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• Traversing tree and stopping halfway in Haskell

  - by Michael War

  I want to traverse a tree and return changes to the tree whilst doing so. The result should be a Maybe monad, with Just tree if it succeeds otherwise None. The question is, what is the cleanest way to stop with the traversing half-way and return None if necessary?

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• What's the "|" for in a Haskell class definition?

  - by martingw

  I can't figure out what the "| m - w"-part means in a class definition like this: class (Monoid w, Monad m) = MonadWriter w m | m - w What additional information does this add to the class definition?

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• Newbie: understanding main and IO()

  - by user1640285

  While learning Haskell I am wondering when an IO action will be performed. In several places I found descriptions like this: "What’s special about I/O actions is that if they fall into the main function, they are performed." But in the following example, 'greet' never returns and therefore nothing should be printed. import Control.Monad main = greet greet = forever $ putStrLn "Hello World!" Or maybe I should ask: what does it mean to "fall into the main function"?

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• Downloading movies with Bit torrent

  - by Quintin Par

  I come from a part of the world where the average Hollywood movie is released a year + later than in US. For example: Transformers: Revenge of the Fallen will be released only 5-6 months down the lane. The Reader, I think will not be released at all. Is this a right justification for me to download movies from the torrent networks and watch them? Even if I don’t share it? P.S I don’t think my country has all these American type cyber laws to catch me. It’s just the guilt feeling. Note: SuperUser is not a legal resource.

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• Laptop power supplies, does current matter?

  - by CodeSlave

  I have two laptops (same manufacture), with the same type of power connector. However, the power supplies/transformers are slightly different. The output on the first laptop's power supply is 15.6 V at 8.0 A. The output on the second laptop's power supply is 15.6 V at 5A. Clearly the voltages are the same, but the currents are different. I assume the second laptop's power supply can not be used on the first, because it can't supply enough power to the laptop. However, can the first laptop's power supply be safely used on the second laptop?

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• How to select chosen columns from two different entities into one DTO using NHibernate?

  - by Pawel Krakowiak

  I have two classes (just recreating the problem): public class User { public virtual int Id { get; set; } public virtual string FirstName { get; set; } public virtual string LastName { get; set; } public virtual IList<OrgUnitMembership> OrgUnitMemberships { get; set; } } public class OrgUnitMembership { public virtual int UserId { get; set; } public virtual int OrgUnitId { get; set; } public virtual DateTime JoinDate { get; set; } public virtual DateTime LeaveDate { get; set; } } There's a Fluent NHibernate map for both, of course: public class UserMapping : ClassMap<User> { public UserMapping() { Table("Users"); Id(e => e.Id).GeneratedBy.Identity(); Map(e => e.FirstName); Map(e => e.LastName); HasMany(x => x.OrgUnitMemberships) .KeyColumn(TypeReflector<OrgUnitMembership> .GetPropertyName(p => p.UserId))).ReadOnly().Inverse(); } } public class OrgUnitMembershipMapping : ClassMap<OrgUnitMembership> { public OrgUnitMembershipMapping() { Table("OrgUnitMembership"); CompositeId() .KeyProperty(x=>x.UserId) .KeyProperty(x=>x.OrgUnitId); Map(x => x.JoinDate); Map(x => x.LeaveDate); References(oum => oum.OrgUnit) .Column(TypeReflector<OrgUnitMembership> .GetPropertyName(oum => oum.OrgUnitId)).ReadOnly(); References(oum => oum.User) .Column(TypeReflector<OrgUnitMembership> .GetPropertyName(oum => oum.UserId)).ReadOnly(); } } What I want to do is to retrieve some users based on criteria, but I would like to combine all columns from the Users table with some columns from the OrgUnitMemberships table, analogous to a SQL query: select u.*, m.JoinDate, m.LeaveDate from Users u inner join OrgUnitMemberships m on u.Id = m.UserId where m.OrgUnitId = :ouid I am totally lost, I tried many different options. Using a plain SQL query almost works, but because there are some nullable enums in the User class AliasToBean fails to transform, otherwise wrapping a SQL query would work like this: return Session .CreateSQLQuery(sql) .SetParameter("ouid", orgUnitId) .SetResultTransformer(Transformers.AliasToBean<UserDTO>()) .List<UserDTO>() I tried the code below as a test (a few different variants), but I'm not sure what I'm doing. It works partially, I get instances of UserDTO back, the properties coming from OrgUnitMembership (dates) are filled, but all properties from User are null: User user = null; OrgUnitMembership membership = null; UserDTO dto = null; var users = Session.QueryOver(() => user) .SelectList(list => list .Select(() => user.Id) .Select(() => user.FirstName) .Select(() => user.LastName)) .JoinAlias(u => u.OrgUnitMemberships, () => membership) //.JoinQueryOver<OrgUnitMembership>(u => u.OrgUnitMemberships) .SelectList(list => list .Select(() => membership.JoinDate).WithAlias(() => dto.JoinDate) .Select(() => membership.LeaveDate).WithAlias(() => dto.LeaveDate)) .TransformUsing(Transformers.AliasToBean<UserDTO>()) .List<UserDTO>();

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• Stop Believing TV’s Lies: The Real Truth About "Enhancing" Images

  - by Eric Z Goodnight

  You’ve seen it over and over. The FBI uses their advanced technology to “enhance” a blurry image, and find a villain’s face in the worst possible footage. Well, How-To Geek is calling their bluff. Read on to see why. It’s one of the most common tropes in television and movies, but is there any possibility a government agency could really have the technology to find faces where there are only blurry pixels? We’ll make the argument that not only is it impossible with current technology, but it is very unlikely to ever be a technology we’ll ever see. Stick around to see us put this trope under the lenses of science and technology, and prove it wrong once and for all Latest Features How-To Geek ETC Stop Believing TV’s Lies: The Real Truth About "Enhancing" Images The How-To Geek Valentine’s Day Gift Guide Inspire Geek Love with These Hilarious Geek Valentines RGB? CMYK? Alpha? What Are Image Channels and What Do They Mean? How to Recover that Photo, Picture or File You Deleted Accidentally How To Colorize Black and White Vintage Photographs in Photoshop A History of Vintage Transformers: Decepticons Edition [Infographic] How to Determine What Kind of Comment to Leave on Facebook [Humorous Flow Chart] View the Cars of Tomorrow Through the Eyes of the Past [Historical Video] Add Romance to Your Desktop with These Two Valentine’s Day Themes for Windows 7 Gmail’s Priority Inbox Now Available for Mobile Web Browsers Touchpad Blocker Locks Down Your Touchpad While Typing

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• The How-To Geek Valentine’s Day Gift Guide

  - by Jason Fitzpatrick

  Valentine’s Day is less than week away; if you want to prove yourself the geekiest cupid around you’ll definitely want to check out our guide to geeky Valentine’s big and small. The following gift guide includes gifts for the geeks in your life and gifts for geeks to give those that appreciate their geeky nature. Our methodology for picking Valentine’s-related gifts focused on gifts that were either traditional Valentine’s day gifts with a geek-slant or a nod to an aspect of geek culture. Read on to check out the geektacular pickings we mined the internet to unearth. Latest Features How-To Geek ETC The How-To Geek Valentine’s Day Gift Guide Inspire Geek Love with These Hilarious Geek Valentines RGB? CMYK? Alpha? What Are Image Channels and What Do They Mean? How to Recover that Photo, Picture or File You Deleted Accidentally How To Colorize Black and White Vintage Photographs in Photoshop How To Get SSH Command-Line Access to Windows 7 Using Cygwin View the Cars of Tomorrow Through the Eyes of the Past [Historical Video] Add Romance to Your Desktop with These Two Valentine’s Day Themes for Windows 7 Gmail’s Priority Inbox Now Available for Mobile Web Browsers Touchpad Blocker Locks Down Your Touchpad While Typing Arrival of the Viking Fleet Wallpaper A History of Vintage Transformers [Infographic]

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• Programming concepts taken from the arts and humanities

  - by Joey Adams

  After reading Paul Graham's essay Hackers and Painters and Joel Spolsky's Advice for Computer Science College Students, I think I've finally gotten it through my thick skull that I should not be loath to work hard in academic courses that aren't "programming" or "computer science" courses. To quote the former: I've found that the best sources of ideas are not the other fields that have the word "computer" in their names, but the other fields inhabited by makers. Painting has been a much richer source of ideas than the theory of computation. — Paul Graham, "Hackers and Painters" There are certainly other, much stronger reasons to work hard in the "boring" classes. However, it'd also be neat to know that these classes may someday inspire me in programming. My question is: what are some specific examples where ideas from literature, art, humanities, philosophy, and other fields made their way into programming? In particular, ideas that weren't obviously applied the way they were meant to (like most math and domain-specific knowledge), but instead gave utterance or inspiration to a program's design and choice of names. Good examples: The term endian comes from Gulliver's Travels by Tom Swift (see here), where it refers to the trivial matter of which side people crack open their eggs. The terms journal and transaction refer to nearly identical concepts in both filesystem design and double-entry bookkeeping (financial accounting). mkfs.ext2 even says: Writing superblocks and filesystem accounting information: done Off-topic: Learning to write English well is important, as it enables a programmer to document and evangelize his/her software, as well as appear competent to other programmers online. Trigonometry is used in 2D and 3D games to implement rotation and direction aspects. Knowing finance will come in handy if you want to write an accounting package. Knowing XYZ will come in handy if you want to write an XYZ package. Arguably on-topic: The Monad class in Haskell is based on a concept by the same name from category theory. Actually, Monads in Haskell are monads in the category of Haskell types and functions. Whatever that means...

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• How to Change the Default Application for Android Tasks

  - by Jason Fitzpatrick

  When it comes time to switch from using one application to another on your Android device it isn’t immediately clear how to do so. Follow along as we walk you through swapping the default application for any Android task. Initially changing the default application in Android is a snap. After you install the new application (new web browser, new messaging tool, new whatever) Android prompts you to pick which application (the new or the old) you wish to use for that task the first time you attempt to open a web page, check your text message, or otherwise trigger the event. Easy! What about when it comes time to uninstall the app or just change back to your old app? There’s no helpful pop-up dialog box for that. Read on as we show you how to swap out any default application for any other with a minimum of fuss. Latest Features How-To Geek ETC How to Change the Default Application for Android Tasks Stop Believing TV’s Lies: The Real Truth About "Enhancing" Images The How-To Geek Valentine’s Day Gift Guide Inspire Geek Love with These Hilarious Geek Valentines RGB? CMYK? Alpha? What Are Image Channels and What Do They Mean? How to Recover that Photo, Picture or File You Deleted Accidentally Now Together and Complete – McBain: The Movie [Simpsons Video] Be Creative by Using Hex and RGB Codes for Crayola Crayon Colors on Your Next Web or Art Project [Geek Fun] Flash Updates; Finally Supports Full Screen Video on Multiple Monitors 22 Ways to Recycle an Altoids Mint Tin Make Your Desktop Go Native with the Tribal Arts Theme for Windows 7 A History of Vintage Transformers: Decepticons Edition [Infographic]

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• Ur/Web new purely functional language for web programming?

  - by Phuc Nguyen

  I came across the Ur/Web project during my search for web frameworks for Haskell-like languages. It looks like a very interesting project done by one person. Basically, it is a domain-specific purely functional language for web programming, taking the best of ML and Haskell. The syntax is ML, but there are type classes and monad from Haskell, and it's strictly evaluated. Server-side is compiled to native code, client to Javascript. See the slides and FAQ page for other advertised advantages. Looking at the demos and their source code, I think the project is very promising. The latest version is something 20110123, so it seems to be under active development at this time. My question: Has anybody here had any further experience with it? Are there problems/annoyances compared to Haskell, apart from ML's slightly more verbose syntax? Even if it's not well known yet, I hope more people will know of it. OMG this looks very cool to me. I don't want this project to die!!

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• How to Create Geo-Reminders in Android with GeoNote

  - by Zainul Franciscus

  Unlike most reminders that remind you to do a certain action at a desired time, GeoNote gives you reminders when you enter a location. If you’re a big fan of location-based services, then GeoNote is the perfect reminder for you. Image by Menino.Us GeoNote is one of the few Geo-Reminder applications that are available on the market for free. Its simple interface allows us to create To-Do list quickly. Just click the “Add Location” button to add your first note Latest Features How-To Geek ETC Inspire Geek Love with These Hilarious Geek Valentines RGB? CMYK? Alpha? What Are Image Channels and What Do They Mean? How to Recover that Photo, Picture or File You Deleted Accidentally How To Colorize Black and White Vintage Photographs in Photoshop How To Get SSH Command-Line Access to Windows 7 Using Cygwin The How-To Geek Video Guide to Using Windows 7 Speech Recognition A History of Vintage Transformers [Infographic] Amazon Finally Adds Real Page Numbers to the Kindle Now You Can Print Google Docs and Gmail through Google Cloud Print AppBrain Enables Direct-to-Phone Installation Again Build a DIY Clapper to Hone Your Electronics Chops How to Kid Proof Your Computer’s Power and Reset Buttons

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• Data binding in web UI frameworks, what's the deal?

  - by c-smile

  I believe that most of modern Web frameworks that pretend to be MVC ones also has a notion of data binding in one form or another. Examples: AngularJS, EmberJS, KnockoutJS, etc. I am assuming that "data binding" is a declarative definition (oxymoron, no?) of live link between data (a.k.a. model) and its representation (a.k.a. view). With some transformers in between (a.k.a. controllers). I understand why declarativeness is kind of appealing but also understand that as usual it comes with the price. In particular: 1. Live binding is quite heavy, either with dirty watch (high CPU consumption) or with Object.observe() (high memory consumption with high CPU load in some scenarios). 2. There is a "frame" part in the framework word, means there are some boundaries/limits that can be hard to overcome if you need slightly more than it was designed for. Quite usual time split: 90% of features are made in 10% of project time. But 10% rest take 90% of project time. I suspect (a.k.a. educated guess) that those MVC things are not helping to implement more functionality in less time... If so their usage motivation is not quite clear. As an example: last week wanted to find virtual list idea/solution. Found one in vanilla JavaScript that is 120 LOC. Implementation of the same but in AngualrJS is about 420 LOC. Most of the code there seems like a fight with the framework itself... So is my question: what benefits that MVC stuff or data binding give us? Is it just a buzzword popular among project managers or they give us something useful. If later one then what exactly?

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• How can I make sense of the word "Functor" from a semantic standpoint?

  - by guillaume31

  When facing new programming jargon words, I first try to reason about them from an semantic and etymological standpoint when possible (that is, when they aren't obscure acronyms). For instance, you can get the beginning of a hint of what things like Polymorphism or even Monad are about with the help of a little Greek/Latin. At the very least, once you've learned the concept, the word itself appears to go along with it well. I guess that's part of why we name things names, to make mental representations and associations more fluent. I found Functor to be a tougher nut to crack. Not so much the C++ meaning -- an object that acts (-or) as a function (funct-), but the various functional meanings (in ML, Haskell) definitely left me puzzled. From the (mathematics) Functor Wikipedia article, it seems the word was borrowed from linguistics. I think I get what a "function word" or "functor" means in that context - a word that "makes function" as opposed to a word that "makes sense". But I can't really relate that to the notion of Functor in category theory, let alone functional programming. I imagined a Functor to be something that creates functions, or behaves like a function, or short for "functional constructor", but none of those seems to fit... How do experienced functional programmers reason about this ? Do they just need any label to put in front of a concept and be fine with it ? Generally speaking, isn't it partly why advanced functional programming is hard to grasp for mere mortals compared to, say, OO -- very abstract in that you can't relate it to anything familiar ? Note that I don't need a definition of Functor, only an explanation that would allow me to relate it to something more tangible, if there is any.

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• Why not XHTML5?

  - by eegg

  So, HTML5 is the Big Step Forward, I'm told. The last step forward we took that I'm aware of was the introduction of XHTML. The advantages were obvious: simplicity, strictness, the ability to use standard XML parsers and generators to work with web pages, and so on. How strange and frustrating, then, that HTML5 rolls all that back: once again we're working with a non-standard syntax; once again, we have to deal with historical baggage and parsing complexity; once again we can't use our standard XML libraries, parsers, generators, or transformers; and all the advantages introduced by XML (extensibility, namespaces, standardization, and so on), that the W3C spent a decade pushing for good reasons, are lost. Fine, we have XHTML5, but it seems like it has not gained popularity like the HTML5 encoding has. See this SO question, for example. Even the HTML5 specification says that HTML5, not XHTML5, "is the format suggested for most authors." Do I have my facts wrong? Otherwise, why am I the only one that feels this way? Why are people choosing HTML5 over XHTML5?

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• Using NHibernate Criteria API to select sepcific set of data together with a count

  - by mfloryan

  I have the following domain set up for persistence with NHibernate: I am using the PaperConfiguration as the root aggregate. I want to select all PaperConfiguration objects for a given Tier and AcademicYearConfiguration. This works really well as per the following example: ICriteria criteria = session.CreateCriteria<PaperConfiguration>() .Add(Restrictions.Eq("AcademicYearConfiguration", configuration)) .CreateCriteria("Paper") .CreateCriteria("Unit") .CreateCriteria("Tier") .Add(Restrictions.Eq("Id", tier.Id)) return criteria.List<PaperConfiguration>(); (Perhaps there is a better way of doing this though). Yet also need to know how many ReferenceMaterials there are for each PaperConfiguration and I would like to get it in the same call. Avoid HQL - I already have an HQL solution for it. I know this is what projections are for and this question suggests an idea but I can't get it to work. I have a PaperConfigurationView that has, instead of IList<ReferenceMaterial> ReferenceMaterials the ReferenceMaterialCount and was thinking along the lines of ICriteria criteria = session.CreateCriteria<PaperConfiguration>() .Add(Restrictions.Eq("AcademicYearConfiguration", configuration)) .CreateCriteria("Paper") .CreateCriteria("Unit") .CreateCriteria("Tier") .Add(Restrictions.Eq("Id", tier.Id)) .SetProjection( Projections.ProjectionList() .Add(Projections.Property("IsSelected"), "IsSelected") .Add(Projections.Property("Paper"), "Paper") // and so on for all relevant properties .Add(Projections.Count("ReferenceMaterials"), "ReferenceMaterialCount") .SetResultTransformer(Transformers.AliasToBean<PaperConfigurationView>()); return criteria.List< PaperConfigurationView >(); unfortunately this does not work. What am I doing wrong? The following simplified query: ICriteria criteria = session.CreateCriteria<PaperConfiguration>() .CreateCriteria("ReferenceMaterials") .SetProjection( Projections.ProjectionList() .Add(Projections.Property("Id"), "Id") .Add(Projections.Count("ReferenceMaterials"), "ReferenceMaterialCount") ).SetResultTransformer(Transformers.AliasToBean<PaperConfigurationView>()); return criteria.List< PaperConfigurationView >(); creates this rather unexpected SQL: SELECT this_.Id as y0_, count(this_.Id) as y1_ FROM Domain.PaperConfiguration this_ inner join Domain.ReferenceMaterial referencem1_ on this_.Id=referencem1_.PaperConfigurationId The above query fails with ADO.NET error as it obviously is not a correct SQL since it is missing a group by or the count being count(referencem1_.Id) rather than (this_.Id). NHibernate mappings: <class name="PaperConfiguration" table="PaperConfiguration"> <id name="Id" type="Int32"> <column name="Id" sql-type="int" not-null="true" unique="true" index="PK_PaperConfiguration"/> <generator class="native" /> </id> <!-- IPersistent --> <version name="VersionLock" /> <!-- IAuditable --> <property name="WhenCreated" type="DateTime" /> <property name="CreatedBy" type="String" length="50" /> <property name="WhenChanged" type="DateTime" /> <property name="ChangedBy" type="String" length="50" /> <property name="IsEmeEnabled" type="boolean" not-null="true" /> <property name="IsSelected" type="boolean" not-null="true" /> <many-to-one name="Paper" column="PaperId" class="Paper" not-null="true" access="field.camelcase"/> <many-to-one name="AcademicYearConfiguration" column="AcademicYearConfigurationId" class="AcademicYearConfiguration" not-null="true" access="field.camelcase"/> <bag name="ReferenceMaterials" generic="true" cascade="delete" lazy="true" inverse="true"> <key column="PaperConfigurationId" not-null="true" /> <one-to-many class="ReferenceMaterial" /> </bag> </class> <class name="ReferenceMaterial" table="ReferenceMaterial"> <id name="Id" type="Int32"> <column name="Id" sql-type="int" not-null="true" unique="true" index="PK_ReferenceMaterial"/> <generator class="native" /> </id> <!-- IPersistent --> <version name="VersionLock" /> <!-- IAuditable --> <property name="WhenCreated" type="DateTime" /> <property name="CreatedBy" type="String" length="50" /> <property name="WhenChanged" type="DateTime" /> <property name="ChangedBy" type="String" length="50" /> <property name="Name" type="String" not-null="true" /> <property name="ContentFile" type="String" not-null="false" /> <property name="Position" type="int" not-null="false" /> <property name="CommentaryName" type="String" not-null="false" /> <property name="CommentarySubjectTask" type="String" not-null="false" /> <property name="CommentaryPointScore" type="String" not-null="false" /> <property name="CommentaryContentFile" type="String" not-null="false" /> <many-to-one name="PaperConfiguration" column="PaperConfigurationId" class="PaperConfiguration" not-null="true"/> </class>

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• MVVM in a canvas with usercontrols

  - by Mauro Destro

  I have a MVVM WPF application that basically wants to be a single line diagram designer for an electrical distribution network. I have a canvas that must contains transformers, circuit breaker, lines and cables. My big problem is the design... How can i start? I think about a DesignerView, DesignerViewModel that contains an ObservableCollection of IDesignerItemViewModel that is my base class for all the element. But in this case I have to use ItemsControl to bind the content of the canvas to my collection but the pros is that I don't have to create usercontrol for each element but i'll solve most of the problems with DataTemplate (i suppose). Each element viewmodel mantain a link to a model persisted in a repository where i mantain my logical tree. Any hint about how to proceed, I have looked at many DiagramCanvas example but all of those use simple items most like simple rectangle...

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• Including two signatures, both with a 'type t' [Standard ML]

  - by Andy Morris

  A contrived example: signature A = sig type t val x: t end signature B = sig type t val y: t end signature C = sig include A B end Obviously, this will cause complaints that type t occurs twice in C. But is there any way to express that I want the two ts to be equated, ending up with: signature C = sig type t val x: t val y: t end I tried all sorts of silly syntax like include B where type t = A.t, which unsurprisingly didn't work. Is there something I've forgotten to try? Also, I know that this would be simply answered by checking the language's syntax for anything obvious (or a lack of), but I couldn't find a complete grammar anywhere on the internet. (FWIW, the actual reason I'm trying to do this is Haskell-style monads and such, where a MonadPlus is just a mix of a Monad and an Alternative; at the moment I'm just repeating the contents of ALTERNATIVE in MONAD_PLUS, which strikes me as less than ideal.)

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• NHibernate Projection Components

  - by reggieboyYEAH

  Hello guys im trying to hydrate a DTO using projections in NHibernate this is my code IList<PatientListViewModel> list = y.CreateCriteria<Patient>() .SetProjection(Projections.ProjectionList() .Add(Projections.Property("Birthdate"), "Birthdate") .Add(Projections.Property("Doctor.Id"), "DoctorId") .Add(Projections.Property("Gender"), "Gender") .Add(Projections.Property("Id"), "PatientId") .Add(Projections.Property("Patient.Name.Fullname"), "Fullname") ) .SetResultTransformer(Transformers.AliasToBean<PatientListViewModel>()) .List<PatientListViewModel>(); this code is throwing an exception? anyone know what is the problem? here is the error message Message: could not resolve property: Patient.Name.Fullname of: OneCare.Domain.Entities.Patient

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• How to implement paging in NHibernate with a left join query

  - by Gabe Moothart

  I have an NHibernate query that looks like this: var query = Session.CreateQuery(@" select o from Order o left join o.Products p where (o.CompanyId = :companyId) AND (p.Status = :processing) order by o.UpdatedOn desc") .SetParameter("companyId", companyId) .SetParameter("processing", Status.Processing) .SetResultTransformer(Transformers.DistinctRootEntity); var data = query.List<Order>(); I want to implement paging for this query, so I only return x rows instead of the entire result set. I know about SetMaxResults() and SetFirstResult(), but because of the left join and DistinctRootEntity, that could return less than x Orders. I tried "select distinct o" as well, but the sql that is generated for that (using the sqlserver 2008 dialect) seems to ignore the distinct for pages after the first one (I think this is the problem). What is the best way to accomplish this?

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• Finding parents where child collection does not contain an item with a specific property value

  - by Colin Bowern

  I am trying to get a list of parents where the child collection does not contain an item of a specific type. The LINQ equivalent would be something like: dataset.Where(x => x.Items.FirstOrDefault(y => y.Type.Code == "ABC") == null) The object model is Parent Child (Items) Type Code If Parent is my aggregate root, how would I model this in NHibernate criteria/query? Here's my first attempt: var results = session.CreateCriteria<Parent>() .CreateCriteria("Items") .CreateCriteria("Type") .Add(Restrictions.Not(Restrictions.Eq("Code", "ABC"))) .SetResultTransformer(Transformers.DistinctRootEntity) .List<Parent>(); This doesn't seem to return the right entities - it just returns them all.

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• Are we asking too much of transactional memory?

  - by Carl Seleborg

  I've been reading up a lot about transactional memory lately. There is a bit of hype around TM, so a lot of people are enthusiastic about it, and it does provide solutions for painful problems with locking, but you regularly also see complaints: You can't do I/O You have to write your atomic sections so they can run several times (be careful with your local variables!) Software transactional memory offers poor performance [Insert your pet peeve here] I understand these concerns: more often than not, you find articles about STMs that only run on some particular hardware that supports some really nifty atomic operation (like LL/SC), or it has to be supported by some imaginary compiler, or it requires that all accesses to memory be transactional, it introduces type constraints monad-style, etc. And above all: these are real problems. This has lead me to ask myself: what speaks against local use of transactional memory as a replacement for locks? Would this already bring enough value, or must transactional memory be used all over the place if used at all?

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• Haskell optimization of a function looking for a bytestring terminator

  - by me2

  Profiling of some code showed that about 65% of the time I was inside the following code. What it does is use the Data.Binary.Get monad to walk through a bytestring looking for the terminator. If it detects 0xff, it checks if the next byte is 0x00. If it is, it drops the 0x00 and continues. If it is not 0x00, then it drops both bytes and the resulting list of bytes is converted to a bytestring and returned. Any obvious ways to optimize this? I can't see it. parseECS = f [] False where f acc ff = do b <- getWord8 if ff then if b == 0x00 then f (0xff:acc) False else return $ L.pack (reverse acc) else if b == 0xff then f acc True else f (b:acc) False

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• Nhibernate Left Outer Join Return First Record of the Join

  - by Touch

  I have the following mappings of which Im trying to bring back 0 - 1 Media Id associated with a Product using a left join (I havnt included my attempt as it confuses the situation) ICriteria productCriteria = Session.CreateCriteria(typeof(Product)); productCriteria .CreateAlias("ProductCategories", "pc", JoinType.InnerJoin) .CreateAlias("pc.ParentCategory", "category") .CreateAlias("category.ParentCategory", "group") .Add(Restrictions.Eq("group.Id", 333)) .SetProjection( Projections.Distinct( Projections.ProjectionList() .Add(Projections.Alias(Projections.Property("Id"), "Id")) .Add(Projections.Alias(Projections.Property("Title"), "Title")) .Add(Projections.Alias(Projections.Property("Price"), "Price")) .Add(Projections.Alias(Projections.Property("media.Id"), "SearchResultMediaId")) // I NEED THIS ) ) .SetResultTransformer(Transformers.AliasToBean<Product>()); IList<Product> products = productCriteria .SetFirstResult(0) .SetMaxResults(10) .List<Product>(); I need the query to populate the SearchResultMediaId with Media.Id, I only want to bring back the first Media in a left outer join, as this is 1 to many association between Product and Media Product is mapped to Media in the following way mapping.HasManyToMany<Media>(x => x.Medias) .Table("ProductMedias") .ParentKeyColumn("ProductId") .ChildKeyColumn("MediaId") .Cascade.AllDeleteOrphan() .LazyLoad() .AsBag(); Any Help would be fantastic.

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• hibernate createSQL how to cache it?

  - by cometta

  If i use Criteria statement, i able to use cache easily. but when i using custom CREATESQL, like below, how do i cache it? Query query = getHibernateTemplate().getSessionFactory().getCurrentSession().createSQLQuery( " select company_keysupplier.ddiv as ddiv, company_division.name as DIVISION, company_keysupplier.ddep as ddep,company_department.name as DEPARTMENT"+ " from company_keysupplier "+ " left join company_division on "+ " (company_keysupplier.ddiv= company_division.division_code and company_keysupplier.survey_num=company_division.survey_num) "+ " left join company_department on "+ " (company_keysupplier.ddep= company_department.department_code and company_keysupplier.survey_num=company_department.survey_num) "+ " where company_keysupplier.sdiv = :sdiv and company_keysupplier.sdep = :sdep and company_keysupplier.survey_num= :surveyNum " + " order by company_division.name, company_keysupplier.ddep " ) .addScalar("ddiv") .addScalar("ddep") .addScalar("DIVISION") .addScalar("DEPARTMENT") .setResultTransformer(Transformers.aliasToBean(IssKeysupplier.class)); query.setString("sdiv", sdiv); query.setString("sdep", sdepartment); query.setBigInteger("surveyNum", survey_num); //i tried query.setCachable(true) fail...... List result= (List<IssKeysupplier>)query.list(); return result;

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