However, besides state synchronization is under development, state persistence in MFlow is optional, by using the workflow monad instead of the IO monad. See for example this:
http://mflowdemo.herokuapp.com/shop 2013/7/10 Alberto G. Corona <agocor...@gmail.com> > My plan is to synchronize MFlow servers using cloud Haskell since the > state serialization is small. I´m working on it. However continuation > based frameworks can not synchronize state. There is "swarm" in scala that > generate portable continuations but this is not used in the context of web > application since the state in a continuation is big and can not be > synchronized fast enough. In other languages these states are not even > portable between machines. > > > 2013/7/10 Alexander Kjeldaas <alexander.kjeld...@gmail.com> > >> Here are some common-lisp web frameworks using continuations: >> >> http://common-lisp.net/project/cl-weblocks/ >> http://common-lisp.net/project/ucw/features.html >> >> What always worried me with these frameworks is how they could be made >> robust in case of failures. Storing all state in a database backend often >> makes it possible to isolate failures. However, it seems to me that it is >> be possible to solve this in Haskell where state can be serialized and >> synchronized between multiple machines using Cloud Haskell, something that >> is error-prone or impossible in other languages. But that step has never >> been taken. >> >> Alexander >> >> >> On Wed, Jul 10, 2013 at 4:48 PM, Alberto G. Corona >> <agocor...@gmail.com>wrote: >> >>> Thanks Adrian. The racket people where pioneers in this idea I think. >>> >>> There is another web framework in Ocaml, Osigen that it is also >>> continuation based. MFlow is not continuation-based but it also define the >>> navigation as a sequence. But only Seaside (and now MFlow) supports many >>> flows in the same page. See for example this: >>> >>> [PDF] *Seaside* – A *Multiple* Control *Flow* Web Application >>> Framework<http://www.google.es/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=3&cad=rja&ved=0CEwQFjAC&url=http%3A%2F%2Fscg.unibe.ch%2Farchive%2Fpapers%2FDuca04eSeaside.pdf&ei=WnPdUYHPI-Ly7Aaa0oHQDA&usg=AFQjCNFxwsFQc9QsQCNPRFfD4t6ReQtP5g&sig2=_klwtzxIKW5UzAOUDOvFCw> >>> >>> There is also other: Apache Coccoon that run in a special kind of >>> JavaScript. The continuation-based frameworks have the reputation of >>> storing a lot of application state and to be non scalable. MFlow >>> uses backtracking and It does not have these problems. >>> >>> >>> 2013/7/10 Adrian May <adrian.alexander....@gmail.com> >>> >>>> Oh how nice! >>>> >>>> I have been looking at MFlow a lot lately and I think it's got >>>> something quite special that Yesod, Happstack, etc don't seem to have, at >>>> least, not as far as I know. I mean, look at this: >>>> >>>> sumWidget= pageFlow "sum" $ do >>>> >>>> n1 <- p << "Enter first number" ++> getInt Nothing <** submitButton >>>> "enter" <++ br >>>> >>>> >>>> >>>> >>>> >>>> >>>> n2 <- p << "Enter second number" ++> getInt Nothing <** submitButton >>>> "enter" <++ br >>>> >>>> >>>> >>>> >>>> >>>> >>>> n3 <- p << "Enter third number" ++> getInt Nothing <** submitButton >>>> "enter" <++ br >>>> >>>> >>>> >>>> >>>> >>>> >>>> p << ("The result is: "++show (n1 + n2 + n3)) ++> wlink () << b >>>> << " menu" >>>> >>>> >>>> >>>> >>>> >>>> >>>> <++ p << "you can change the numbers in the boxes to see how the >>>> result changes" >>>> >>>> Is that pretty or what? That's the code for this: >>>> >>>> http://mflowdemo.herokuapp.com/noscript/fviewmonad >>>> >>>> To me that's a real technological step over and above the usual >>>> servlets paradigm and I'd love to see more people getting involved. It >>>> seems like Yesod and Happstack have a lot more manpower behind them, but >>>> unless I've missed something, MFlow is going somewhere new and should be >>>> helped along. >>>> >>>> Adrian. >>>> >>>> PS. Besides Seaside, Racket is playing with the same ideas. They (Jay >>>> McCarthy) have something to say about performance but I didn't quite >>>> understand it. >>>> >>>> >>>> >>>> On 10 July 2013 06:41, Alberto G. Corona <agocor...@gmail.com> wrote: >>>> >>>>> The third version of MFlow is out. >>>>> >>>>> http://hackage.haskell.org/package/MFlow >>>>> >>>>> MFlow is an all-heterodox web application framework, but very >>>>> haskellish. >>>>> >>>>> Now MFlow support restful URLs. It is the first stateful web >>>>> framework to my knowledge that supports it. The type safe routes are >>>>> implicitly expressed as normal monadic code within a navigation monad. The >>>>> application look as a normal imperative console application, but the >>>>> navigation monad goes back and forth to match the path of the URL. The >>>>> user >>>>> has control of the state, that can roll-back or not when the navigation >>>>> goes back depending on the application needs. The state is in the form of >>>>> normal Haskell variables In a monadic computation, with the weird addition >>>>> of backtracking. >>>>> >>>>> The menu of the application below is implemented as an imperative-like >>>>> syntax, but the application navigate forward and backward to synchronize >>>>> with the requests of the web browser: >>>>> http://mflowdemo.herokuapp.com/ >>>>> >>>>> This version support in-page flows. >>>>> What is that? look at this example: >>>>> >>>>> http://mflowdemo.herokuapp.com/noscript/fviewmonad >>>>> >>>>> These flows are implemented as formlets with a monad instance, and >>>>> callbacks which change the look. I call them "widgets": >>>>> >>>>> >>>>> http://haskell-web.blogspot.com.es/2013/06/the-promising-land-of-monadic-formlets.html >>>>> >>>>> >>>>> Each page may have many of these active widgets, each one running >>>>> their own flow. These widgets refresh themselves trough Ajax if they are >>>>> enclosed in the primitive "autoRefresh". If there is no Ajax or JavaScript >>>>> available, they gracefully degrade by refreshing the entire page: >>>>> >>>>> http://mflowdemo.herokuapp.com/noscript/combination >>>>> >>>>> >>>>> http://haskell-web.blogspot.com.es/2013/06/and-finally-widget-auto-refreshing.html >>>>> >>>>> The page flows and the multiflow idea was inspired in >>>>> Seaside<http://www.seaside.st/>, >>>>> a great Smalltalk web framework and adapted to the pure recursive nature >>>>> of >>>>> Haskell and the formlets. >>>>> >>>>> It also support some JQuery widgets integrated: modal and not modal >>>>> dialogs, datePicker and other active widgets that handle other widgets. >>>>> >>>>> It also support the older features: persistent state, WAI, blaze-html >>>>> and others integration, server process timeouts, Ajax, requirements, >>>>> content management, caching of widget rendering and all the other >>>>> previous stuff. >>>>> >>>>> I wish to thank some people for their feedback. Specially Adrian May >>>>> for his feedback and interest >>>>> >>>>> >>>>> -- >>>>> Alberto. >>>>> >>>>> _______________________________________________ >>>>> Haskell-Cafe mailing list >>>>> Haskell-Cafe@haskell.org >>>>> http://www.haskell.org/mailman/listinfo/haskell-cafe >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> Haskell-Cafe mailing list >>>> Haskell-Cafe@haskell.org >>>> http://www.haskell.org/mailman/listinfo/haskell-cafe >>>> >>>> >>> >>> >>> -- >>> Alberto. >>> >>> _______________________________________________ >>> Haskell-Cafe mailing list >>> Haskell-Cafe@haskell.org >>> http://www.haskell.org/mailman/listinfo/haskell-cafe >>> >>> >> > > > -- > Alberto. > -- Alberto.
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