Here is the latest Caml Weekly News, for the week of 15 to 22 November, 2005.
Archive: http://thread.gmane.org/gmane.comp.lang.caml.general/31244Daniel Margolis asked and Richard Jones answered:
> With some help, I've managed to get OCaml-MySQL working. But if > anyone has any other recommendations of database libraries, still > feel free to share them with me. ocamldbi has a MySQL interface. http://savannah.nongnu.org/download/modcaml/David Baelde then said:
It may be worth pointing that ocaml-mysql is not thread-ready. I reported that a few months ago and nothing was done. The problem is that the bindings do not declare blocking sections, so when one thread calls a mysql function (which can take time) the other threads won't be scheduled. I'm glad to hear about ocamldbi. Is it well maintained ? has blocking sections stuff ? If so, we (savonet.sf.net) should swicth to it.
There were several threads about Sudoku, you may find them here: http://thread.gmane.org/gmane.comp.lang.caml.general/31252 http://thread.gmane.org/gmane.comp.lang.caml.general/31302 http://thread.gmane.org/gmane.comp.lang.caml.general/31389 http://thread.gmane.org/gmane.comp.lang.caml.general/31391 http://thread.gmane.org/gmane.comp.lang.caml.general/31395 Next are some short extracts, with most of the discussions removed.Alain Frisch said:
Funny. My father told me about the game last sunday and I was willing to write a solver too :) Here it is: http://www.eleves.ens.fr/home/frisch/info/af-sudoku-brute.ml http://www.eleves.ens.fr/home/frisch/info/af-sudoku.mlDiego Olivier Fernandez Pons said:
There is a nice paper by Helmut Simonis "Sudoku as a constraint problem" with reference to the relevant paper for the algorithms. http://www.icparc.ic.ac.uk/~hs/David Thomas said:
Mostly to teach myself Ocaml and Tk, I put together a simple Sudoku game. If anyone wants to play with it, modify it, etc, feel free. http://people.ucsc.edu/~dlthomas/sudoku.ml The puzzle generation at present is entirely braindead, but if someone produces a nice solution, I'd love to see it included.Alain Frisch said:
Follow-up to the recent discussion here: I've improved my Sudoku solver and released it with some documentation http://www.eleves.ens.fr/home/frisch/sudoku.html It was able to deal in reasonnable time with all the 3x3, 4x4 and 5x5 grids I could find (often <10ms for 3x3 grids). Some difficult puzzles are included in the distribution.Jon Harrop said:
In the face of stiff competition, I have updated my Sudoku solver in OCaml with a new implementation that is shorter, simpler and faster (although nothing like as fast as Alain's): http://www.ffconsultancy.com/free/sudoku/ I have also included links to Sudoku solvers written in OCaml by Alain Frisch, Pascal Brisset and David Thomas.Arthur Chargueraud said:
Well, if you are interested, you may wish to have a look at my: - thirteen lines of Caml (though my lines are not so short) - of a rather efficient sudoku solver - that gives all solution for an input grid - and uses only modules Pervasive and Array. Thanks Caml ! You may find it here: http://arthur.chargueraud.org/divers/sudoku/ I haven't done any advanced benchmarking, but it looks like my code isn't too slow.Marco Maggesi said:
include Set.Make(struct type t = (int * int) * int let compare = compare end) let (@) g f x = g (f x) and id x = x and sw f x y = f y x and zip x y = (x, y) let fold9 f = let rec loop i = if i>8 then id else loop (i+1) @ f i in loop 0 let fold81 f = fold9 (fold9 @ (@) f @ zip) let mark ((i,j),x as e) : t -> t = add e @ fold9 (fun k -> remove ((i/3*3 + k/3, j/3*3 + k mod 3), x) @ remove ((i,j),k) @ remove ((i,k),x) @ remove ((k,j),x)) let search = let g p f s = fold (f @ sw mark s) (filter ((=) p @ fst) s) in fold81 g let read () = let f p = Scanf.scanf "%d " (fun x -> if x>0 then mark (p,x-1) else id) in fold81 f (fold81 (fold9 @ ((@) add @ zip)) empty) let print s () = let pr ((i,j),x) = Printf.printf "%d%c" (x+1) (if j=8 then '\n' else ' ') in iter pr s; print_newline ();; search print (read ()) ();;
Archive: http://thread.gmane.org/gmane.comp.lang.caml.general/31298Richard Jones said:
Why is CODE32 defined on the x86-64 architecture? This architecture has 64 bit pointers, and it seems like it's only by luck that the bytecode interpreter normally works. In particular, if you have the interpreter in a shared library, or (I assume) address-space randomization, then the jump table is located above the 4GB boundary, and the bytecode interpreter segfaults as soon as it tries to jump to the first instruction. I had to apply the following patch to allow the bytecode interpreter to work in a shared library: --- ocaml-3.09.0.orig/configure 2005-09-24 10:19:09.000000000 +0100 +++ ocaml-3.09.0/configure 2005-11-16 14:59:56.000000000 +0000 @@ -291,9 +291,7 @@ exe=".exe" ostype="Cygwin";; gcc*,x86_64-*-linux*) - bytecccompopts="-fno-defer-pop $gcc_warnings" - # Tell gcc that we can use 32-bit code addresses for threaded code - echo "#define ARCH_CODE32" >> m.h;; + bytecccompopts="-fno-defer-pop $gcc_warnings";; gcc*) bytecccompopts="-fno-defer-pop $gcc_warnings";; esacXavier Leroy answered:
No, it's not by luck: the x86-64 ABI defines several "code models", one of which -- the "small code model" -- guarantees that code and static data is in the lower 2G of the address space, and is the default for gcc (and I suspect other compilers as well). I would have expected the dynamic loader to implement the small model like the static linker does, but from what you say it's not the case.
Archive: http://thread.gmane.org/gmane.comp.lang.caml.general/31281Jonathan Roewen asked and Damien Doligez answered:
> I have a simple ML file (test.ml): > > external raise : exn -> 'a = "%raise";; > > raise End_of_file;; > > so I can check how the compiler does things (like if predefined ocaml > symbols are still present without stdlib present), and compile as: > > ocamlc -nostdlib -nopervasives test.ml, which generates a.out. > > when I run it, I get error: "-bash: ./a.out: cannot execute binary > file" (btw, generates expected behabiour without those flags) > > why can't it execute it? can we only use -nostdlib as long as we > provide our own pervasives module? Note that a.out is still a valid bytecode file: ocamlrun ./a.out works. What happens is that ocamlc tries to create an executable bytecode file, by prepending the standard header (#!/usr/local/bin/ocamlrun) to your bytecode file. But it can't find this header because you have specified -nostdlib, thus preventing it from looking in its library directory. It explicitely ignores the "file not found" error, I'm not sure why. What you can do is provide your own header file, named "camlheader", and placed in one of the directories searched by ocamlc. If you don't give any -I option, this has to be the current directory: $ echo '#!/bin/echo foo' >camlheader $ ocamlc -nostdlib -nopervasives test.ml $ ./a.out foo ./a.out
Archive: http://thread.gmane.org/gmane.comp.lang.caml.general/31355Matt Gushee announced:
Some time ago on this list, there was a discussion of the pros and cons of the Tk GUI toolkit. In the course of that discussion I claimed that Tk could be made significantly less ugly ... someone asked how, but I never answered--sorry! At any rate, here, finally, is the answer: http://matt.gushee.net/rg/items/4
Archive: http://thread.gmane.org/gmane.comp.lang.caml.general/31365Xavier Leroy announced:
The bug tracking system for Caml now uses Mantis in replacement for Jitterbug, which was increasingly showing its age. The new BTS should make it much easier to classify bug reports, add follow-ups and attachments, and be notified of actions taken by the Caml maintainers. However, bug submission can no longer be done by e-mail; please use the Web interface exclusively. Many thanks to Maxence Guesdon for installing Mantis and re-importing the old bug reports.
Archive: http://thread.gmane.org/gmane.comp.lang.caml.general/31429Jon Harrop announced:
Chapter 1 of "Objective CAML for Scientists" is now available on-line as a web page: http://www.ffconsultancy.com/products/ocaml_for_scientists/chapter1.html
Archive: http://thread.gmane.org/gmane.comp.lang.caml.general/31433Mike Lin announced:
Brace yourselves for "The Whitespace Thing". This is an OCaml preprocessor that uses your indentation to group expressions, like in Python and Haskell. Effectively, the preprocessor auto-parenthesizes expressions that are split over multiple lines, using your indentation as clues. This eliminates syntax clutter such as multi-line parenthesizations, the sequencing operators ; and ;; , and the keywords done, end, and begin. http://people.csail.mit.edu/mikelin/ocaml+twt/
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