February 2002 - Haskell-Cafe

RE: character syntax
by Simon Marlow 08 Feb '02

08 Feb '02

> itz> All this taken together, I mean, _really_, is the lexical > itz> structure of Haskell a botch, or what? > > Jon> No. Innovative. All the problems described in this thread reflect > Jon> unwarranted assumptions inherited in emacs. It's plainly possible > Jon> to parse Haskell, and not hard either. > > First, parsing of a complete program (eg. by a compiler) is quite > different from parsing a buffer that is being edited by a human. The > latter is hard, even for fairly well-specified languages. > Irregularities only make it harder. For syntax highlighting you only need to lexically analyse the buffer, not parse it. Haskell's lexical syntax is parseable by regular expressions, which means it shouldn't be hard to plug a syntax highlighter for Haskell into just about any editor. I don't understand why you say that parsing a buffer being edited by a human is hard - perhaps doing incremental lexing is slightly harder than whole-file lexing, but not that much harder. The "state" of a Haskell lexer can be represented with a little trickery by an integer, so it isn't hard to cache the lexer's state at the beginning of each line. I did this once as an experiment when I added Haskell syntax highlighting to one of the KDE editors (I forget which). The problem is not Haskell, it's emacs. Emacs's syntax highlighting has fairly deeply-wired-in assumptions about C-like languages (eg. last I looked you still couldn't support nested comments properly in font-lock). Cheers, Simon

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win32 stand alone binaries?
by Brett Morgan 08 Feb '02

08 Feb '02

Is it possible to build win32 stand alone binaries using cygwin hosted ghc tools? I know in some ways this is sacriligous to the many unix die hards out there (myself included) - but some of the algorithm's i'm contemplating could possibly turn out to be useful for the "unwashed masses" if a wimp binary could be produced. And I really don't want to go back to c++ for reasons i'm sure most people here are familiar with... brett -- email: Brett.Morgan(a)uts.edu.au phone: 0416-241-898 magic: 153 2 8 105 225 You just come along with me and have a good time. The Galaxy's a fun place. You'll need to have this fish in your ear. Q: What is the shortest lie in computing? A: It works. -- Matthias Felleisen

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Re: compiling hdirect
by Sigbjorn Finne 04 Feb '02

04 Feb '02

Johannes Goetx info(a)polirami.de writes: > ... > gcc -O -mno-cygwin -mwin32 -c mkNativeInfo.c -o mkNativeInfo.o > mkNativeInfo.c:0: malformed option `-D __WIN32__-DWIN32' ... > > malformed option `-D __WIN32__-DWIN32' > > Where can I change this? I could not find a file containing this > option string. Hi, you're using a version of gcc with a broken 'specs' file. Locate the specs file inside your cygwin(?) install tree & change the portion of the "*cpp:" section which expands -mwin32 and -mno-cygwin to the following: %{mwin32|mno-cygwin:-DWIN32 -D_WIN32 -D__WIN32 -D__WIN32__ -DWINNT } i.e., add a space after -DWINNT and the '}' This issue will soon go away, as the use of -mwin32 in GHC's fptools/ tree is in the process of being nuked. hth --sigbjorn

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Re: using composition with multiple argument functions
by Ashley Yakeley 03 Feb '02

03 Feb '02

[Moved to Cafe] At 2002-02-02 17:42, Dean Herington wrote: >With `h1 f g = f # g` and the type >declaration for h1, the compiler sees that f1 and g1 must be used at the >same type. With `h1 = f1 # g1`, that connection is missing. Yes. Haskell cannot be sure that the last instance declaration is the one it wants, because, even though it would work, there might be other possible instance declarations that could apply. Here's a simpler example: -- class C f where foo :: f -> Bool instance C (Bool->Bool) where foo f = f True instance C (Int->Int) where foo f = False f :: Bool f = foo id -- Either instance declaration would work, but Haskell needs one unambiguously for the general type of 'id'. You can fix it by restricting the type of 'id': -- f :: Bool f = foo (id :: Int -> Int) -- >So I guess my `Composable` class example can't work in general. Maybe, maybe not. -- Ashley Yakeley, Seattle WA

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compiling hdirect
by Johannes Goetz 02 Feb '02

02 Feb '02

Hi! Just tried to compile hdirect... ;-) $ make boot make -C src boot && make -C src all make[1]: Entering directory `/home/Administrator/fucker/hdirect/src' rm -f Version.hs echo "--Automatically generated" > Version.hs echo "module Version where" >> Version.hs echo "" >> Version.hs echo "pkg_name :: String" >> Version.hs echo "pkg_name = \"HaskellDirect (ihc.exe)\"" >> Version.hs echo "pkg_version :: String" >> Version.hs echo "pkg_version = \"snapshot 020202\"" >> Version.hs gcc -O -mno-cygwin -mwin32 -c mkNativeInfo.c -o mkNativeInfo.o mkNativeInfo.c:0: malformed option `-D __WIN32__-DWIN32' make[1]: *** [mkNativeInfo.o] Error 1 make[1]: Leaving directory `/home/Administrator/fucker/hdirect/src' make: *** [boot] Error 2 malformed option `-D __WIN32__-DWIN32' Where can I change this? I could not find a file containing this option string. Thanks, Johannes

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Re: functions not in type classes
by Yoann Padioleau 02 Feb '02

02 Feb '02

"Cagdas Ozgenc" <co19(a)cornell.edu> writes: > Greetings. > > Why does Haskell let you write functions that are not a part of type class? > For example instead of the goal of type class is to allow overloading of function, so for example id x = x is not subject to overloading => no use to put it in a type class. > > elem :: Eq a => a -> [a] -> Bool > map :: (a -> b) -> [a] -> [b] > > class Container a where > elem :: Eq b => b -> a b -> Bool > map :: (b -> c) -> a b -> a c > > would define methods that can work on all containers, and create a > discipline to write more reusable and generic functions. yes, that's right that map and elem could be put in a type class, but that's hard and require more advanced feature of haskell (here you use constructor class but you need more : multi-parameter class, ....) see http://www.cse.ogi.edu/~mpj/fds.html. > > Thanks > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- Yoann Padioleau, INSA de Rennes, France, Opinions expressed here are only mine. Je n'écris qu'à titre personnel. **____ Get Free. Be Smart. Simply use Linux and Free Software. ____**

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