- Haskell - Haskell.org

RE: HGL ang GHC on Win32
by Simon Marlow 14 Mar '02

14 Mar '02

> That is a shame. I tried both suggestions (specifying > position explicitly > and recompiling with fvia-c -- i had been using O all along) > and neither > worked :(. > > I also tried using 5.03, and got the following warnings: [ message deleted ] It looks like there are some prototypes missing: > C:\DOCUME~1\hdaume\LOCALS~1\Temp\ghc920.hc:59: warning: implicit > declaration of function `prim_rgb' GHC might not generate correct calls to these functions unless there is a visible prototype. In fact, taking this example, the definition of prim_rgb is DWORD prim_rgb(BYTE arg1,BYTE arg2,BYTE arg3) but its FFI declaration says foreign import ccall "prim_rgb" unsafe prim_rgb :: Word32 -> Word32 -> Word32 -> IO (Word32) this looks a bit strange - is there a green-card expert out there to explain what's going on? Why have the BYTEs been turned into Word32s? Cheers, Simon

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which to download for SuSE7.0
by jeroen kops 14 Mar '02

14 Mar '02

Can I use hugs98 on mij Linux SuSE7.0 computer? If the awnser is yes, which files do I have to download? Greetings, J. Kops Student University Utrecht (The Netherlands) _________________________________________________________________ Download MSN Explorer gratis van http://explorer.msn.nl/intl.asp.

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For the Heskell
by 정종길 14 Mar '02

14 Mar '02

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RE: un-layout program
by Simon Marlow 14 Mar '02

14 Mar '02

> does there exist a program that'll take a layed out haskell > program and > output one that uses braces and semis to delimit? You can use GHC's hssource package to parse & then pretty-print the source code - the pretty printer can generate output with explicit layout tokens if you ask for it. The documentation is a bit lacking (well, there isn't any), so grab the source or browse it on the web here: http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/hslibs/hssource/ Cheers, Simon

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Final CFP: MTV'02 deadline on March 25
by mvelev＠ece.gatech.edu 14 Mar '02

14 Mar '02

Call for Papers ===================================================================== Microprocessor Test and Verification (MTV'02) June 6-7, 2002, Austin, Texas, USA http://ece.tamu.edu/MTV/ ===================================================================== Submission deadline: March 25, 2002 Sponsored by: IEEE Computer Society Test Technology Technical Council General Chair: Magdy S. Abadir (abadir(a)ibmoto.com) Motorola Program Chair: Li-C. Wang (licwang(a)ece.ucsb.edu) UCSB Areas of Interest: -Validation of microprocessors -Experiences on test and verification of high performance processors -Test/verification of multimedia processors -Performance testing -High-level test generation for functional verification -Emulation techniques -Silicon debugging -Formal techniques and their applications -Verification coverage -Test generation at the transistor level -Equivalence checking of custom circuits at the transistor level -Circuit level verification -Switch-level circuit modeling -Timing verification techniques -Path analysis for verification or test -Design error models -Design error diagnosis -Design for testability or verifiability -Optimizing SAT procedures for application to testing and formal verification

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un-layout program
by Hal Daume III 14 Mar '02

14 Mar '02

does there exist a program that'll take a layed out haskell program and output one that uses braces and semis to delimit? - hal -- Hal Daume III "Computer science is no more about computers | hdaume(a)isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume

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RE: HGL ang GHC on Win32
by Simon Marlow 13 Mar '02

13 Mar '02

> I'm hoping that a GHC honcho will say > > "Well of course that happens with 5.02.2 - you should > upgrade to 5.03 right away." > > or some such. I'm afraid not :-) But there *is* a bug in the native code generator in 5.02.2, namly in the FFI support for passing floating point arguments to ccalls, which I fixed yesterday and could potentially cause this kind of problem. Make sure the graphics library has been compiled with -fvia-C or -O to work around it (and if this helps, please let us know). Cheers, Simon

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HGL ang GHC on Win32
by Hal Daume III 13 Mar '02

13 Mar '02

When I compile a program using GHC 5.02.2 on Windows 200 using HGL, using the following command line: > ghc --make HelloWorld.hs -o HelloWorld.exe -package concurrent -package win32 -ic:\GraphicsLibrary\lib\win32 it compiles fine, but then when I run the exe, the window starts out initially as wide as my screen and only as tall as the title bar, regardless of what is passed as the dimensions to openWindow. What gives? If I resize the window everything works fine, but in my own application resizing the window causes it to report some error about arithmetic being bigger than 32 bits... Any ideas? - Hal -- Hal Daume III "Computer science is no more about computers | hdaume(a)isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume

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by Christine Hall 12 Mar '02

12 Mar '02

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RE: Haskell report: deriving Show & Read instances, Appendix D
by Simon Peyton-Jones 12 Mar '02

12 Mar '02

Folks Olaf points out a problem with the specification of 'deriving' Show. In particular: | "The representation will be enclosed in parentheses | if the precedence of the top-level constructor operator in x | is less than d." Olaf proposes that we should change "less than" to "less than or equal to". His reasoning is below, and seems persuasive to me. Briefly, the consequences of the change would be: a) The current specification yields syntactically incorrect Haskell for some associativities. The changed specification would avoid this. b) The changed spec would yield more than the minimum number of parentheses. c) The current spec makes it hard for simple recursive descent parsers, such as that suggested by the Report for Read, to avoid divergence on left recursion. The changed spec makes it easy. d) The downside is that all compilers would need to change, slightly. Any comments? Simon | In all Haskell implementations (tested Hugs,Ghc and nhc98) | show sometimes produces output that does not represent | well-formed expressions. For example: | | data Tree a = Node a | Tree a :^: Tree a | Tree a ::: Tree a | deriving (Eq,Show) | | infixl 6 ::: | infixr 6 :^: | | main = print ((Node True :^: Node False) ::: Node True) | | yields | | Node True :^: Node False ::: Node True | | The expression is ill-formed because one constructor is left- | and the other one is right-associative. | | Finally, left-recursive data constructors that are | left-associative lead read into infinite recursion. Example: | | infixl 5 :^: | | data Tree a = Leaf a | Tree a :^: Tree a deriving (Show,Read) | | main = do | print (read "(Leaf True :^: Leaf False) :^: Leaf True" :: Tree Bool) | | | I have a solution for the two last problems. It means all | Haskell compilers have to change, but I believe that it is worth it. | | The source of the show problem is that show tries to handle | associativity of infix constructors. But there is no way to | do this correctly. showsPrec gets as argument the precedence | of the surounding expression, but not its associativity. This | associativity would be needed to use associativity of | constructors correctly. | | The solution is simple: dont' try to use associativity to | avoid parenthesis. Thus you get some superfluous paranthesis, | but the output is always correct and the implementation of | deriving is even a bit simpler. E.g.: | | showsPrec d (u :^: v) = showParen (d > 5) showStr | where | showStr = showsPrec 6 u . | showString " :^: " . | showsPrec 6 v | For all of | | infix 5 :^: | infixl 5 :^: | infixr 5 :^: | | The second advantage of this simplification is, that the | additional parentheses prevent infinite left recursion. You | can read in the tree expression given above, because | parentheses are now compulsory: | | instance (Read a) => Read (Tree a) where | | readsPrec d r = readParen (d > 5) | (\r -> [(u:^:v,w) | | (u,s) <- readsPrec 6 r, | (":^:",t) <- lex s, | (v,w) <- readsPrec 6 t]) r | | ++ readParen (d > 9) | (\r -> [(Leaf m,t) | | ("Leaf",s) <- lex r, | (m,t) <- readsPrec 10 s]) r | | What do you think? | | Discussing all the other minor problems with the report | specification doesn't make sense before this major issue is | cleared up. | | Ciao, | Olaf | | -- | OLAF CHITIL, | Dept. of Computer Science, The University of York, York YO10 | 5DD, UK. | URL: http://www.cs.york.ac.uk/~olaf/ | Tel: +44 1904 434756; Fax: +44 1904 432767 |

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