By urini

2008-08-05 12:03:10 8 Comments

Can a LINQ enabled app run on a machine that only has the .NET 2.0 runtime installed?

In theory, LINQ is nothing more than syntactic sugar, and the resulting IL code should look the same as it would have in .NET 2.0.

How can I write LINQ without using the .NET 3.5 libraries? Will it run on .NET 2.0?


@Stefan Steiger 2011-03-04 18:51:25

You can use the LINQ sources from mono (.NET for Linux) to get LINQ running on .NET 2.0.

IEnumerable<T> : yes 
IQueryable<T>  : yes
LINQ to XML : has been working in the trunk, but due to further additions, the trunk doesn't compile anymore

Someone has done it here:
LINQ for .NET 2.0

@Michael Stum 2008-08-05 12:07:41

There are some "Hacks" that involve using a System.Core.dll from the 3.5 Framework to make it run with .net 2.0, but personally I would not want use such a somewhat shaky foundation.

See here: LINQ support on .NET 2.0

  1. Create a new console application
  2. Keep only System and System.Core as referenced assemblies
  3. Set Copy Local to true for System.Core, because it does not exist in .NET 2.0
  4. Use a LINQ query in the Main method. For example the one below.
  5. Build
  6. Copy all the bin output to a machine where only .NET 2.0 is installed
  7. Run

(Requires .net 2.0 SP1 and I have no idea if bundling the System.Core.dll violates the EULA)

@Lucas 2009-05-19 15:51:35

redistributing System.Core.dll is a violation of Microsoft's license

@Jonas T 2012-12-10 12:21:23

after I built and run, there is nothing in bin folder except debug folder. :( I am building Console application in .Net 4.0 visual studio 2010.

@Michael Stum 2012-12-10 16:21:52

@JonasT If you're on .net 4.0 then this doesn't apply to you at all since it's about .net 2.0 using LINQ. Feel free to ask a separate question, giving details about your setup.

@Jonas T 2013-02-19 05:58:01

Thanks Michael. All I am looking for is that output files. I am using .net 2.0. The problem is I am using Visual Studio 2010 which does not produce any output in bin folder. Is there anyway I can download those outputs?

@Mariusz 2016-08-12 10:00:40

Licenses and patents violate common sense. There's no idea that was originated in Microsoft. All of them are built on the shoulders of previous inventions. Everything belongs to everyone and I hope one day it'll become obvious. Shift in thinking is a must, otherwise we cannot make it as humanity.

@Mauricio Scheffer 2008-12-27 02:51:12

It's weird that no one has mentioned LINQBridge. This little awesome project is a backport of LINQ (IEnumerable, but without IQueryable) and its dependencies (Func, Action, etc) to .NET 2.0. And:

If your project references LINQBridge during compilation, then it will bind to LINQBridge's query operators; if it references System.Core during compilation, then it will bind to Framework 3.5's query operators.

@Lucas 2009-05-19 15:48:53

+1 I use this a lot. Note: this is an implementation of LINQ to Objects (the IEnumerable extensions), works perfectly if using VS2008 (C# 3.0) targeting framework 2.0+. It is NOT an implementation of LINQ to SQL or other LINQ providers.

@Dmitrii Lobanov 2011-03-21 08:57:10

It's bad that LINQBridge doesn't support Linq-2-Xml :( The Linq-2-Xml makes working with Xml easy and nice.

@Jeremy 2011-08-07 06:33:31

@Dmitry Linq2Xml is how I get jobs done so quickly. Xpath is still a good alternative but not as fluent.

@ala 2011-11-17 00:34:42

I just came across BackLinq by the same author! Does anyone know what is the difference or which is latest?

@Mauricio Scheffer 2011-11-17 00:38:15

@ala : see : "BackLINQ sources have been rolled and merged into the LINQBridge project and maintained under its identity. As a result, this project site has been retired and left here for archival purposes. Please follow LINQBridge for further updates, contributions and reporting of issues."

@Dmitrii Lobanov 2012-02-21 00:40:27

The one disadvantage of LinqBridge is that it's nearly impossible to use some good mocking framework (like RhinoMocks or Moq) at it's full power when you use LinqBrige as they need reference to System.Core. RhinoMocks is usable but it's best part is unavailable as you can't reference System.Core and LinqBridge at a time.

@Mauricio Scheffer 2012-02-21 01:19:36

@DmitryLobanov : the real problem there is needing those libraries.

@Stefan Steiger 2012-08-25 09:18:13

If it doesn't support IQueryable (it doesn't), then what's the point ? ? ?

@Mauricio Scheffer 2012-08-25 13:03:57

@Quandary : Func, Action and "LINQ to objects" are very useful on their own. Personally I use them a lot more than IQueryables.

@Lucas 2009-05-19 16:19:19

Short answer:

  • LINQ to Objects: yes (IEnumerable<T>)
  • LINQ to SQL/Entities: no (IQueryable<T>)
  • LINQ to XML/DataSets: not yet?

See this question about .Net 3.5 features available automatically or with little effort when targetting .Net 2.0 from VS2008.

Basically, anything that is only "syntax sugar" and the new compilers (C# 3.0, VB 9.0) emit as 2.0-compatible IL will work. This includes many features used by LINQ such as anonymous classes, lambdas as anonymous delegates, automatic properties, object initializers, and collection initializers.

Some LINQ features use classes, interfaces, delegates, and extension methods that live in the new 3.5 assemblies (such as System.Core.dll). Redistributing these assemblies is a license violation, but they could be reimplemented. Using extension methods need only that you declare an empty System.Runtime.CompilerServices.ExtensionAttribute. LINQ to Objects relies on IEnumerable<T> extensions and several delegate declarations (the Action<T> and Func<T> families) and have been implemented in LINQBridge (as mausch mentioned). LINQ to XML and LINQ to DataSets rely on LINQ to Objects which I guess could also be implemented for .Net 2.0, but I haven't seen this done yet.

LINQ to SQL and LINQ to Entities require many new classes (DataContext/ObjectContext, lots of attributes, EntitySet<T>, EntityRef<T>, Link<T>, IQueryable<T>, etc) and expression trees, which, even if somehow reimplemented, will probably require at least .Net 2.0 SP1 to work.

@Scott Wisniewski 2008-10-10 21:30:37

I'm not sure about C#.

I do know, however, that you can write VB LINNQ code w/out the 3.5 libraries as long as you use the VS 2008 compiler to target the 2.0 framework.

You will, however, have to implement some of the LINQ methods your self.

LINQ uses a syntatic transformation to translate queries into executable code. Basically, it will take code like this:

dim q = from x in xs where x > 2 select x*4;

and convert it into code like this:

dim q = xs.where(function(x) x > 2).select(function(x) x * 4);

For the LINQ functionality that ships with the 3.5 framework, those methods are implemented as extension methods on either IEnumerable or IQueryable (there's also a bunch of methods that work on data sets too).

The default IEnumerable extension methods are defined in System.Linq.Enumerable and look like this:

public function Select(of T, R)(source as IEnumerable(of T), transform as Func(of T, R)) as IEnumerable(of R)

   'do the transformation...

end function

The IQueryable extension methods take expressions trees as arguments, rather than lambdas. They look like this:

 public function Select(of T, R)(source as IQueryable<T>, transform as Expression(of Func(of T, R))
     'build a composite IQueryable that contains the expression tree for the transformation
 end function

The expression tree versions enable you to get a tree representation of the expressions provided to the clauses which can then be used to generate SQL code (or what ever else you want).

You could probably create your own version of LINQ to objects in about a day or so. It's all pretty straight forward.

If you want to use DLINQ, then things would be a little bit more difficult.

@Lucas 2009-05-19 15:50:03

+1, however note that expression trees (for IQueryable) are only available in 3.5+

@Lucas 2009-05-19 15:50:41

.. and yes, everything you said about VB 9.0 applies to C# 3.0 (using new compiler but targetting older fx version)

@Scott Wisniewski 2009-12-02 15:34:57

But you can write your own expression tree implementation if you like.

@jdecuyper 2008-08-05 12:14:33

As far as I know the LINQ library is only available since the framework 3.0. If you want to use something similar in the framework 2.0, you would need to rewritte it yourself :) or find a similar third-party library. I only found a bit of information here but it didn't convinced me either.

@John Downey 2008-08-05 12:07:46

In theory yes, provided you distribute the LINQ specific assemblies and any dependencies. However that is in violation of Microsoft's licensing. Scott Hanselman wrote a blog post about Deploying ASP.NET MVC on ASP.NET 2.0 which is similar to what you are wanting to do.

@Jon Limjap 2008-08-05 12:07:39

No, because while you thought LINQ is really just syntactic sugar, it actually heavily used expression trees -- a feature absent in .NET 2.0.

That being said .NET 3.5 only builds up on top of .NET 2.0, and that's the reason why the IL doesn't look "different" or "special".

I do not see a reason why you shouldn't just install the .NET 3.5 Framework. Everything .NET 2.0 will work fine on it, promise :)

@Lamar 2008-12-27 04:28:22

.Net 3.0 or higher won't install on windows 2000.

@Lucas 2009-05-19 15:46:09

note: expression trees are used by IQueryable (as in LINQ to SQL), but not by IEnumerbale (as in LINQ to Objects)

@cbmeeks 2014-01-10 20:52:27

Plus, in the "Corporate" world, we literally have machines that have not been "upgraded" to .NET 2.0. Yes. Seriously, we do.

@Scott Solmer 2017-04-04 18:50:10

Windows XP requires SP3 to install .NET 3.0 or higher and certain devices running Windows XP embedded are not so simple to update.

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