Re: [Ur] Drop of several orders of magnitude in Techempower benchmarks
> Hello! I used "git bisect" to find the commit that introduced > behaviour that causes Ur/Web to fail the Fortunes test in the > benchmarks. It's commit 5cc729b48aad084757a049b7e5cdbadae5e9e400 from > November 2018. Unfortunately that's a pretty big squashed commit from > a PR: > https://github.com/urweb/urweb/commit/5cc729b48aad084757a049b7e5cdbadae5e9e400 > > It'd be great if someone could take a look and see why it strips UTF-8 > output in that benchmark test. Note that the test runs in a Docker > container, so perhaps it's trying to infer a system-wide i18n setting? > > Once we fix this, we can update the benchmarks repo and solve the > sorry state of affairs with Ur/Web way down the performance rankings. > I'd love to see more people active in the community, and things like > this would help raise awareness of the project. > > Oisín > I suspect this has to do with the difference between LTR and RTL languages. A given database, in the fortunes table, may have Arabic text stored "backwards", and without any markings such as U+200F RIGHT-TO-LEFT MARK and so the U8_NEXT macro is seeing a trailing byte of a UTF-8 encoded character and failing to loop. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
[Ur] The right way to do federated login in 2015?
I don't think it is in use today, but an idea for a federated login that does not reveal usage information to the authentication service is SPRESSO, described here: http://arxiv.org/pdf/1508.01719.pdf ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] rpc calls from signals?
I think the GUI library has something that might suit your case. The sourceL.ur and sourceL.urs listed here: http://hg.impredicative.com/gui/file/d32fb0f7b137 I think implement the change listener Adam mentioned. I was kind of expecting that, but I do think it is a common thing and so probably useful to support in some way (though probably best done somewhat separately). The main reason I wanted to have them connected is to re-use the runtime checks that are looking for changes - having a check running every N milliseconds seems really pointless when the javascript runtime already knows when values are changing. Would there be a way to set up an event listener for changes on a source? I can obviously create a changed source for each source I have, and then flip it on when the source changes, and off in the thread that is making rpc calls, but ideally that thread wouldn't even be woken up unless the change had happened. Though maybe I'm bean counting given how fast even phones are these days... (and indeed I'm only concerned about phones, and primarily for the sake of battery life, not responsiveness). On Mon, Mar 11, 2013 at 10:47 AM, Adam Chlipala ad...@csail.mit.edu wrote: On 03/11/2013 10:20 AM, Daniel Patterson wrote: Is there a way to call remote procedures in signal handlers? I looked through the manual and basis.urs and couldn't find anything. The use case isn't particularly strange: I want to persist client side changes on the server, ideally only making rpc calls when something actually changes. I can spawn a thread that checks periodically if the value has changed (that's what I ended up hacking together), but at that point I'm replicating imperatively what FRP is supposed to eliminate! I would actually consider it a bug if what you ask were possible! The [signal] monad is meant to rule out side effects, and RPCs can cause arbitrary side effects, not just locally but out in the real world. There would need to be some kind of type system, etc., to recognize RPCs that are suitably pure. Imagine the consequences of the launch missile RPC running every time the runtime system decides that some DOM subtree needs recomputation. ;) Why not implement a general library for change listeners? Certainly there is some duplication with FRP, but at the same time I would expect it's pretty straightforward to implement. You could create a new abstract type that encapsulates a [source] plus change listeners. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] The future of [class] declarations
Well, while Ur is full of undecidable type inference issues, I generally try to keep type _checking_ (of sufficiently annotated programs) decidable or at least predictable. It seems hard to support predictable checking of same-module type class usage without requiring restrictions that don't apply elsewhere. To explain: If picking up the instances must lead to undecidable type checking then removing the class declaration seems very good to me. Yet if the restrictions you mention could be mild while still leaving type checking decidable and allowing instance detection then maybe keeping the class declaration could be considered. What sort of restrictions would be required? When a type class is considered as an abstract type-level function, I believe it is decidable whether a particular type equals an application of the class. However, when inference must be done where a type class's definition is exposed, I _think_ the problem is clearly undecidable, being an easy reduction target for the problem of higher-order unification. So I guess a sufficient (but perhaps too onerous) restriction could be for the programmer to provide annotations showing which types are class applications? Also, now that you are a professor, maybe you could put a student to showing undecidability by working through your reduction! ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Request environment variables
Hello all, Servers pass a lot of interesting information to the CGI programs in the form of environment variables (for example, if you do client cert authentication, that info comes in the form of an environment variable.) It would be great if Ur/Web could access that information. Now, implementing this requires a little bit of cooperation from the SAPIs, since, for example, FastCGI passes in its environment variables from the wire, so just calling getenv doesn't work. But probably a 'getenv : string - transaction string' would work reasonably well. Thoughts? Maybe type env_var_name = string type env_var_content = string val getenv : transaction (list (env_var_name * env_var_content)) to receive the complete environment at once? ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] XHTML character entities
On Wednesday, November 16, 2011 08:10:57 AM Adam Chlipala wrote: James Parker wrote: Sorry for taking so long to get back to you. Yes, it now parses and compiles copy;. The only thing is Firefox 8 (OS X 10.7) adds an extra character before the copyright symbol. I have attached a screenshot. Weird. Works fine in Chrome and Opera. Right now, I'm compiling the character entities into normal UTF-8, but perhaps it's necessary to output them as character entities. I'll look into it soon. Thanks for the bug report! Attached patch including the character encoding with the response mime type seems to work for Firefox. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur# HG changeset patch # User Karn Kallio kkallio@eka # Date 1321467682 16200 # Node ID 3e24c24a25004b5f8d73ee964d8b815a675ba091 # Parent 7862f89674b909575a00c81c0d54a3acc367cafb Include character encoding in HTTP response headers. diff -r 7862f89674b9 -r 3e24c24a2500 src/cjr_print.sml --- a/src/cjr_print.sml Mon Nov 14 11:56:30 2011 -0430 +++ b/src/cjr_print.sml Wed Nov 16 13:51:22 2011 -0430 @@ -2814,7 +2814,7 @@ box (case ek of Core.Rpc _ = [string uw_write_header(ctx, \Content-type: text/plain\\r\\n\);, newline] -| _ = [string uw_write_header(ctx, \Content-type: text/html\\r\\n\);, +| _ = [string uw_write_header(ctx, \Content-type: text/html; charset=utf-8\\r\\n\);, newline, string uw_write_header(ctx, \Content-script-type: text/javascript\\r\\n\);, newline, ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Abstract type for 'id' attributes?
On Tuesday, August 30, 2011 06:45:10 PM Adam Chlipala wrote: Currently, Ur/Web supports an 'id' attribute on any XML element. I added this when someone requested support for the label tag. Currently, 'id' attributes have type [string]. This freaks me out somewhat, since it's anti-modular; different functions written by different people might need to coordinate to avoid duplicating IDs. The use of IDs is convenient for FFI JavaScript code that wants to get handles to DOM nodes. So, I'm thinking of adding an abstract type of IDs, with only one built-in operation: generate fresh ID. Every tag's 'id' attribute would change to take a value of this type. Under the hood, these would just be strings, making for easy FFI integration. Does anyone object to the idea? Any other feedback? No objection, I think it is a good idea. For integration with external CSS and FFI Ecmascript, would it be possible to have a second operation that takes a suggestion string and generates an id having that as the under the hood value if it is not already taken? Already taken suggestions then cause an error if given again, or alternatively are ignored or modified. Without some sort of mechanism for controlling or mapping id string values I think it will generally be impossible to use external resources (eg style sheets on another server or under control of some other team). ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] hiccups with tutorial ...
Hello ur group, I am running Linux Komputer 2.6.32-33-generic #70-Ubuntu SMP Thu Jul 7 21:09:46 UTC 2011 i686 GNU/Linux . I upgraded my system, e.g. sudo apt-get install postgresql. But got below . ?? With Debian/Ubuntu it may be necessary to install a package called postgresql- dev or similar. This is a guess, I do not in fact know if that is a solution. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Weird behavior with dyn tags in recursive call
I was trying to modify the tree example to be a collapsing tree and when this renders the javascript ends up getting spewed out all over the form. It looks like it's getting escaped or something. If I understand correctly, any dyn xml which must be spliced into the document at program execution time will be escaped ... only dyn tags which are spliced in at compile time will work. So any dyn tags whose inclusion depends on the execution environment (like in your case the database state) will be escaped. I don't think the difficulty is related to recursive calls. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] A direction for Ur/Web
Well, some similar fuzzy brainstorming that has occurred to me before: To have safely tweakable themes Ur/Web could represent them as types in some way. That probably means Ur/Web will have to represent CSS too. To naturally support user changes of themes at run time then probably implies that Ur/Web will need more support for dependent types, to allow expressions of a theme type depending on a value coming from a user. Why is linking to an alternate style sheet not enough to effect such a change? This is completely supported even in the most recent official Ur/Web release. I assume safely tweakable themes require some sort of guarantee that there is at least a minimum level of correspondence between the CSS and the XHTML. The current mechanism of linking to a style sheet provides no guarantees on the CSS content of that style sheet; indeed, the style sheet may not even contain valid CSS. Of course Ur/Web supports theming, but I don't think it currently supports *safe* theming. Control of CSS class attributes via style helps but leaves too much underspecified to be safe (in my opinion). If you want any more than this, then major changes to the language/compiler would be required, since the present support is based essentially on whole-program compilation. Yes, certainly, but I guess it could be a future direction for Ur/Web. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] A direction for Ur/Web
What about a wiki page ? SASS/HAML could be implemented as well. It looks like it doesn't make sense to implement all features of haml-lang.com. But most of its syntax is much nicer to write. I do not think that HAML or SASS add any abstractions that Ur/Web with a full CSS support would not already have. So in that sense implementing them would not gain anything. If Ur/Web gained a sort of a typed macro system allowing user level implementation of SASS/HAML as a syntactic DSL that would be really interesting. Why would a macro system be needed? You can get a long way with string parsing. See, for example, this HTML parser: http://hg.impredicative.com/meta/file/d05943db55e8/html.urs Some sort of multistaging mechanism (right, not macros) would be needed to allow programmers to prepare type safe source code containing Sass and Haml syntax. Runtime parsers are perfect for supporting things like BBcode in forums. I was conjuring up some imaginary facility for programmers to define their own DSL/syntax that would elaborate into well typed Ur/Web or something. I realize this would be a research campaign ... take it in the spirit of wildly suggesting a possible far far future direction for Ur/Web. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] A direction for Ur/Web
What about a wiki page ? SASS/HAML could be implemented as well. It looks like it doesn't make sense to implement all features of haml-lang.com. But most of its syntax is much nicer to write. I do not think that HAML or SASS add any abstractions that Ur/Web with a full CSS support would not already have. So in that sense implementing them would not gain anything. If Ur/Web gained a sort of a typed macro system allowing user level implementation of SASS/HAML as a syntactic DSL that would be really interesting. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] demo isn't working
hi all, yesterday i was trying the demo one by one, suddenly the server was down and is still unavailable. Is it my network problem or we all experience this? -- Best Regards， Liu Qiang It seems to be the server ... the demos show me this: Service Temporarily Unavailable The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later. The additional demos ( http://www.impredicative.com/ur/more/ ) and the UrFlow demo ( http://www.impredicative.com/ur/scdv/ ) are still available though. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
[Ur] Compiler Bug?
Here is an example of Ur/Web code which leads to generation of a webapp.c
which does not compile ... maybe it is an urweb compiler bug?
Title: Example
example.urp
-
$/list
example
example.urs
-
val main : unit -> transaction page
example.ur
-
val intList = 1 :: 2 :: 3 :: []
val intListList = intList :: intList :: []
fun main () = return
Example
{[intListList]}
urweb.stderr
-
/nix/store/bdh974nds32c3rsdvan961ll7bhn9fi9-lkl-urweb/lib/urweb/ur/list.ur:3:23-3:29: Function type remains
/nix/store/bdh974nds32c3rsdvan961ll7bhn9fi9-lkl-urweb/lib/urweb/ur/list.ur:3:23-3:29: Function type remains
/tmp/filePZce0S/webapp.c:38:4: error: expected declaration specifiers or ‘...’ before ‘<’ token
/tmp/filePZce0S/webapp.c:40:50: error: expected declaration specifiers or ‘...’ before ‘<’ token
cc1: warnings being treated as errors
/tmp/filePZce0S/webapp.c: In function ‘__uwn_$showPRIME_unpoly_1275’:
/tmp/filePZce0S/webapp.c:74:15: error: implicit declaration of function ‘__uwr_$x_0’
/tmp/filePZce0S/webapp.c:76:39: error: passing argument 2 of ‘__uwn_$showPRIME_unpoly_1275’ from incompatible pointer type
/tmp/filePZce0S/webapp.c:40:5: note: expected ‘struct __uws_2 *’ but argument is of type ‘int (*)()’
/tmp/filePZce0S/webapp.c:76:39: error: too many arguments to function ‘__uwn_$showPRIME_unpoly_1275’
/tmp/filePZce0S/webapp.c:40:5: note: declared here
/tmp/filePZce0S/webapp.c: In function ‘__uwn_wrap_main_1274’:
/tmp/filePZce0S/webapp.c:240:51: error: passing argument 2 of ‘__uwn_$showPRIME_unpoly_1275’ from incompatible pointer type
/tmp/filePZce0S/webapp.c:40:5: note: expected ‘struct __uws_2 *’ but argument is of type ‘char * (*)(struct uw_context *, struct __uws_1 *)’
/tmp/filePZce0S/webapp.c:240:51: error: too many arguments to function ‘__uwn_$showPRIME_unpoly_1275’
/tmp/filePZce0S/webapp.c:40:5: note: declared here
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Re: [Ur] sanity checking
Karn Kallio wrote: Well, looking at the code I thought that it should output both, because gcc is supposed to support non-constant initializers. But I am not really any help, because I do not know enough about gcc to say. One thing that I do notice in your example is that the printf should be leaving an integer in the __uwf_1 position of tmp but how could there be space for it (as uw_unit should occupy 0 size) ... I think this is a confusion between the comma separator between initializer elements and the comma operator in expressions. I think my use of parentheses triggers interpretation as the latter, not the former. You are right of course ... I did think it was two initializer elements, but now I see that your example initializes the first leaving the second to default ... ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Using Ur/Web to create standalone JS applications
Vag Vagoff wrote: On 12.12.2010 18:06, Marc Weber wrote: Which kind of application do you have in mind where this really matters? Maybe we can help you find an alternative (Eg Amazon cloud like stuff) You are not specific enough. Which web application do you have in mind? Various small sites like business cards, web shops and forums. My suggestion is that, if Ur/Web still sounds promising to you from a purely technical standpoint, spend some time making sure it's really the right language for you. Just like its main influences ML and Haskell, it probably isn't appropriate for most programmers. If you still like it and lack of super-cheap hosting services is an issue, we may be able to work out some VPS sharing on this list. I wouldn't necessarily be against subsidizing a big chunk of the cost, if the language, tools, and community are being advanced. Has graftid been closed down for good? The http://www.graftid.com/ does not respond. I believe Graftid was intended to be something like a community arena for Ur/Web development, no? ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
[Ur] sanity checking
Same here with gcc (GCC) 4.4.3 [kkal...@eka:~/scratch/test]$ gcc test.c [kkal...@eka:~/scratch/test]$ ./a.out Outer ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] sanity checking
Karn Kallio wrote: Same here with gcc (GCC) 4.4.3 [kkal...@eka:~/scratch/test]$ gcc test.c [kkal...@eka:~/scratch/test]$ ./a.out Outer Thanks. The other important question is whether, when you look at the code, you also expect it to output two lines, not just one. Well, looking at the code I thought that it should output both, because gcc is supposed to support non-constant initializers. But I am not really any help, because I do not know enough about gcc to say. One thing that I do notice in your example is that the printf should be leaving an integer in the __uwf_1 position of tmp but how could there be space for it (as uw_unit should occupy 0 size) ... ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Documentation codes
Hey folks, I've taken a look at the Ur/Web demos the other day and read a couple emails on the list. if anyone's worried about Ur/Web surviving or gaining wide-spread adoption, well, just fill in as much info/examples on the Wiki as you can, and add any usable code you might have, or link to your projects. For example, I'd be very interested in seeing what Marc did with the Ruby connector. Cya, Davor Good idea! Since I was quite confused about folders a couple of days ago ( until Adam pointed out the problem .. thanks! ) I put a sample of usage of fold on the Wiki. http://www.impredicative.com/wiki/index.php/Using_Top.Fold_to_count_fields_of_a_record ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
[Ur] Record subtype constraint
I thought to express record subtyping using Ur/Web's disjointness constraints
and symmetric concatenation.
This works:
fun subrecord [super :: {Type}] [evidence ::: {Type}] [super ~ evidence] (sub
: $(super ++ evidence)) = sub
con supertype :: {Type} = [One = string, Two = string]
val subrec = subrecord [supertype] {One = foo, Two = bar, Three = baz}
(* ok, doesn't compile *)
val subrec' = subrecord [supertype] {One = foo, Three = baz}
The Ur/Web compiler automatically finds the evidence showing the value
argument has a record subtype or gives a compile error if it is not a subtype.
But I thought a better way to witness that a given record is a subtype would
be to return the portion with the supertype, so we can use the result in
contexts expecting the supertype.
However, this does not compile:
fun subrecord' [super :: {Type}] [extension ::: {Type}] [super ~ extension]
(fl : folder super) (sub : $(super ++ extension))
= fl [fn (r :: {Type}) = ($(super ++ extension) - $r)]
(fn [nm :: Name] [t :: Type] [r :: {Type}] [[nm] ~ r] acc src = {nm =
sub.nm} ++ acc (src))
(fn _ = {}) sub
val subrec' = subrecord' [supertype] {One = foo, Two = bar, Three = baz}
giving error:
f.ur:11:4-11:6: Expression is not a constructor function
Expression: fl
Type: Top.folder[[Type]] super
f.ur:15:26-15:35: Substitution in constructor is blocked by a too-deep
unification variable
Replacement: [#One = string, #Two = string]
Body:
extension ::: {Type} -
[UNBOUND_REL1 ~ extension] =
((Top.folder[[Type]] UNBOUND_REL1) -
($(UNBOUND_REL1 ++ extension) - UNIF:F::Type))
which looks like the unification does not get into the [fn (r :: {Type}) =
($(super ++ extension) - $r)] parameter to fl.
What is happening? Is the compile error due to incompleteness in the
unification implementation ( related to folder inference maybe? ) or have I
written nonsense ( and the compiler of course rejects it )?
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Re: [Ur] Record subtype constraint
Karn Kallio wrote: However, this does not compile: [codesnip] giving error: f.ur:11:4-11:6: Expression is not a constructor function Expression: fl Type: Top.folder[[Type]] super This makes sense, since you are trying to apply [fl] as a constructor function, but it isn't one, it's a [folder]. [folder] is an abstract type family. You should instead be calling [Top.fold], which can be abbreviated to just [fold]. Aha! Thanks! In case anyone else wonders how to express record subtype constraints I posted a page on the wiki : http://www.impredicative.com/wiki/index.php/Expressing_subrecord_constraints ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Strategy - UrWeb Backend
Excerpts from Adam Chlipala's message of Wed Dec 08 00:40:43 +0100 2010: Which benefits do you see from server-side JavaScript? I'll be really surprised if any such system can get over the inherent costs of the JavaScript language, to match the performance and security of Ur/Web. Performance does no longer matter much (unless you're Amazon - or google) - because servers are so cheap compared to development time - and they will be even cheaper tomorrow. This has been true for the last few decades, but the age of hardware improvements may be almost over. Clock frequency has stopped increasing since about 5 years, limited by heat dissipation I believe. Shrinking die feature sizes to even a couple of nanometers gives only about a 100x increase in transistor density. So the industry may be approaching physical limits within the next 5 to 10 years that will stall hardware improvements. Then at the end of the hardware era the only way forward will be software. Disclaimer: I am not knowledgeable about hardware and of course I can't know the future ... only that maybe the inevitable end (physics limits trivially mean there has to be an end) of cheaper tomorrow might not be so far ahead Benefits of JS target: - never think about memory - interface to existing code more easily (?) - existing hosting services (heroku) You already said that you don't want to target the masses. Having some more users helping testing would be fine though :) Writing tutorials is probably more important right now than having NodeJS support. If there are enough skilled users someone will pick it up and implement it anyway (?) Marc Weber ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Generalizing transactions
Karn Kallio wrote: Adam, now that somebody ( Marc Weber ) is working on an application ( payment gateway ) where the transaction model of Ur/Web does not cleanly apply, is there a chance of you generalizing Ur/Web transactions in a safe, principled way ( that allows representing the semantics of the application's effectful operations within Ur/Web )? For example, I think that the problem of leaving a permanent record of an event ( e.g. receiving an order and not removing it on failure rollback ) could be handled with a SAGA that has a null compensation for the process of writing the record. It seems like Marc and I have settled on a very straightforward and not-ugly way of implementing what he wants, so this case doesn't seem to me like a good impetus to add a new fancy feature. I'm perfectly happy to help you figure out how to implement it yourself, if you want. :-) Ok :) Please accept my apologies for sounding snarky or demanding. I want to be clear that I think Ur/Web is an amazing accomplishment and that you are breaking important new ground in the design space for the coming generation of almost dependently typed languages. Also, about impredicative kind polymorphism, I was not complaining, only trying to make a joke ... I think that for the intended domain the existing implementation of kind unification is fine. To illustrate that Ur/Web *does* exhibit impredicativity at the value/type level ( you have already pointed this out, but just to undo any confusion I may have left on this list ) I posted an example on the wiki at http://www.impredicative.com/wiki/index.php/Impredicativity_in_Ur/Web Once again, thanks for Ur/Web ! ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Generalizing transactions
Excerpts from Karn Kallio's message of Tue Nov 30 16:24:43 +0100 2010: Adam, now that somebody ( Marc Weber ) is working on an application ( payment gateway ) where the transaction model of Ur/Web does not cleanly apply, is there a chance of you generalizing Ur/Web transactions in a safe, principled way ( that allows representing the semantics of the application's effectful operations within Ur/Web )? For example, I think that the problem of leaving a permanent record of an event ( e.g. receiving an order and not removing it on failure rollback ) could be handled with a SAGA that has a null compensation for the process of writing the record. Karn Kallio: I don't know yet whether I'm going to implement them all - or writing some interfaces to reuse existing code. SAGA? Wikipedia is refering to: * SAGA (computing), a Simple API for Grid Applications * SAGA GIS, a geographic information system Do you talk about any of these two? I meant these : http://lanl.arxiv.org/abs/1010.5569 The manual says: context is the type of state that persists across handling a client request So it looks like I can use uw_(set,get)_global and uw_malloc to keep caches. I can use the uw_set_global rollback / commit handler to set a flag to succeeded or failed in the data structure. I know that the free handler will be called after the request finished (giving up (fatal error) or suceeding). The flag will tell me whether I have to trace a failure in a logfile. Do you want users to print to stderr for logging - or do you want to introduce a logging function which also adds time stamps etc? (good idea IMHO) - Does it already exist? Marc Weber ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
[Ur] [PATCH] Static link to libmhash when -static parameter given
The Ur/Web compiler links to the libmhash dynamic library independent of the
-static parameter being given to the compiler, which links only the liburweb
statically.
This patch makes the Ur/Web compiler also link libmhash statically with the -
static flag. The motivation is to have -static produce programs which can run
on machines without a special Ur/Web installation ( considering libmhash as
part of a Ur/Web installation because it is not likely to be found on many
machines ).
The goal is to use -static to produce executables which can be placed on
shared hosting Linux servers with Apache CGI via FTP ... bringing Ur to the
world
The patch adds a configure flag --with-mhash-dir to let the Ur/Web compiler
know how to find libmhash.a in order to pass it along to gcc.
I do not know if this patch will interact badly with the FFI mechanism of
Ur/Web.
Note: after applying the patch I did $autoreconf -i to update the autotools
build system.
diff -r df7bfb30dcc3 configure.ac
--- a/configure.ac Sat Nov 13 14:38:06 2010 -0500
+++ b/configure.ac Mon Nov 15 20:04:17 2010 -0430
@@ -6,8 +6,20 @@
AC_CONFIG_MACRO_DIR([m4])
AC_CONFIG_HEADERS([config.h])
-AC_CHECK_LIB(mhash, mhash_get_block_size, [], [echo You must install libmhash.; exit 1])
-AC_CHECK_HEADER([mhash.h], [], [echo You must install libmhash dev files.; exit 1])
+dnl Setting the search directory for mhash.
+AC_ARG_WITH(mhash-dir, AS_HELP_STRING([--with-mhash-dir=DIR], [mhash directory; default = /usr]),
+ with_mhash_dir=$withval, with_mhash_dir=/usr)
+
+dnl Check for libmhash
+LIBS_save=$LIBS
+LIBS=-L${with_mhash_dir}/lib/ -lmhash
+AC_CHECK_LIB(mhash, mhash_get_block_size,
+[MHASH_LIB_DIR=${with_mhash_dir}/lib], [echo You must install libmhash.; exit 1])
+LIBS=${LIBS_save}
+
+dnl Check for mhash.h
+AC_CHECK_HEADER([${with_mhash_dir}/include/mhash.h],
+[CPPFLAGS=${CPPFLAGS} -I${with_mhash_dir}/include], [echo You must install libmhash dev files.; exit 1])
AC_CHECK_PROG(MLTON, mlton, yes, [])
@@ -55,6 +67,7 @@
AC_SUBST(INCLUDE)
AC_SUBST(SITELISP)
AC_SUBST(GCCARGS)
+AC_SUBST(MHASH_LIB_DIR)
AC_CONFIG_FILES([
Makefile
@@ -67,9 +80,10 @@
cat EOF
Ur/Web configuration:
- bin directory: BIN $BIN
- lib directory: LIB $LIB
- include directory: INCLUDE $INCLUDE
- site-lisp directory: SITELISP $SITELISP
- Extra GCC args: GCCARGS $GCCARGS
+ bin directory: BIN$BIN
+ lib directory: LIB$LIB
+ include directory: INCLUDE$INCLUDE
+ site-lisp directory: SITELISP $SITELISP
+ mhash lib directory: MHASH_LIB_DIR $MHASH_LIB_DIR
+ Extra GCC args: GCCARGS$GCCARGS
EOF
diff -r df7bfb30dcc3 src/compiler.sml
--- a/src/compiler.sml Sat Nov 13 14:38:06 2010 -0500
+++ b/src/compiler.sml Mon Nov 15 20:04:17 2010 -0430
@@ -1225,16 +1225,16 @@
let
val proto = Settings.currentProtocol ()
-val lib = if Settings.getStaticLinking () then
- #linkStatic proto ^ ^ Config.lib ^ /../liburweb.a
- else
- -L ^ Config.lib ^ /.. -lurweb ^ #linkDynamic proto
-
+val (lib, mhash) = if Settings.getStaticLinking () then
+ (#linkStatic proto ^ ^ Config.lib ^ /../liburweb.a, Config.libMhash ^ /libmhash.a)
+ else
+ (-L ^ Config.lib ^ /.. -lurweb ^ #linkDynamic proto, -L ^ Config.libMhash ^ -lmhash)
+
val compile = gcc ^ Config.gccArgs ^ -Wimplicit -Werror -O3 -fno-inline -I ^ Config.includ
^ ^ #compile proto
^ -c ^ cname ^ -o ^ oname
-val link = gcc -Werror -O3 -lm -lmhash -pthread ^ Config.gccArgs ^ ^ libs ^ ^ lib ^ ^ oname
+val link = gcc -Werror -O3 -lm -pthread ^ Config.gccArgs ^ ^ libs ^ ^ lib ^ ^ mhash ^ ^ oname
^ -o ^ ename
val (compile, link) =
diff -r df7bfb30dcc3 src/config.sig
--- a/src/config.sig Sat Nov 13 14:38:06 2010 -0500
+++ b/src/config.sig Mon Nov 15 20:04:17 2010 -0430
@@ -9,4 +9,5 @@
val libJs : string
val gccArgs : string
+val libMhash : string
end
diff -r df7bfb30dcc3 src/config.sml.in
--- a/src/config.sml.in Sat Nov 13 14:38:06 2010 -0500
+++ b/src/config.sml.in Mon Nov 15 20:04:17 2010 -0430
@@ -14,4 +14,6 @@
val gccArgs = @GCCARGS@
+val libMhash = @MHASH_LIB_DIR@
+
end
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Re: [Ur] new user having some questions such as a:::Type twice? and more
With regards to 8) there is a mercurial repository available; hg clone http://hg.impredicative.com/urweb should get you a copy. ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
Re: [Ur] Exceptions handling
Vladimir Shabanov wrote: So savepoint will be introduced only where it really needed (dml with user error handling)? I think that this is the best solution. Yes, that's what I meant. BTW it can be useful to have function for cancelling (and maybe restarting) transaction as a part of error handling. In Ur/Web, transactions are used for all state, not just the database. I would want to have a reasonable integration of transaction restart with all kinds of state, which can include arbitrary protocols thanks to C FFI libraries. That would complicate the FFI, so I'll leave this out for now. If a compelling use case comes up, let me know. In PostgreSQL, use of the Serializable transaction isolation level will give failures whenever for example a transaction selects a set of rows and another concurrent transaction modifies some before the query finishes. These serialization failure errors generally need the application to cancel and retry the transaction. So I suppose with PostgreSQL, a use case could be any situation where Serializable isolation levels are called for. Transactions that include a mixture of complicated selects and updates will probably need the Serializable isolation level. An example could be some sort of reporting application where presentation tables are filled with results computed from input tables via multiple steps with several layers of tables holding intermediate results. If many users are concurrently adding data to the input tables and viewing the presentation tables Serializable would probably be necessary. Whenever two users input data that resulted in overlapping changes in an intermediate result table cancel/retry would have to be done. Reference: http://www.postgresql.org/docs/8.4/static/transaction-iso.html Section 13.2.2 ___ Ur mailing list Ur@impredicative.com http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
[Ur] Ur/Web in Nixos
Maybe of interest:
While packaging Ur/Web for NixOS ( http://nixos.org/ , a Linux distribution
using a non-standard prefix-based directory layout ) it was necessary to apply
a patch removing the postgresql directory prefix hardcoded in the header paths
in the file postgres.sml.
I believe using GCCARGS to pass include directory locations via -I can't be
made to work without introducing symlinks or some such whenever the actual
header files mysql.h and libpq-fe.h are contained in directories not named
postgresql and mysql.
Removing the prefixes allows GCCARGS to determine the location; I imagine it
will also make the build fail on standard filesystem layouts without some more
autotools tweaking.
Anyway, here is the patch removing the prefix directories.
diff -Naur urweb-orig/src/mysql.sml urweb-patched/src/mysql.sml
--- urweb-orig/src/mysql.sml 2010-08-23 15:36:58.665234434 -0430
+++ urweb-patched/src/mysql.sml 2010-08-23 15:44:10.765238334 -0430
@@ -1521,7 +1521,7 @@
fun p_blank _ = ?
val () = addDbms {name = mysql,
- header = mysql/mysql.h,
+ header = mysql.h,
link = -lmysqlclient,
init = init,
p_sql_type = p_sql_type,
diff -Naur urweb-orig/src/postgres.sml urweb-patched/src/postgres.sml
--- urweb-orig/src/postgres.sml 2010-08-23 15:36:58.666253464 -0430
+++ urweb-patched/src/postgres.sml 2010-08-23 15:43:26.216251221 -0430
@@ -928,7 +928,7 @@
fun p_blank (n, t) = p_cast ($ ^ Int.toString n, t)
val () = addDbms {name = postgres,
- header = postgresql/libpq-fe.h,
+ header = libpq-fe.h,
link = -lpq,
p_sql_type = p_sql_type,
init = init,
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