January 2011 - Glasgow-haskell-users

partially applied type synonyms
by Arie Peterson 05 Mar '12

05 Mar '12

Dear list, Is there a good reason that partially applied type synonyms cannot be made instances of classes? - A simple example would be making the identity type 'Id' ("type Id x = x") instance of 'Monad'. This would eliminate the need for some silly occurrences of 'runIdentity', and perhaps narrow the gap between monads and monad transformers. - The reason I complain about this now is a more involved example, where introducing a newtype to work around the restriction is not an option. Well, not as far as I can see now, anyway. Partially applied type synonyms are, in a sense, the anonymous functions at the type level, and one might argue that they deserve the same 'first-class member status' as the lambda at the value level. Kind regards, Arie Peterson

3 2

MonoLocalBinds and hoopl
by Edward Z. Yang 19 Jun '11

19 Jun '11

Hello all, Here's an experience report for porting hoopl to manage MonoLocalBinds. The Compiler.Hoop.XUtil module has a rather interesting (but probably common) style of code writing, along the lines of this: fbnf3 (ff, fm, fl) block = unFF3 $ scottFoldBlock (ScottBlock f m l cat) block where f n = FF3 $ ff n m n = FF3 $ fm n l n = FF3 $ fl n FF3 f `cat` FF3 f' = FF3 $ f' . f f, m, l and cat are polymorphic functions that are only used once in the main expression, and are floated outside to improve readability. However, when MonoLocalBinds is turned on, these all become monomorphic and the definitions fail. In contrast, this (uglier) version typechecks: fbnf3 (ff, fm, fl) block = unFF3 $ scottFoldBlock (ScottBlock (FF3 . ff) (FF3 . fm) (FF3 . fl) (\(FF3 f) (FF3 f') -> FF3 $ f' . f)) block One suggestion that I had was that we should generalize local bindings that are only used once, but Marlow pointed out that this would make the typechecker more complex and I probably would agree. As a userspace developer, I have two options: 1. Bite the bullet and put in the polymorphic type signatures (which can be quite hefty) 2. Inline the definitions 3. Move the polymorphic functions into the global namespace (3) and (2) are not so nice because it breaks the nice symmetry between these definitions, which always define f, m, l for the many, many definitions in Hoopl of this style. Cheers, Edward

6 8

trac ticket spam
by Claus Reinke 14 Mar '11

14 Mar '11

Is there any way to have a "moderate first comment by new submitter" policy for trac, to avoid the kind of ticket spam we have at the moment? They seem to have started commenting on existing tickets now (#4510), which could turn into a real mess really quickly, if the currently known spam accounts aren't blocked soon, btw. Claus

6 10

ANNOUNCE: GHC 7.0.2 Release Candidate 1
by Ian Lynagh 26 Feb '11

26 Feb '11

We are pleased to announce the first release candidate for GHC 7.0.2: http://www.haskell.org/ghc/dist/7.0.2-rc1/ This includes the source tarball, installers for OS X and Windows, and bindists for amd64/Linux, i386/Linux, amd64/FreeBSD and i386/FreeBSD. Please test as much as possible; bugs are much cheaper if we find them before the release! Thanks Ian, on behalf of the GHC team

10 17

Question about Haskell AST
by Jane Ren 22 Feb '11

22 Feb '11

Hi, I need to be able to take a piece of Haskell source code and get an simplified, typed, intermediate representation of the AST, which means I need to use compiler/coreSyn/CoreSyn.lhs So I'm first trying to get the desguaredModule of the source code with ... modSum <- getModSummary $ mkModuleName "..." p <- parseModule modSum t <- typecheckModule p d <- desugarModule t Now I'm really stuck on figuring out how to connect the variable d of type desugaredModule to compiler/coreSyn/CoreSyn.lhs to get Expr patterns like App, Let, Case, etc. Also, is it correct to get the deguaredModule first? At least CoreSyn.lhs seems to suggest this. Any suggestions would be greatly apprecia

6 10

RFC: migrating to git
by Simon Marlow 09 Feb '11

09 Feb '11

It's time to consider again whether we should migrate GHC development from darcs to (probably) git. From our perspective at GHC HQ, the biggest problem that we would hope to solve by switching is that darcs makes branching and merging very difficult for us. We have a few branches of HEAD that are very painful to keep merged with HEAD, and we would almost certainly have more branches if the overhead were lower. In some sense the overhead is self-inflicted because we have the no-conflict policy in the mainline repository, but that is to avoid problems with darcs' merging algorithms (both performance and correctness). We are still using darcs v1 patches rather than v2, but there are known problems with v2 which are preventing us from upgrading. The darcs team have been making great strides with performance, but conflict handling remains a serious problem. The darcs roadmap doesn't show this being fixed in the near future http://wiki.darcs.net/Roadmap Rebase support is coming, and it does work, though the workflow is a bit laborious. Besides the branching/merging/conflict issue, switching to git would give us plenty of side benefits, notably via access to a wealth of tool support. Making contribution easy is important to us too, and there are a lot of people using git. The cost of switching is quite high, which is one reason we decided to stay with darcs last time. We have multiple repos that need to be converted, and for some of them, where the repo is being shared with other projects, we may have to mirror rather than convert in place. We're prepared to put in the effort if the gains would be worthwhile though (offers of help are more than welcome!). We're intrested in opinions from both active and potential GHC developers/contributors. Let us know what you think - would this make life harder or easier for you? Would it make you less likely or more likely to contribute? Cheers, Simon

34 81

4221 on new codegen
by Edward Z. Yang 04 Feb '11

04 Feb '11

Test 4221 (under the ffi folder) segfaults with the new codegen turned on. Before: 0xb7a68c78: 0x822fadc <stg_ap_v_info> 0xb7a68c74: 0xb7ab8f94 0xb7a68c70: 0xb7ab8fa4 0xb7a68c6c: 0x8134dc0 <stT_info> 0xb7a68c68: 0xb7ab8f94 0xb7a68c64: 0x822f9f4 <stg_marked_upd_frame_info> 0xb7a68c60: 0xb7ab8f48 0xb7a68c5c: 0xb7ab8f88 0xb7a68c58: 0x4063a000 # this is the counted float; this 0xb7a68c54: 0x0 # val is 157.0 0xb7a68c50: 0x804bbc0 <c1jG_info> After: 0xb7a68c78: 0x822fadc <stg_ap_v_info> 0xb7a68c74: 0xb7ab8f94 0xb7a68c70: 0xb7ab8fa4 0xb7a68c6c: 0x8134dc0 <stT_info> 0xb7a68c68: 0xb7ab8f94 0xb7a68c64: 0x822f9f4 <stg_marked_upd_frame_info> 0xb7a68c60: 0xb7ab8f48 0xb7a68c5c: 0xb7ab8f88 0xb7a68c58: 0x4063a000 0xb7a68c54: 0x0 It then jumps c1jL_entry to which jumps to stg_gc_d1_info which segfaults on return because 0xb7a68c54 is not a valid address. The offending assembly: (gdb) disas Dump of assembler code for function c1jG_info: 0x0804bbc0 <+0>: fldl 0x4(%ebp) 0x0804bbc3 <+3>: fstp %st(1) 0x0804bbc5 <+5>: fstl 0x4(%ebp) 0x0804bbc8 <+8>: add $0x4,%ebp => 0x0804bbcb <+11>: ffree %st(0) 0x0804bbcd <+13>: ffree %st(1) 0x0804bbcf <+15>: ffree %st(2) 0x0804bbd1 <+17>: ffree %st(3) 0x0804bbd3 <+19>: ffree %st(4) 0x0804bbd5 <+21>: ffree %st(5) 0x0804bbd7 <+23>: jmp 0x804bbdc <c1jL_entry> 0x0804bbd9 <+25>: lea 0x0(%esi),%esi Optimized C--: block_c1jG_entry() { [const 484;, const 32;] } c1jG: // emitReturn: Sequel: Assign _s1ev::F64 = F64[Sp + 4]; ; F64[Sp + 4] = _s1ev::F64; Sp = Sp + 4; jump block_c1jL_entry (); } Regardless of whether or not it's right, this is pretty dumb code, so we should fix the codegen not to do that. I'm not sure what this code is /supposed/ to be doing, or what generated it. This bit might be correct and the FFI call leading up to it may be wrong. I have a prodigous amout of difficulty trying to figure out if what's on the stack is right or not: maybe we could have a chat about this. Cheers, Edward Some possible useful raw data: Raw C--: block_c1jh_entry() { [const 484;, const 32;] } c1jh: // emitReturn: Sequel: Assign _s1ev::F64 = F64[Sp + 4]; _s1ev::F64 = _s1ev::F64; F64[Sp + 4] = _s1ev::F64; Sp = Sp + 4; jump block_c1jm_entry (); } after manifest SP {offset c1j0: _s1el::I32 = I32[Sp + 4]; // CmmAssign I32[Sp - 4] = _s1el::I32; // CmmStore _s1ei::I32 = I32[Sp + 0]; // CmmAssign if (Sp - 12 < SpLim) goto u1Am; else goto u1Ao; // CmmCondBranch u1Am: Sp = Sp + 12; // CmmAssign goto c1j7; // CmmBranch c1j7: // outOfLine here R1 = call_fn_blob_rk2_closure; // CmmAssign Sp = Sp - 12; // CmmAssign call (stg_gc_fun)(...) returns to Nothing (12) (0) with update frame 12; // CmmCall u1Ao: Sp = Sp + 12; // CmmAssign goto c1j3; // CmmBranch c1j3: // outOfLine should follow: if (_s1ei::I32 & 3 != 0) goto c1j9; else goto c1j8; // CmmCondBranch c1j9: // emitReturn: Sequel: Assign _s1fO::I32 = _s1ei::I32; // CmmAssign I32[Sp - 20] = _s1fO::I32; // CmmStore goto u1Ai; // CmmBranch u1Ai: Sp = Sp - 20; // CmmAssign goto c1jc; // CmmBranch c1j8: // emitCall: Sequel: Assign R1 = _s1ei::I32; // CmmAssign I32[Sp - 20] = c1iw; // CmmStore Sp = Sp - 20; // CmmAssign call (I32[_s1ei::I32])(...) returns to Just c1iw (4) (4) with update frame 4; // CmmCall c1iw: _s1fO::I32 = R1; // CmmAssign I32[Sp + 0] = _s1fO::I32; // CmmStore Sp = Sp + 4; // CmmAssign goto u1Af; // CmmBranch u1Af: Sp = Sp - 4; // CmmAssign goto c1jc; // CmmBranch c1jc: // outOfLine should follow: _s1fO::I32 = I32[Sp + 0]; // CmmAssign _s1ep::I32 = I32[_s1fO::I32 + 3]; // CmmAssign I32[Sp + 0] = _s1ep::I32; // CmmStore _s1el::I32 = I32[Sp + 4]; // CmmAssign if (_s1el::I32 & 3 != 0) goto c1jf; else goto c1je; // CmmCondBranch c1jf: // emitReturn: Sequel: Assign _s1el::I32 = I32[Sp + 4]; // CmmAssign _s1fP::I32 = _s1el::I32; // CmmAssign I32[Sp - 4] = _s1fP::I32; // CmmStore goto u1Aj; // CmmBranch u1Aj: Sp = Sp - 4; // CmmAssign goto c1jj; // CmmBranch c1je: // emitCall: Sequel: Assign _s1el::I32 = I32[Sp + 4]; // CmmAssign R1 = _s1el::I32; // CmmAssign I32[Sp - 4] = c1iG; // CmmStore _s1el::I32 = I32[Sp + 4]; // CmmAssign Sp = Sp - 4; // CmmAssign call (I32[_s1el::I32])(...) returns to Just c1iG (4) (4) with update frame 4; // CmmCall c1iG: _s1fP::I32 = R1; // CmmAssign I32[Sp + 0] = _s1fP::I32; // CmmStore Sp = Sp + 4; // CmmAssign goto u1Ag; // CmmBranch u1Ag: Sp = Sp - 4; // CmmAssign goto c1jj; // CmmBranch c1jj: // outOfLine should follow: _s1fP::I32 = I32[Sp + 0]; // CmmAssign _s1eq::F64 = F64[_s1fP::I32 + 3]; // CmmAssign I32[Sp + 0] = c1jh; // CmmStore _s1ep::I32 = I32[Sp + 4]; // CmmAssign foreign call "ccall" arg hints: [PtrHint,] result hints: [] call_fn_blob(...) returns to c1jh args: ([_s1ep::I32, _s1eq::F64]) ress: ([_s1ev::F64]) with update frame 4; // CmmForeignCall c1jh: // emitReturn: Sequel: Assign _s1ev::F64 = F64[Sp + 4]; // CmmAssign _s1ev::F64 = _s1ev::F64; // CmmAssign F64[Sp + 4] = _s1ev::F64; // CmmStore Sp = Sp + 4; // CmmAssign goto u1Ak; // CmmBranch u1Ak: goto c1jm; // CmmBranch c1jm: Hp = Hp + 12; // CmmAssign if (Hp > HpLim) goto c1jn; else goto c1jl; // CmmCondBranch c1jn: HpAlloc = 12; // CmmAssign // outOfLine here _s1ev::F64 = F64[Sp + 0]; // CmmAssign F64[Sp - 4] = _s1ev::F64; // CmmStore I32[Sp + 4] = c1iT; // CmmStore Sp = Sp - 4; // CmmAssign call stg_gc_d1(...) returns to Just c1iT (12) (12) with update frame 4; // CmmCall c1iT: _s1ev::F64 = F64[Sp + 0]; // CmmAssign F64[Sp + 4] = _s1ev::F64; // CmmStore Sp = Sp + 12; // CmmAssign goto u1Ah; // CmmBranch u1Ah: Sp = Sp - 8; // CmmAssign goto c1jm; // CmmBranch c1jl: // outOfLine should follow: // allocDynClosure I32[Hp - 8] = GHC.Types.D#_con_info; // CmmStore _s1ev::F64 = F64[Sp + 0]; // CmmAssign F64[Hp - 4] = _s1ev::F64; // CmmStore _c1iZ::I32 = Hp - 8; // CmmAssign // emitReturn: Sequel: Return R1 = _c1iZ::I32 + 1; // CmmAssign Sp = Sp + 16; // CmmAssign call (I32[Sp + 0])(...) returns to Nothing (4) (0) with update frame 4; // CmmCall } post dead assignment elimination {offset c1j0: _s1el::I32 = I32[(old + 8)]; // CmmAssign I32[(slot<_s1el::I32> + 4)] = _s1el::I32; // CmmStore _s1ei::I32 = I32[(old + 12)]; // CmmAssign if (Sp - <highSp> < SpLim) goto c1j7; else goto c1j3; // CmmCondBranch c1j7: // outOfLine here R1 = call_fn_blob_rk2_closure; // CmmAssign call (stg_gc_fun)(...) returns to Nothing (12) (0) with update frame 12; // CmmCall c1j3: // outOfLine should follow: if (_s1ei::I32 & 3 != 0) goto c1j9; else goto c1j8; // CmmCondBranch c1j9: // emitReturn: Sequel: Assign _s1fO::I32 = _s1ei::I32; // CmmAssign I32[(slot<_s1fO::I32> + 4)] = _s1fO::I32; // CmmStore goto u1Ai; // CmmBranch u1Ai: goto c1jc; // CmmBranch c1j8: // emitCall: Sequel: Assign R1 = _s1ei::I32; // CmmAssign I32[(young<c1iw> + 4)] = c1iw; // CmmStore call (I32[_s1ei::I32])(...) returns to Just c1iw (4) (4) with update frame 4; // CmmCall c1iw: _s1fO::I32 = R1; // CmmAssign I32[(slot<_s1fO::I32> + 4)] = _s1fO::I32; // CmmStore goto u1Af; // CmmBranch u1Af: goto c1jc; // CmmBranch c1jc: // outOfLine should follow: _s1fO::I32 = I32[(slot<_s1fO::I32> + 4)]; // CmmAssign _s1ep::I32 = I32[_s1fO::I32 + 3]; // CmmAssign I32[(slot<_s1ep::I32> + 4)] = _s1ep::I32; // CmmStore _s1el::I32 = I32[(slot<_s1el::I32> + 4)]; // CmmAssign if (_s1el::I32 & 3 != 0) goto c1jf; else goto c1je; // CmmCondBranch c1jf: // emitReturn: Sequel: Assign _s1el::I32 = I32[(slot<_s1el::I32> + 4)]; // CmmAssign _s1fP::I32 = _s1el::I32; // CmmAssign I32[(slot<_s1fP::I32> + 4)] = _s1fP::I32; // CmmStore goto u1Aj; // CmmBranch u1Aj: goto c1jj; // CmmBranch c1je: // emitCall: Sequel: Assign _s1el::I32 = I32[(slot<_s1el::I32> + 4)]; // CmmAssign R1 = _s1el::I32; // CmmAssign I32[(young<c1iG> + 4)] = c1iG; // CmmStore _s1el::I32 = I32[(slot<_s1el::I32> + 4)]; // CmmAssign call (I32[_s1el::I32])(...) returns to Just c1iG (4) (4) with update frame 4; // CmmCall c1iG: _s1fP::I32 = R1; // CmmAssign I32[(slot<_s1fP::I32> + 4)] = _s1fP::I32; // CmmStore goto u1Ag; // CmmBranch u1Ag: goto c1jj; // CmmBranch c1jj: // outOfLine should follow: _s1fP::I32 = I32[(slot<_s1fP::I32> + 4)]; // CmmAssign _s1eq::F64 = F64[_s1fP::I32 + 3]; // CmmAssign I32[(young<c1jh> + 4)] = c1jh; // CmmStore _s1ep::I32 = I32[(slot<_s1ep::I32> + 4)]; // CmmAssign foreign call "ccall" arg hints: [PtrHint,] result hints: [] call_fn_blob(...) returns to c1jh args: ([_s1ep::I32, _s1eq::F64]) ress: ([_s1ev::F64]) with update frame 4; // CmmForeignCall c1jh: // emitReturn: Sequel: Assign _s1ev::F64 = F64[(slot<_s1ev::F64> + 8)]; // CmmAssign _s1ev::F64 = _s1ev::F64; // CmmAssign F64[(slot<_s1ev::F64> + 8)] = _s1ev::F64; // CmmStore goto u1Ak; // CmmBranch u1Ak: goto c1jm; // CmmBranch c1jm: Hp = Hp + 12; // CmmAssign if (Hp > HpLim) goto c1jn; else goto c1jl; // CmmCondBranch c1jn: HpAlloc = 12; // CmmAssign // outOfLine here _s1ev::F64 = F64[(slot<_s1ev::F64> + 8)]; // CmmAssign F64[(young<c1iT> + 12)] = _s1ev::F64; // CmmStore I32[(young<c1iT> + 4)] = c1iT; // CmmStore call stg_gc_d1(...) returns to Just c1iT (12) (12) with update frame 4; // CmmCall c1iT: _s1ev::F64 = F64[(young<c1iT> + 12)]; // CmmAssign F64[(slot<_s1ev::F64> + 8)] = _s1ev::F64; // CmmStore goto u1Ah; // CmmBranch u1Ah: goto c1jm; // CmmBranch c1jl: // outOfLine should follow: // allocDynClosure I32[Hp - 8] = GHC.Types.D#_con_info; // CmmStore _s1ev::F64 = F64[(slot<_s1ev::F64> + 8)]; // CmmAssign F64[Hp - 4] = _s1ev::F64; // CmmStore _c1iZ::I32 = Hp - 8; // CmmAssign // emitReturn: Sequel: Return R1 = _c1iZ::I32 + 1; // CmmAssign call (I32[(old + 4)])(...) returns to Nothing (4) (0) with update frame 4; // CmmCall }

4 13

Re: Kernel panic when building HEAD on OS X 10.6.4
by Johan Tibell 03 Feb '11

03 Feb '11

On Mon, Jan 31, 2011 at 4:33 AM, Manuel M T Chakravarty <mchakravarty(a)mac.com> wrote: > Are you building inside a Parallels VM? If so, it is probably a Parallels bug (which also explain why compiling GHC can lead to a kernel panic). > > If the GHC build is not in a Parallels VM, I would suggest to shut down Parallels and try again. If the problem does not occur without Parallels running, it's probably a bug in some of Parallel's virtualisation infrastructure. I'm not running in a VM. I shut down parallels and also unloaded its kernel extensions by running: sudo launchctl stop com.parallels.vm.prl_naptd sudo launchctl stop com.parallels.desktop.launchdaemon sudo kextunload -b com.parallels.kext.prl_hypervisor sudo kextunload -b com.parallels.kext.prl_hid_hook sudo kextunload -b com.parallels.kext.prl_usb_connect sudo kextunload -b com.parallels.kext.prl_netbridge sudo kextunload -b com.parallels.kext.prl_vnic It still panics. Here's the crash log without the parallels extensions: ===== Interval Since Last Panic Report: 109637 sec Panics Since Last Report: 3 Anonymous UUID: 32C0D5F6-F2B2-4DB3-A784-F4B33799DE63 Mon Jan 31 09:42:12 2011 panic(cpu 1 caller 0x2a8ab2): Kernel trap at 0x0046d801, type 14=page fault, registers: CR0: 0x8001003b, CR2: 0x00000018, CR3: 0x00100000, CR4: 0x00000660 EAX: 0x08014cb4, EBX: 0x08014cb4, ECX: 0x09af4304, EDX: 0x00000000 CR2: 0x00000018, EBP: 0x56b9be68, ESI: 0x09af4304, EDI: 0x0728c7e0 EFL: 0x00010297, EIP: 0x0046d801, CS: 0x00000008, DS: 0x072d0010 Error code: 0x00000000 Backtrace (CPU 1), Frame : Return Address (4 potential args on stack) 0x56b9bc88 : 0x21b455 (0x5cf328 0x56b9bcbc 0x2238b1 0x0) 0x56b9bcd8 : 0x2a8ab2 (0x591664 0x46d801 0xe 0x59182e) 0x56b9bdb8 : 0x29e9a8 (0x56b9bdd0 0x90853d4 0x56b9be68 0x46d801) 0x56b9bdc8 : 0x46d801 (0xe 0x48 0x56b90010 0x72d0010) 0x56b9be68 : 0x49cf8c (0x8014cb4 0x9af4304 0x56b9bebc 0x0) 0x56b9be88 : 0x46ec97 (0x9af4304 0x0 0x1da230 0x18) 0x56b9bed8 : 0x4933de (0x72da9e0 0x12baec80 0x0 0x0) 0x56b9bf78 : 0x4ed78d (0x9a157e0 0x87ae7c0 0x87ae804 0x0) 0x56b9bfc8 : 0x29eef8 (0x8957060 0x0 0x10 0x8954fc0) BSD process name corresponding to current thread: ghc-stage2 Mac OS version: 10F569 Kernel version: Darwin Kernel Version 10.4.0: Fri Apr 23 18:28:53 PDT 2010; root:xnu-1504.7.4~1/RELEASE_I386 System model name: MacBookPro7,1 (Mac-F222BEC8) System uptime in nanoseconds: 429843412257 unloaded kexts: com.parallels.kext.prl_usb_connect 6.0 11828.615184 (addr 0x5807e000, size 0x24576) - last unloaded 317902627354 loaded kexts: com.pgp.kext.PGPnke 1.1.0 - last loaded 64160566115 com.sophos.kext.sav 7.2.0 com.pgp.iokit.PGPwdeDriver 1.2.0d1 com.apple.driver.AppleHWSensor 1.9.3d0 com.apple.filesystems.autofs 2.1.0 com.apple.driver.AGPM 100.12.12 com.apple.driver.AudioAUUC 1.4 com.apple.Dont_Steal_Mac_OS_X 7.0.0 com.apple.iokit.CHUDUtils 364 com.apple.driver.AppleMikeyHIDDriver 1.2.0 com.apple.iokit.CHUDProf 364 com.apple.driver.AppleMikeyDriver 1.8.7f1 com.apple.driver.AppleIntelPenrynProfile 17.1 com.apple.driver.AppleHDA 1.8.7f1 com.apple.driver.AppleUpstreamUserClient 3.3.2 com.apple.driver.AudioIPCDriver 1.1.2 com.apple.driver.AppleLPC 1.4.12 com.apple.driver.AppleBacklight 170.0.24 com.apple.driver.SMCMotionSensor 3.0.0d4 com.apple.iokit.AppleBCM5701Ethernet 2.3.9b3 com.apple.driver.ACPI_SMC_PlatformPlugin 4.1.2b1 com.apple.GeForce 6.1.8 com.apple.driver.AirPortBrcm43224 425.16.2 com.apple.kext.AppleSMCLMU 1.5.0d3 com.apple.driver.AppleUSBTCButtons 1.8.1b1 com.apple.driver.AppleIRController 303.8 com.apple.driver.AppleUSBTCKeyboard 1.8.1b1 com.apple.driver.AppleUSBCardReader 2.5.4 com.apple.iokit.SCSITaskUserClient 2.6.5 com.apple.iokit.IOAHCIBlockStorage 1.6.2 com.apple.driver.AppleUSBHub 4.0.0 com.apple.driver.AppleUSBEHCI 4.0.2 com.apple.BootCache 31 com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0d1 com.apple.driver.AppleUSBOHCI 3.9.6 com.apple.driver.AppleFWOHCI 4.7.1 com.apple.driver.AppleAHCIPort 2.1.2 com.apple.driver.AppleEFINVRAM 1.3.0 com.apple.driver.AppleRTC 1.3.1 com.apple.driver.AppleHPET 1.5 com.apple.driver.AppleSmartBatteryManager 160.0.0 com.apple.driver.AppleACPIButtons 1.3.2 com.apple.driver.AppleSMBIOS 1.6 com.apple.driver.AppleACPIEC 1.3.2 com.apple.driver.AppleAPIC 1.4 com.apple.driver.AppleIntelCPUPowerManagementClient 105.10.0 com.apple.security.sandbox 0 com.apple.security.quarantine 0 com.apple.nke.applicationfirewall 2.1.11 com.apple.driver.AppleIntelCPUPowerManagement 105.10.0 com.apple.driver.AppleProfileReadCounterAction 17 com.apple.driver.AppleProfileTimestampAction 10 com.apple.driver.AppleProfileThreadInfoAction 14 com.apple.driver.AppleProfileRegisterStateAction 10 com.apple.driver.AppleProfileKEventAction 10 com.apple.driver.AppleProfileCallstackAction 20 com.apple.iokit.IOSurface 74.0 com.apple.iokit.IOBluetoothSerialManager 2.3.7f1 com.apple.iokit.IOSerialFamily 10.0.3 com.apple.iokit.CHUDKernLib 365 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com.apple.iokit.IOSCSIBlockCommandsDevice 2.6.5 com.apple.driver.AppleUSBMergeNub 4.0.0 com.apple.driver.AppleUSBComposite 3.9.0 com.apple.iokit.IOSCSIMultimediaCommandsDevice 2.6.5 com.apple.iokit.IOBDStorageFamily 1.6 com.apple.iokit.IODVDStorageFamily 1.6 com.apple.iokit.IOCDStorageFamily 1.6 com.apple.iokit.IOAHCISerialATAPI 1.2.4 com.apple.iokit.IOSCSIArchitectureModelFamily 2.6.5 com.apple.iokit.IOUSBUserClient 4.0.0 com.apple.iokit.IOUSBFamily 4.0.2 com.apple.iokit.IOFireWireFamily 4.2.6 com.apple.iokit.IOAHCIFamily 2.0.4 com.apple.driver.AppleEFIRuntime 1.3.0 com.apple.iokit.IOHIDFamily 1.6.5 com.apple.iokit.IOSMBusFamily 1.1 com.apple.security.TMSafetyNet 6 com.apple.kext.AppleMatch 1.0.0d1 com.apple.driver.DiskImages 283 com.apple.iokit.IOStorageFamily 1.6.1 com.apple.driver.AppleACPIPlatform 1.3.2 com.apple.iokit.IOPCIFamily 2.6 com.apple.iokit.IOACPIFamily 1.3.0 Model: MacBookPro7,1, BootROM MBP71.0039.B05, 2 processors, Intel Core 2 Duo, 2.66 GHz, 4 GB, SMC 1.62f6 Graphics: NVIDIA GeForce 320M, NVIDIA GeForce 320M, PCI, 256 MB Memory Module: global_name AirPort: spairport_wireless_card_type_airport_extreme (0x14E4, 0x8D), Broadcom BCM43xx 1.0 (5.10.131.16.1) Bluetooth: Version 2.3.7f1, 2 service, 12 devices, 1 incoming serial ports Network Service: AirPort, AirPort, en1 Serial ATA Device: APPLE SSD TS128B, 113 GB Serial ATA Device: MATSHITADVD-R UJ-898 USB Device: Internal Memory Card Reader, 0x05ac (Apple Inc.), 0x8403, 0x26100000 USB Device: Built-in iSight, 0x05ac (Apple Inc.), 0x8507, 0x24600000 USB Device: BRCM2046 Hub, 0x0a5c (Broadcom Corp.), 0x4500, 0x06600000 USB Device: Bluetooth USB Host Controller, 0x05ac (Apple Inc.), 0x8213, 0x06610000 USB Device: IR Receiver, 0x05ac (Apple Inc.), 0x8242, 0x06500000 USB Device: Apple Internal Keyboard / Trackpad, 0x05ac (Apple Inc.), 0x0236, 0x06300000 ===== > If it also happens without Parallels running, the suggestion to check your RAM sounds like good advice. The (OS X modified version of) memtest86 reports no problems. Johan

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Bug in undecidable instances?
by Roman Cheplyaka 01 Feb '11

01 Feb '11

The following looks like a bug in (undecidable) instances resolution. {-# LANGUAGE MultiParamTypeClasses,FlexibleInstances,UndecidableInstances, OverlappingInstances,IncoherentInstances #-} class C a b instance C a (a,b) class D a b instance (D a b, C b c) => D a c data Foo = Foo deriving Show data Bar = Bar deriving Show instance D Foo Foo c :: C x y => x -> y -> () c _ _ = () d :: D x y => x -> y -> () d _ _ = () *Main> d Foo Foo () -- as expected *Main> c Foo (Foo,Bar) () -- as expected *Main> d Foo (Foo,Bar) <interactive>:1:1: Context reduction stack overflow; size = 21 Use -fcontext-stack=N to increase stack size to N [skip] $dD :: D Foo b1 $dD :: D Foo b $dD :: D Foo (Foo, Bar) In the expression: d Foo (Foo, Bar) In an equation for `it': it = d Foo (Foo, Bar) I.e. for some reason on the second step resolver fails to pick up the most specific (and the most obvious) instance D Foo Foo and continues to apply the instance (D a b, C b c) => D a c. Reproduced with GHC 6.12.1 and 7.0.1. -- Roman I. Cheplyaka :: http://ro-che.info/ Don't worry what people think, they don't do it very often.

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panic parsing a stmt in ghc 7 (possible regression?)
by Daniel Gorín 01 Feb '11

01 Feb '11

Hi I'm trying to make the hint library work also with ghc 7 and I'm having problems with some test-cases that are now raising exceptions. I've been able to reduce the problem to a small example. The program below runs ghc in interpreter-mode and attempts to parse an statement using ghc's parseStmt function; the particular statement is a let-expression with a \n in the middle. The observed behaviour is: > $ ghc-6.12.1 -fforce-recomp --make -package ghc -cpp -Wall d.hs && ./d > [1 of 1] Compiling Main ( d.hs, d.o ) > Linking d ... > let {e = let x = () > in x ;} in e > Ok > $ ghc-7.0.1 -fforce-recomp --make -package ghc -cpp -Wall d.hs && ./d > [1 of 1] Compiling Main ( d.hs, d.o ) > Linking d ... > let {e = let x = () > in x ;} in e > d: d: panic! (the 'impossible' happened) > (GHC version 7.0.1 for i386-apple-darwin): > srcLocCol <no location info> > > Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Is it a regression or should I be doing this some other way? Thanks, Daniel -- d.hs import qualified GHC import qualified MonadUtils as GHC ( liftIO ) import qualified StringBuffer as GHC import qualified Lexer as GHC import qualified Parser as GHC import qualified GHC.Paths main :: IO () main = GHC.runGhcT (Just GHC.Paths.libdir) $ do -- initialize df0 <- GHC.getSessionDynFlags _ <- GHC.setSessionDynFlags df0{GHC.ghcMode = GHC.CompManager, GHC.hscTarget = GHC.HscInterpreted, GHC.ghcLink = GHC.LinkInMemory, GHC.verbosity = 0} df1 <- GHC.getSessionDynFlags -- runParser let expr = "let {e = let x = ()\nin x ;} in e" GHC.liftIO $ putStrLn expr buf <- GHC.liftIO $ GHC.stringToStringBuffer expr let p_res = GHC.unP GHC.parseStmt (mkPState df1 buf GHC.noSrcLoc) case p_res of GHC.POk{} -> GHC.liftIO $ putStrLn "Ok" GHC.PFailed{} -> GHC.liftIO $ putStrLn "Failed" where #if __GLASGOW_HASKELL__ >= 700 mkPState = GHC.mkPState #else mkPState = \a b c -> GHC.mkPState b c a #endif

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