Is there a way to run F# code in C#? I have written an app in C# - I'd like to provide it the ability to execute F#, read Record objects, enumerate lists from F#. What is the current solution for this? I know in the future there will be probably be a way to do this via an update to Roslyn. Also, curious how to run F# code in F#, currently. Is there a way to do that easily?
Currently, you have to make the F# a library, and then call it from C#. Since F# is just .NET, using the F# library is (mostly) just like using any other C# library. You might want to look into FSharpX for this portion, however, as it provides some utilities to ease calling F# from C# and vice versa.
If you want to compile the F# dynamically from C#, you'll need to use the F# CodeDom implementation from the F# Power Pack. This will let you use CodeDom to compile F# on the fly, and then execute it from C#.
Note that Roslyn will not help here, even when it's released, as it won't support F# as a code model, only C# and VB.Net. It would potentially be possible to use Roslyn to manipulate and compile C# from within F#, but not the other way around.
In addition to the options that Reed already mentioned, there are a two other alternatives based on using the F# Interactive - you can either run it as a separate process or you could use the open-source release to reference it and call it directly (which is quite challenging, though).
So in summary, you have three options:
You can start the fsi.exe process and evaluate F# code in the F# Interactive environment (by sending F# code to the process by standard input). The F# binding for MonoDevelop is a good example how to do this (see InteractiveSession.fs).
The only difficulty is communication between the two processes, but I think this should be doable using a .NET remoting (or WCF) channel between the two. You can also just read the standard output from F# Interactive, but that might be a bit too simple.
You could use the open-source release of F# compiler & tools to reference relevant parts of the F# compiler and call them (as a library) to evaluate F# code. This would be the best option and it would give you pretty much the same options you get with interactive C# from Roslyn.
Sadly, this is not quite an easy task - I was playing with the idea of doing this and I made some progress (I can share that), but it is not done yet. The idea is to take the source code of fsi.exe (here), remove all UI and turn it into a library.
Using CodeDOM, you can invoke the F# compiler (fsc.exe) to compile F# code into a stand-alone application (or library), load it dynamically and run it. A disadvantage is that this will start a new instance of the compiler each time you use it and so it may be a bit slow (depends on your scenario)
Since the question has been asked, there has been a lot of exciting development :-)
You can now do this really easily using the F# Compiler Services project:
The F# compiler services package is a component derived from the F# compiler source code that exposes additional functionality for implementing F# language bindings, additional tools based on the compiler or refactoring tools. The package also includes F# interactive service that can be used for embedding F# scripting into your applications.
Related
Is there any C# interpreter that can be used inside C++ and yet still allow .Net access?
I want to use C# scripts for games and I'm not sure how to proceed with that.
You can write a simple class in C#, let's call it ScriptRunner that would take your C# code as input, compile it at runtime to produce a new assembly in memory, then it will use Reflection to load a specific Type from this new assembly, and will run some method with an expected name.
Then, use COM Interop (for example) to create a ScriptRunner .NET object from your C++ native application, and you'll be able to use it to run scripts.
Start with:
var myProvider = Microsoft.CSharp.CSharpCodeProvider.CreateProvider();
var myCompiler = myProvider.CreateCompiler();
and it's really easy to continue on your own by using IntelliSense to see what's on the ICodeCompiler interface.
If you've got some specific questions about this approach please ask.
C# is not an interpreted language, it is a compiled language.
You can write C# scripts, but why not use Python or Ruby or Lua or some other true-blue scripting language?
I feel somewhat dirty mentioning this, but it looks like there is an ECMA compliant C# scripting engine.
I believe C# is a compiled language only. Your best bet would be to call the csharp compiler (csc.exe) and load the assembly dynamically.
YOu can have .net dlls and use them in your C++ code.
Is it C++ or C++/CLI? If it's the "normal" C++ I don't think it will be possible to use C# as it is a compiled language and a managed one, your best bet would be to use the managed version of C++ and compile the C# code, then load it.
I've never tried to do that but I think C# is definitely not a suitable language for scripting, for your purpose Lua or Python (for example) are certainly better...
I assume you want to use C++ for DirectX/OpenGL support and then want to load in the entire .Net Framework on top of that to support scripting? That would be a very heavy footprint if it were possible. Since C# is compiled into bytecode (just like Java), you would have to precompile your scripts.
Your best best is to to use an opensource scripting language (php, lua, etc).
C++ and C# are quite simmilar programming languages, in my opinion. If a C++ code needs to be ported to platform where C# is the only supported platform, how much work will need to be done?
Should I get ready, that most of the C++ code will need to be rewritten to C#? Or, because of language simmilarities, should refactoring be quite easy and straightforward?
I am aware, that it will depend on the application itself, but I am asking in general.
I have done a major port of a C++ application to C# recently. Overall I thought it was a pleasant experience. These are the steps that I took, they might or might not apply to your application.
Get the "scaffolding" in place in C#, design your architecture. This is the time to get in major architecture changes from the existing application if you choose to do so.
Get your tests in place. I can't over-emphasize this one. Since you are porting an existing application you should have a set of tests already in place that verify the correct behavior of your application. You can and should reuse these tests for your C# application. This is the one thing that gives you an edge when porting - you know (and have written) already many of the tests you want. Start porting your test project.
Put in method stubs for your C# methods that reflect the existing C++ methods. Given the framework support in C# some methods might not be needed at all anymore, or are very simplified - this is the time to decide.
Copy and paste. Yes I used copy and paste for most of the C++ code - all the flow statements basically can be reused if you are careful. Once pasted go through line by line, many things like use of pointers etc. must be rewritten to use a equivalent C# type.
Once you have re-written a method in such a way, do the obvious re-factoring given the framework support / helper classes you might have been lacking in C++ but are readily available in C#. Also naming conventions for variables etc. can be changed here, should be straightforward given the built in support for this in VS 2010.
Run your tests! Test early and often that the overall framework you have in place so far produces the exact same output as your C++ application which you can use as a reference. This is also the time to add missing tests.
Refactor, Refactor, Refactor. Every application ages, and so did your C++ application most likely. Look closely at the underlying design and simplify and remove as much as possible. Verify at each step by running your tests.
First thing first, this is porting and not refactoring. Also I think it's an extremely bad idea.
It is true that you could (with a lot of work) port C++ to unsafe C#, but saying that the syntax is very similar is a bit of a stretch. In fact, following the same line of reasoning you could port C++ to any other C derived language, and it would be equally painful.
Again, if you do it expect a shedload of rework. It's more than likely gonna take you more than re-coding it from scratch using the existing code as mere model, which is in my opinion a better and less messy option.
Just compile the C++ code with the /clr compiler option. That will translate the code to IL, it can execute on most any .NET enabled platform. There are very few C++ constructs that cannot be translated, it would have to use non-standard compiler extensions like __fastcall.
However, I suspect that you will find out that the platform requires verifiable code. Which is the common reason why a platform would restrict code to a .NET compliant language. I cannot guess at this since you didn't mention the execution environment. Native C++ translated to IL is not verifiable due to pointer manipulations. If that's the case then you are looking at a pretty drastic rewrite.
I'd be interested to know where C# is the "only supported platform".
The problem of rewriting in a new language can be whether you need to rewrite every single part of the code and cannot use any of the old code at all. Sometimes it is best, even when doing a rewrite, to make it more of a refactor: rewrite some parts of the code, move others. The existing code is known to work and can be tricky to reproduce. And it takes time. There needs to be a good reason to do a full rewrite.
.NET supports a version of C++, and Visual Studio also comes with Visual C++ to build standard C++, so consider whether or not you can make this a phased transformation, and whether or not you really have to rewrite the whole thing.
Porting C++ code to C# will not be that hard, assuming that all your dependent libraries have existing C# counterparts. Lack of dependencies is the most likely pitfall. The core concepts of your program, such as inheritance, heap, references, data structures, should be fairly easily translatable.
This is assuming that you don't invoke any specific low level behaviour such as custom memory management, because C# does not really support that kind of thing and you could have a serious problem there.
We all knows that C# is a static language while Python is a dynamic language. But I want to know what are the features that Python has and c# does not. Also, is it advisable/beneficial to use IronPython with c# in the same application?
Also what points I should focus to learn before I try to convince my boss to use IronPython?
In other words, what points I can give to my boss to convince him to use IronPython?
Don't. If you don't know why you should use a new tool and for what, don't try to convice anybody to use it. At work, you should try to solve problems with the best tools for the task, not throw the fanciest tools avaiable at your problems just because they're fancy.
Learn IronPython, maybe make a small side project in it, find out what the strenghts are. Then if you think these strengths are useful for the project you're working on (e.g. for "glue code", plugins, macros etc.), convice your boss to use them.
One of IronPython's key advantages is in its function as an extensibility layer to application frameworks written in a .NET language. It is relatively simple to integrate an IronPython interpreter into an existing .NET application framework. Once in place, downstream developers can use scripts written in IronPython that interact with .NET objects in the framework, thereby extending the functionality in the framework's interface, without having to change any of the framework's code base.
IronPython makes extensive use of reflection. When passed in a reference to a .NET object, it will automatically import the types and methods available to that object. This results in a highly intuitive experience when working with .NET objects from within an IronPython script.
Source - Wikipedia
I have a small (~2000 lines of code) class that I would like to use from both java & .NET. There are several approaches to do this - among them wrapping the class as a service, using some interop voodoo, or duplicating the code to both C# & java.
Do you know an out-of-the-box tool that accomplishes the latter - takes a simple C# class with no dependencies and converts it to an equivalent java class?
IKVM.NET does pretty good job in taking a jar file and compiling it to a managed .NET assembly.
If it is small (or in fact, even if it is large), I'm not sure of the wisdom of mechanical translation tools; I've simply never had much joy with them. However, one option would be to write the .NET code in J#.
But I stress - if it was me, I'd manually port it between the two manually and maintain them separately. Most of the time the differences aren't huge - signed bytes, the boxing differences, etc. Of course, anything with delegates will need changing - and captured variables work differently, etc etc.
There used to be a COM bridge and you can register C# assemblies for use in COM with regasm.exe or visual studio.
It's not really what you asked for, but I would just create a simple C# to Java translator.
The differences are not that huge and you seem to be the author of the source so you can avoid nasty constructs that are quite difficult to translate. That way your translator would be quite simple. I would go from C# to Java because C# is more expressive, and you can emulate almost all the C# functions in Java.
Actually cs2java seems to do just that.
This is list of tools I know. Sharpen or j2cstranslator looks like good options.
I'm porting a Java library to C#. I'm using Visual Studio 2008, so I don't have the discontinued Microsoft Java Language Conversion Assistant program (JLCA).
My approach is to create a new solution with a similar project structure to the Java library, and to then copy the java code into a c# file and convert it to valid c# line-by-line. Considering that I find Java easy to read, the subtle differences in the two languages have surprised me.
Some things are easy to port (namespaces, inheritance etc.) but some things have been unexpectedly different, such as visibility of private members in nested classes, overriding virtual methods and the behaviour of built-in types. I don't fully understand these things and I'm sure there are lots of other differences I haven't seen yet.
I've got a long way to go on this project. What rules-of-thumb I can apply during this conversion to manage the language differences correctly?
Your doing it in the only sane way you can...the biggest help will be this document from Dare Obasanjo that lists the differences between the two languages:
http://www.25hoursaday.com/CsharpVsJava.html
BTW, change all getter and setter methods into properties...No need to have the C# library function just the same as the java library unless you are going for perfect interface compatibility.
Couple other options worth noting:
J# is Microsoft's Java language
implementation on .NET. You can
access Java libraries (up to version
1.4*, anyways).
*actually Java 1.1.4 for java.io/lang,
and 1.2 for java.util + keep in mind that J# end of
life is ~ 2015-2017 for J# 2.0 redist
Mono's IKVM also runs Java on
the CLR, with access to other .NET
programs.
Microsoft Visual Studio 2005 comes
with a "Java language conversion
assistant" that converts Java
programs to C# programs
automatically for you.
One more quick-and-dirty idea: you could use IKVM to convert the Java jar to a .NET assembly, then use Reflector--combined with the FileDisassembler Add-in--to disassemble it into a Visual C# project.
(By the way, I haven't actually used IKVM--anyone care to vouch that this process would work?)
If you have a small amount of code then a line by line conversion is probably the most efficient.
If you have a large amount of code I would consider:
Looking for a product that does the conversation for you.
Writing a script (Ruby or Perl might be a good candidate) to do the conversion for you - at least the monotonous stuff! It could be a simple search/replace for keyword differences and renaming of files. Gives you more time/fingers to concentrate on the harder stuff.
I'm not sure if it is really the best way to convert the code line by line especially if the obstacles become overwhelming. Of course the Java code gives you a guideline and the basic structure but I think at the end the most important thing is that the library does provide the same functionality like it does in Java.