April 2002 - Hugs-Bugs

Automaticka odpoved. Automatic Reply.
by alh＠post.cz 22 Apr '02

22 Apr '02

polib mi prdel

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typo in home page
by Alastair Reid 20 Apr '02

20 Apr '02

'Tis a tiny problem but... There's a spelling error in the graphics on the Hugs homepage. Instead of: Dowload the full release of Hugs98 here it should read: Download the full release of Hugs98 here (Spotted while checking into a more serious potential bug in HGL...) -- Alastair Reid reid(a)cs.utah.edu http://www.cs.utah.edu/~reid/

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foreign export dynamic for MacOS X
by Wolfgang Thaller 17 Apr '02

17 Apr '02

I recently added PowerPC thunk creation to GHC, and I thought it would also be useful for hugs. Cheers, Wolfgang Thaller --- for src/builtin.c: struct thunk_data { struct thunk_data* next; struct thunk_data* prev; HugsStablePtr stable; #if defined(__ppc__) char code[13*4]; #else char code[16]; #endif }; struct thunk_data* foreignThunks = 0; static void* mkThunk(void* app, HugsStablePtr s) { struct thunk_data* thunk = (struct thunk_data*)malloc(sizeof(struct thunk_data)); char* pc; if (!thunk) { /* ToDo: better cleanup */ printf("Can't allocate thunk for foreign export dynamic\n"); exit(1); } if (foreignThunks) { /* non-empty list */ foreignThunks->prev = thunk; } thunk->next = foreignThunks; thunk->prev = 0; foreignThunks = thunk; thunk->stable = s; pc = &thunk->code[0]; #if defined(__i386__) /* 3 bytes: pushl (%esp) */ *pc++ = 0xff; *pc++ = 0x34; *pc++ = 0x24; /* 8 bytes: movl s,4(%esp) */ *pc++ = 0xc7; *pc++ = 0x44; *pc++ = 0x24; *pc++ = 0x04; *((HugsStablePtr*)pc)++ = s; /* 5 bytes: jmp app */ *pc++ = 0xe9; *((int*)pc)++ = (char*)app - ((char*)&(thunk->code[16])); #elif defined(__ppc__) && defined(__GNUC__) /* This is only for MacOS X. * It does not work on MacOS 9 because of the very strange * handling of function pointers in OS 9. * I don't know about LinuxPPC calling conventions. * Please note that it only works for up to 7 arguments. */ { unsigned long *adj_code = (unsigned long*)pc; // make room for extra arguments adj_code[0] = 0x7d2a4b78; //mr r10,r9 adj_code[1] = 0x7d094378; //mr r9,r8 adj_code[2] = 0x7ce83b78; //mr r8,r7 adj_code[3] = 0x7cc73378; //mr r7,r6 adj_code[4] = 0x7ca62b78; //mr r6,r5 adj_code[5] = 0x7c852378; //mr r5,r4 adj_code[6] = 0x7c641b78; //mr r4,r3 adj_code[7] = 0x3c000000; //lis r0,hi(app) adj_code[7] |= ((unsigned long)app) >> 16; adj_code[8] = 0x3c600000; //lis r3,hi(s) adj_code[8] |= ((unsigned long)s) >> 16; adj_code[9] = 0x60000000; //ori r0,r0,lo(app) adj_code[9] |= ((unsigned long)app) & 0xFFFF; adj_code[10] = 0x60630000; //ori r3,r3,lo(s) adj_code[10] |= ((unsigned long)s) & 0xFFFF; adj_code[11] = 0x7c0903a6; //mtctr r0 adj_code[12] = 0x4e800420; //bctr pc = (char*) &adj_code[13]; // Flush the Instruction cache: //MakeDataExecutable(adjustor,4*13); /* This would require us to link with CoreServices.framework */ { /* this should do the same: */ int n = 13; unsigned long *p = adj_code; while(n--) { __asm__ volatile ("dcbf 0,%0\n\tsync\n\ticbi 0,%0" : : "g" (p)); p++; } __asm__ volatile ("sync\n\tisync"); } } #else ERRMSG(0) "Foreign export dynamic is not supported on this architecture" EEND; #endif assert(pc <= &thunk->code[0] + sizeof(thunk->code)); return &thunk->code; /* a pointer into the middle of the thunk */ }

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Unexpected "unresolved top-level overloading" error
by Magnus Carlsson 16 Apr '02

16 Apr '02

The following module module Bug where class C a b c | a b -> c where m :: a -> b -> c instance C Integer Integer Integer newtype T a = T a instance C a b c => C (T a) (T b) (T c) i :: T Integer i = undefined x = m (m i i) i generates the following error: $ hugs -98 Bug.hs __ __ __ __ ____ ___ _________________________________________ || || || || || || ||__ Hugs 98: Based on the Haskell 98 standard ||___|| ||__|| ||__|| __|| Copyright (c) 1994-2001 ||---|| ___|| World Wide Web: http://haskell.org/hugs || || Report bugs to: hugs-bugs(a)haskell.org || || Version: December 2001 _________________________________________ Hugs mode: Restart with command line option +98 for Haskell 98 mode Reading file "/usr/share/hugs/lib/Prelude.hs": Reading file "Bug.hs": Type checking ERROR "Bug.hs":16 - Unresolved top-level overloading *** Binding : x *** Outstanding context : C Integer Integer b If the definition of x is changed to x _ = m (m i i) i the module loads and x gets the type Bug> :t x x :: a -> T Integer So it looks like a monomorphism check is carried out too early in the first case. /M

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Aging can be reversed with HGH
by unknown＠example.com 15 Apr '02

15 Apr '02

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bug?
by Pawel Kozak 15 Apr '02

15 Apr '02

hello, i installed HUGS and ran it. it worked without problems, then i installed GHC and an another program, that crashed and forced me to reboot. after i rebooted and tryed to restart HUGS it crashed each time :( i tryed to uninstall it, and to reinstall it many times, but it didnt help, also a registery clean and dll-clean didnt help me out. here is the error message: WINHUGS caused an invalid page fault in module WINHUGS.EXE at 0177:0045910f. Registers: EAX=00000000 CS=0177 EIP=0045910f EFLGS=00010206 EBX=00000001 SS=017f ESP=00bcf3f0 EBP=00000718 ECX=00000000 DS=017f ESI=00f007d0 FS=5a3f EDX=00000071 ES=017f EDI=00000000 GS=0000 Bytes at CS:EIP: 88 10 8a 44 24 6c 88 01 8d 54 24 1c 8d 44 24 24 Stack dump: 00bcf488 00000000 00bcfe38 00000718 02b00371 00000000 00000000 084c1fe6 00000001 00000000 03f902bb 040002ae 001002bf 0000001a 03f90100 00000000 i would be pleased if you check if it is a bug, because i am really excited of HUGS and want to use the windows version. thanks and greets for germany p.Kozak Mit freundlichen Grüßen Pawel Kozak Gründer des IRCLOVE Projekts www.irclove.de ______________________ pawel(a)kozak.de professor(a)irclove.de captnpk(a)hotmail.com

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Derived Show and Read
by Simon Peyton-Jones 11 Apr '02

11 Apr '02

Malcolm, Huggers, Olaf points out that the defn of derived instances of Read in the H98 appendix isn't right. In particular, to avoid problems we should require parentheses when the precedence level doesn't change, even if the associativity could in principle let us do without. I propose to replace the first set of bullets in D.4 with the following, and change the example code to match. (I think I'll make the constructor infixr, just to make the point.) [This replaces my earlier proposal to change 'less than' to 'less than or equal to'.] This change will affect Hugs and nhc: in particular, 'Show' should output parentheses even if associativity might allow them to be omitted. Before enshrining this change I wanted to check that it looks reasonable to you. RSVP Simon ======================== "Derived instances of Read make the following assumptions, which derived instances of Show obey: 1. If the constructor is defined to be an infix operator, then the derived Read instance will parse only infix applications of the constructor (not the prefix form). 2. Associativity is not used to reduce the occurrence of parentheses, although precedence may be. For example, given infixr :$ data T = Int :$ Int then: * "show (1 :$ 2 :$ 3)" produces the string "1 :$ (2 :$ 3)". * (read "1 :$ (2 :$ 3)") succeeds, with the obvious result. * (read "1 :$ 2 :$ 3") fails. 3. Similarly, if the constructor is defined using record syntax, the derived Read will parse only the record-syntax form, and furthermore, the fields must be given in the same order as the original declaration. 4. The derived Read instance allows arbitrary Haskell whitespace between tokens of the input string. Extra parenthese are also allowed." Outside the bullets I'll collect the stuff about Show: "The result of @show@ is a syntactically correct \Haskell{} expression containing only constants, given the fixity declarations in force at the point where the type is declared. It contains only the constructor names defined in the data type, parentheses, and spaces. When labelled constructor fields are used, braces, commas, field names, and equal signs are also used. Spaces and parentheses are only added where needed, ignoring associativity. No line breaks are added. The result of @show@ is readable by @read@ if all component types are readable. (This is true for all instances defined in the Prelude but may not be true for user-defined instances.)"

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Problems with "Hugs for Windows"
by David Gray 10 Apr '02

10 Apr '02

I have students using Hugs for Windows, Version: December 2001. Unfortunately, string handling appears to be somewhat erratic. I have attached one example. If this program is loaded and the following expression evaluated a number of times, each evaluation gives a different (usually wrong) result. dose (p,x) i Everything works correctly with the command-line version of HUGS. Thank you for your time. David Gray

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Re: bug neither fixed nor listed as known
by Alastair Reid 09 Apr '02

09 Apr '02

> [...] Sir Jeffrey Lewis [...] And there I was thinking that article 1 of the US constitution forbad citizens from accepting "any present, emolument, office, or title, of any kind whatever, from any king, prince, or foreign state." :-) -- Alastair Reid

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bug neither fixed nor listed as known
by Ralf Laemmel 09 Apr '02

09 Apr '02

Dear Hugs-Bugsers, As reported in Sep. last year, there is very serious problem in hugs when it comes to class hierarchies. See the program below. Is anyone maintaining hugs and paying attention to incoming bug reports? Thanks, Ralf import Monad class Monad m => C1 m x -- Monad m is implied by C1 but test diverges if constraint not present class (C1 m x) => C2 m x where c2 :: x -> m x instance Monad m => C1 m Bool instance C2 Maybe Bool where c2 = return test :: Maybe Bool test = c2 True -- Dr.-Ing. Ralf Laemmel CWI & VU, Amsterdam, The Netherlands http://www.cwi.nl/~ralf/ http://www.cs.vu.nl/~ralf/

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