Re: [Caml-list] Re: Being aware of memory overuse
Sylvain Le Gall sylv...@le-gall.net writes: On 05-02-2010, David Rajchenbach-Teller david.tel...@mlstate.com wrote: Dear list, I'm writing some code that needs to be able to cope nicely with memory exhaustion. That is, it should be able to detect at some point if it is getting close to exhausting memory, and take the necessary course of action (e.g. bailing out nicely). I'm wondering what's the best way of doing this. I've been thinking about installing a [Gc.alarm] and checking [Gc.free_words], [Gc.free_blocks], [Gc.largest_free] just after each major cycle, but I'm wondering if it's the best technique. Any suggestion? I worked on this subject, for a tool that need to use as much memory as possible. I started by trying to use Gc module. I ended by reading /proc/meminfo and getting/checking data from there. It is fast, simple and very precise. In particular, it can take into account other processes that take memory. Regards, Sylvain Le Gall I always wanted to have kernel spport for this. Some way for aplication to tell the kernel about freeable memory and for the kernel to request some memory to be freeed instead of swapping it out. This would be usefull for e.g. a web browser that caches images and rendered pages in memory for quick redraws and many other applications. MfG Goswin ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
Re: [Caml-list] Preventing values from escaping a context
Rich Neswold rich.nesw...@gmail.com writes: On Tue, Feb 9, 2010 at 12:45 PM, Tiphaine Turpin tiphaine.tur...@irisa.fr wrote: Here is an adaptation of your example. Thank you! I'll experiment with your example to see if I can use it (like you said, it may be too complicated to add to the API.) Regardless, it was an interesting lesson and taught me a little more about the language. Thanks again, Why not make the context a custom block with finalizer? The finalizer then frees the resources. If the context escapes then it remains alive and the finalizer will not be called any time soon. Only when it is no longer reachable. That would also allow someone to create a context and use it for a number of operations before forgeting it. The drawback is that the finalizer will only be called when the GC runs at some later time. If you need the resources to be freed right there then it won't help. MfG Goswin ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
Re: [Caml-list] The need to specify 'rec' in a recursive function defintion
# let y = z z ;;
val y : (('_a - '_b) - '_a - '_b) - '_a - '_b = fun
Can anyone get rid of the pesky underscores in the type of y above, so
that it becomes truly polymorphic?
Eta expansion does it...
# let y x = z z x;;
val y : (('a - 'b) - 'a - 'b) - 'a - 'b = fun
Regards,
François
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Re: [Caml-list] The need to specify 'rec' in a recursive function defintion
Andrej Bauer andrej.ba...@andrej.com wrote:
What Gerd probably meant was that the usual untyped lambda-calculus
definition of y, which gets us recursion out of nothing isn't typeable
because self-application requires unrestricted recursive types.
Fortunately, even that is not quite correct: Y is perfectly typable in
plain ML, you just need to introduce the recursive type it employs
explicitly:
type 'a fix = Fix of ('a fix - 'a)
let fix f = let z = fun (Fix g' as g) x - f (g' g) x in z (Fix z)
Now, for example:
let fac = fix (fun fac n - if n = 0 then 1 else n * fac (n-1))
let n = fac 7
Best,
/Andreas
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Re: [Caml-list] The need to specify 'rec' in a recursive function defintion
Jon Harrop: On Tuesday 09 February 2010 22:01:03 Gerd Stolpmann wrote: In the ML community it is consensus that a recursive function is a total different thing than a non-recursive function... Note that Standard ML does this differently to CAML/OCaml. Not quite -- SML simply defines fun f x = ... to be an abbreviation for val rec f = fn x = /Andreas ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
Re: [Caml-list] Re: Being aware of memory overuse
Hi, I always wanted to have kernel spport for this. Some way for aplication to tell the kernel about freeable memory and for the kernel to request some memory to be freeed instead of swapping it out. If I recall correctly, there was an Lwn.net article reporting a lkml (the Linux kernel mailing list) discussion on that subject. One of the proposals was for the kernel to send processes a signal (SIGFREE?) requesting they free up memory (by running a major GC, for example) whenever memory was running low. In theory this could in some cases avoid the invocation of the draconian OOM killer. Question: just how effective such a feature would be in the Ocaml case? Best regards, Dario Teixeira ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
[Caml-list] [Ann] OCamlSpotter 1.1rc2 for OCaml 3.11.2
Hi Caml-list, I have updated OCamlSpotter, a compiler enhancement for source code browsing, to version 1.1rc2, which is aimed for OCaml 3.11.2 and some enhancements since its first release. OCamlSpotter is a tool which finds definition places of various names (identifiers, type names, modules, etc) in OCaml programs automatically for you. The original OCaml's -annot option provides the same sort of functionality but OCamlSpotter provides much more powerful browsing: it can find definitions hidden in the deep nested module aliases and functor applications. - The -annot option of ocamlc and ocamlopt is extended and creates module.spot files (module.spit for .mli), which record the location information of the names defined and used in the module. - A small application ocamlspot provides automatic where-about spotting of the definition of the name you are interested in, using module.spot files created by the patched compilers. - ocamlspot.el provides interactive ocaml-spotting of definition locations in emacs. - Interfaces for other editors such as vi could be built easily, if you want. This release of OCamlSpotter is quite near to 1.1, but still in a RC state. It will become the real 1.1 after 1 or 2 weeks with minimum bug fixes. Further information and download is available at: http://jun.furuse.info/hacks/ocamlspotter Happy hacking. Jun ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
[Caml-list] Re: Being aware of memory overuse
On 10-02-2010, Dario Teixeira darioteixe...@yahoo.com wrote: Hi, I always wanted to have kernel spport for this. Some way for aplication to tell the kernel about freeable memory and for the kernel to request some memory to be freeed instead of swapping it out. If I recall correctly, there was an Lwn.net article reporting a lkml (the Linux kernel mailing list) discussion on that subject. One of the proposals was for the kernel to send processes a signal (SIGFREE?) requesting they free up memory (by running a major GC, for example) whenever memory was running low. In theory this could in some cases avoid the invocation of the draconian OOM killer. Question: just how effective such a feature would be in the Ocaml case? I forgot to tell about other paths I have followed: setrlimit/getrlimit. There are limits like RLIMIT_DATA, RLIMIT_RSS et al (CPU...). setrlimit limits memory by generating ENOMEM when limits are reached and getrlimit should give information about the current level of use of these limits. Unfortunately, the memory consumption I get with getrlimit is not accurate (in fact not updated). I have OCaml bindings for this, I should published in a near future. Regards, Sylvain Le Gall ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
Re: [Caml-list] An extended comparative study of language support for generic programming
On Wednesday 10 February 2010 23:00:44 Raoul Duke wrote: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.110.122rep=rep1 type=pdf :-) http://groups.google.com/group/comp.lang.functional/browse_thread/thread/d6 54fedd6efdf753/3ee82770d5e79402#3ee82770d5e79402 See my response there: http://groups.google.com/group/comp.lang.functional/msg/2cb15a6281087b04 :-) I was wondering if anyone here was familiar with this work and/or had anything to say about their OCaml solutions and discussion? -- Dr Jon Harrop, Flying Frog Consultancy Ltd. http://www.ffconsultancy.com/?e ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
Re: [Caml-list] llvm?
On Wednesday 10 February 2010 22:51:33 Raoul Duke wrote: hi, any news about / anybody working on ocaml-on-llvm? I don't believe anyone is working on porting OCaml to LLVM. The nearest work is probably my own HLVM project which reached a major milestone recently and is now capable of high-performance parallel programming: http://flyingfrogblog.blogspot.com/2010/01/naive-parallelism-with-hlvm.html From the point of view of an OCaml programmer, HLVM is a DSL that drops various features from OCaml (e.g. polymorphic recursion) in order to provide easily-obtained, predictable and high performance. -- Dr Jon Harrop, Flying Frog Consultancy Ltd. http://www.ffconsultancy.com/?e ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
Re: [Caml-list] Re: The need to specify 'rec' in a recursive function defintion
On Wednesday 10 February 2010 22:25:44 Till Varoquaux wrote: Some (including me) would even argue that it is sad that type definitions don't use rec. Agreed. Less useful than rec on function definitions but that would still be useful sometimes. -- Dr Jon Harrop, Flying Frog Consultancy Ltd. http://www.ffconsultancy.com/?e ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
[Caml-list] Ocaml, Objective-c, and XCode
Hi there, I have a few questions relating to using Ocaml with objective-c for anyone who programs on a Mac. I am aware that there aren't any real bindings between ocaml and objective-c/cocoa, so I am investigating rolling my own. So: 1) Does anyone have experience in interfacing ocaml and objc? Is it difficult? 2) Does anyone have a small example project that does mix these two languages? I have looked at unison, but it is too big for me to get my head around. I am thinking more on the scale of the ubiquitous Currency Converter... 3) Does anyone who is mixing these languages use Xcode to do so? If so, what steps do you need to go through to set that up? A big thanks to anyone who can answer (some of) these questions. I am trying to decide whether to use haskell or ocaml for my next cocoa application, as these are the two languages I am most comfortable. I have recently found an excellent description of how to do this using haskell (http://tscheff.blogspot.com/2010/02/currync-converter-using-haskell-with.html) and was wondering if there were such resources for ocaml. Thanks, Andrew ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
[Caml-list] Re: The need to specify 'rec' in a recursive function defintion
Fortunately OCaml is (much more) than simply-typed lambda calculus. Almost any feature of OCaml -- recursive data types, recursive types, reference cells, mutable records, exceptions, objects, recursive modules and polymorphic variants -- can be used to express the fixpoint combinator. Sometimes there is more than one way to use the same feature to express the fixpoint combinator. The more and less known ways of expressing fix are collected in the following document: http://okmij.org/ftp/ML/fixpoints.ml ___ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
