks! Karel

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