- Haskell-Cafe - Haskell.org

Announcement: Beta of Leksah IDE available
by Jürgen Nicklisch-Franken 04 Apr '09

04 Apr '09

I'm proud to announce release 0.4.4 of Leksah, the Haskell IDE written in Haskell. Leksahs current features include: * On the fly error reporting with location of compilation errors * Completion * Import helper for constructing the import statements * Module browser with navigation to definition * Search for identifiers with information about types and comments * Project management support based on Cabal with a visual editor * Haskell customised editor with "source candy" * Configuration with session support, keymaps and flexible panes For further information: leksah.org Please don't compare what we have reached to IDE's like VisualStudio, Eclipse or NetBeans. I started Leksah June 1997 and work on it in my spare time for fun. I started the project for various reasons. One was to contribute to make Haskell successful in industry, because I suffer from the use of inappropriate programming languages like C, C++, C# or Java in my daily job. Another was to contribute to open source, which I'm using privately almost exclusively. The first alpha version of Leksah was published February 2008. Since the beginning of this year Hamish Mackenzie joined the project and merged his Funa project with Leksah, which gave a real boost. I thank the people who have encouraged and helped me with their comments, enthusiasm and support. I learned as well that the IDE issue is a controversial theme in the community. I learned that "IDEs are big evil nasty things", that "if you need an IDE, something is wrong with your language", that it is scientifically proved, that "real cool hackers will always use Emacs or vi". Most stupid I found the recurring comment: "Every few years there is someone who starts a Haskell IDE project and then gives up after a few years.". That will be true for Leksah as well, if it will not be accepted and supported by the community. The current state of Leksah is a proof of concept, that an IDE for Haskell is not a difficult thing to do if the community supports it and that it will in my view be of great help and will contribute tremendously to spread Haskell. So I please the members of the community to pause for a moment and try out Leksah with a benevolent attitude. Jürgen Nicklisch-Franken

11 19

.editrc
by brad clawsie 04 Apr '09

04 Apr '09

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 does anyone have a .editrc they can provide that allows ghci to be used on freebsd? i'm not looking for anything fancy, just backspace not being broken etc thanks brad -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (Darwin) iEYEARECAAYFAknVGdQACgkQxRg3RkRK91NZ4gCgm8Oktcs3sCYl6YoY6X4igZAR IDIAn2cpF7QnI4zz4LFN1cVlzG7qSHHk =CJXp -----END PGP SIGNATURE-----

2 1

First time I've gotten gtk2hs to install from ports on Mac OS X from scratch
by Jeff Heard 04 Apr '09

04 Apr '09

The instructions in the leksah manuals seem to work for doing a straight-up ports install of gtk2hs. I've never managed to get it to install without compiling manually, but this worked $ sudo port install gtk2 cairo librsvg libglade2 gtksourceview2 gtkglext gtk-chtheme gtk2-clearlooks $ sudo port -k install ghc gtk2hs hs-cabal Unfortunately leksah itself won't link...

2 2

Leksah+Gtk2Hs link error on Mac OS X Leopard
by Jeff Heard 04 Apr '09

04 Apr '09

I tried installing leskah on OS X using the x11 version of gtk2hs (because I use gtkglext a lot in my work, and need it, therefore the quartz build won't work for me) I get these errors. Is this leksah specific or is this a more general problem with gtk2hs? Linking dist/build/leksah/leksah ... ld warning: atom sorting error for _ghczm6zi10zi1_LibFFI_Czuffizutype_closure_tbl and _ghczm6zi10zi1_LibFFI_Czuffizucif_closure_tbl in /opt/local/lib/ghc-6.10.1/ghc-6.10.1/libHSghc-6.10.1.a(LibFFI.o) ld warning: atom sorting error for _ghczm6zi10zi1_LibFFI_Czuffizutype_closure_tbl and _ghczm6zi10zi1_LibFFI_Czuffizucif_closure_tbl in /opt/local/lib/ghc-6.10.1/ghc-6.10.1/libHSghc-6.10.1.a(LibFFI.o) $ ~/.cabal/bin/leksah dyld: lazy symbol binding failed: Symbol not found: _cairo_quartz_font_face_create_for_atsu_font_id Referenced from: /opt/local/lib/libpangocairo-1.0.0.dylib Expected in: /opt/local/lib/libcairo.2.dylib dyld: Symbol not found: _cairo_quartz_font_face_create_for_atsu_font_id Referenced from: /opt/local/lib/libpangocairo-1.0.0.dylib Expected in: /opt/local/lib/libcairo.2.dylib Trace/BPT trap

1 0

about Haskell code written to be "too smart"
by Manlio Perillo 04 Apr '09

04 Apr '09

Hi. In these days I'm discussing with some friends, that mainly use Python as programming language, but know well other languages like Scheme, Prolog, C, and so. These friends are very interested in Haskell, but it seems that the main reason why they don't start to seriously learning it, is that when they start reading some code, they feel the "Perl syndrome". That is, code written to be "too smart", and that end up being totally illegible by Haskell novice. I too have this feeling, from time to time. Since someone is starting to write the Haskell coding style, I really suggest him to take this "problem" into strong consideration. Manlio

40 124

happstack example code wanted
by Johannes Waldmann 04 Apr '09

04 Apr '09

Hi, I'm thinking of using happstack for a simple online registration system. [ Customer gives Name and Address and registers for certain workshops. Then the app server should just produce a bill. (Payment is handled through a different channel.) The "store owner" needs to get some overview of registrations. ] According to happs(tack) marketing department, this should be an easy exercise? Any code that I could use as a starting point? ( Or, if you do the coding, I can link to you from the workshop site. But I don't have a serious budget :-) Thanks - J.W.

3 2

ANN: logfloat 0.12.0.1
by wren ng thornton 04 Apr '09

04 Apr '09

-------------------------------------------- -- logfloat 0.12.0.1 -------------------------------------------- This package provides a type for storing numbers in the log-domain, primarily useful for preventing underflow when multiplying many probabilities as in HMMs and other probabilistic models. The package also provides modules for dealing with floating numbers correctly. -------------------------------------------- -- Now using FFI -------------------------------------------- We now use the FFI to gain access to C's accurate log1p (and expm1) functions. This greatly increases the range of resolution, especially for very small LogFloat values. These are currently exposed from Data.Number.LogFloat, though they may move to a different module in future versions. On GHC 6.10 the use of -fvia-C had to be disabled because it conflicts with the FFI (version 0.12.0.0 still used it, which is fine on GHC 6.8). I'm still investigating the use of -fasm and getting proper benchmarking numbers. Contact me if you notice significant performance degradation. Using the FFI complicates the build process for Hugs; details are noted in the INSTALL file. It may also complicate building on Windows (due to ccall vs stdcall), though I'm not familiar with Windows FFI and don't have a machine to test on. The calling convention is "unsafe" in order to avoid overhead. However, in the past this has been noted to cause issues with multithreaded applications since it locks all RTS threads instead of just the calling thread. If you're using logfloat in a multithreaded application and notice a slowdown, or if you're more familiar with these details than I, tell me so I can fix things. If you have any difficulties with the FFI, let me know. As an interim solution the FFI can be disabled by turning off the useFFI Cabal flag during configure, which will compile the package to use the naive log1p implementation from earlier versions. -------------------------------------------- -- Other changes since 0.11.0 -------------------------------------------- * (0.11.1) Felipe Lessa added an instance for IArray UArray LogFloat. On GHC we use newtype deriving; On Hugs we fall back to unsafeCoerce to distribute the newtype over IArray UArray Double. * (0.11.2 Darcs) Moved the log/exp fusion rules from Data.Number.LogFloat into Data.Number.Transfinite where our log function is defined. * Added a Storable LogFloat instance for GHC. No implementation is available yet for Hugs. * Removed orphaned toRational/fromRational fusion rules, which were obviated by the introduction of the Data.Number.RealToFrac module in 0.11.0. * Changed the Real LogFloat instance to throw errors when trying to convert transfinite values into Rational. -------------------------------------------- -- Compatibility / Portability -------------------------------------------- The package is compatible with Hugs (September 2006) and GHC (6.8, 6.10). For anyone still using GHC 6.6, the code may still work if you replace LANGUAGE pragma by equivalent OPTIONS_GHC pragma. The package is not compatible with nhc98 and Yhc because Data.Number.RealToFrac uses MPTCs. The other modules should be compatible. -------------------------------------------- -- Links -------------------------------------------- Homepage: http://code.haskell.org/~wren/ Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/logfloat Darcs: http://code.haskell.org/~wren/logfloat/ Haddock (Darcs version): http://code.haskell.org/~wren/logfloat/dist/doc/html/logfloat/ -- Live well, ~wren

4 5

about import alias
by Manlio Perillo 04 Apr '09

04 Apr '09

Hi. Haskell 98 allows import alias: import qualified VeryLongModuleName as C however it does not allow aliasing for imported names import NormalModule (veryLongFunctionName as C) what is the rational? IMHO this can be very useful in some cases. Thanks Manlio

4 3

Re: [Haskell-cafe] How to get glyph outline from ttf font.
by Tillmann Vogt 04 Apr '09

04 Apr '09

Dmitry V'yal schrieb: > Greetings. I'm trying to render some glyphs from ttf font to svg > image using gtk2hs cairo binding. Since I can find nothing appropriate > in gtk2hs API, I decided to draw outlines with bezier curves myself. > But how to get them out of font? As far as I know, freetype library is > capable of extracting outlines, but is there any haskell binding for it > which supports this functionality? > > Here [1] one such lib was mentioned, but it wasn't availible online > that time. Have situation changed today? > > Thanks in advance > > [1] > http://www.nabble.com/Re%3A-Rendering-TTF-fonts-in-Haskell-and-OpenGL-p1563… > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe Hi Dmitry, I cannot help you directly with freetype. But I have developped a library that parses the svg-font format (this is not svg). Since svg-font is XML it is much easier to parse than ttf. There is also a program called fontforge that can be used to convert nearly every format into svg-font. The only problem is that currently triangulation has some bugs and is only O(n^2), the algorithm for deleting holes is not finished, and memoization isn't implemented. Should I upload the work although it is not finished?

1 0

g++ std:map vs GHC IntMap
by Manlio Perillo 04 Apr '09

04 Apr '09

Hi. I have tried to compare performance of the g++ std::map versus the GHC IntMap. The test consists in adding 10000000 elements to an empty map. Haskell code is here: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2899 C++ code is here: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2900 The execution time and CPU usage is almost the same. However the C++ version requires 305 MB, the GHC version 617 MB. gcc 4.3.2 ghc 6.8.2 on Debian Linux Lenny, i386. Isn't really possible to optimize memory usage in cases like this? I also tried with Data.HashTable: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2902 but memory usage is 703 MB, and execution time is about 4.5 times slower! Thanks Manlio Perillo

6 11