Rash thoughts about .NET, C#, F# and Dynamics NAV.

"Every solution will only lead to new problems."

Friday, 7. May 2010

Using a MailboxProcessor to speedup “FAKE – F# MAKE”

Filed under: F#,FAKE - F# Make — Steffen Forkmann at 11:37 Uhr

Earlier today I released “FAKE – F# Make” version 1.10.0. This new release contains a lot path issue fixes for Mono and a new architecture for logging and tracing.

A guy named Joel Mueller had an awesome idea and sent me some patches. He noticed that TraceHelper.fs writes all messages synchronously to the console and/or a XML output file, which means the actual build operations must wait on the writing of hundreds of trace messages, slowing down the actual build.

His idea was to use a MailboxProcessor to buffer up the trace messages and write them out asynchronously, so that the actual build can proceed at full speed.

type Message =

    { Text      : string

      Color     : ConsoleColor

      Newline   : bool

      Important : bool}


/// ….


let buffer = MailboxProcessor.Start (fun inbox ->

    let rec loop () =

        async {

            let! (msg:Message) = inbox.Receive()

            match traceMode with

            | Console -> logMessageToConsole msg

            | Xml     -> appendXML msg.Text


            return! loop ()}


    loop ())     

Now all internal logging and tracing functions can post their their messages to the inbox of the MailboxProcessor:

/// Logs the specified string (via message buffer)

let logMessage important newLine message =

    match traceMode with

    | Console ->

        { Text = message;

          Important = important;

          Newline = newLine;

          Color = ConsoleColor.White }

          |> buffer.Post

    | Xml     ->

        { defaultMessage with

            Text = sprintf "<message><![CDATA[%s]]></message>"

                     message }

          |> buffer.Post

This idea reduces the build time of FAKE’s self build from 3 min. to 2 min. Which is really amazing, since I didn’t have to change anything in the build script. This version is compatible to the last released version.

Please download “FAKE – F# Make” version 1.10.0 and tell me what you think.

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Tuesday, 13. April 2010

“FAKE – F# Make” and NaturalSpec released

Filed under: F#,FAKE - F# Make,Visual Studio — Steffen Forkmann at 8:06 Uhr

Yesterday Microsoft released the RTM versions of Visual Studio 2010, .NET Framework 4.0 and F# and so it is time to announce the first official releases of “Fake – F# Make” and NaturalSpec. Both projects are now compatible with Visual Studio 2010 RC and RTM and the corresponding F# versions.

Fake – F# Make version 1.0.0

"FAKE – F# Make" is a build automation system, which is intended to provide a much better tooling support than XML-based build languages like MSBuild or NAnt. Due to its integration in F#, all benefits of the .NET Framework and functional programming can be used, including the extensive class library, powerful debuggers and integrated development environments like Visual Studio 2008, Visual Studio 2010 or SharpDevelop, which provide syntax highlighting and code completion.

Like F# itself the new build language was designed to be succinct, typed, declarative, extensible and easy to use.

NaturalSpec version 1.0.0

NaturalSpec is a UnitTest framework based on NUnit and completely written in F# – but you don’t have to learn F# to use it. The idea is that you can write your spec mostly in a natural language like in the following sample:


let “When removing an element from a list it should not contain the element“() =

  Given [1;2;3;4;5]                 // "Arrange" test context

    |> When removing 3              // "Act"

    |> It shouldn’t contain 3       // "Assert"

    |> It should contain 4          // another assertion

    |> It should have (Length 4)    // Assertion for length

    |> It shouldn’t have Duplicates // it contains duplicates ?

    |> Verify                       // Verify scenario

If you have any questions about the projects feel free to contact me.

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Sunday, 14. February 2010

“FAKE – F# Make” 0.29 released – Ready for F# February 2010 CTP and .NET 4.0 RC

Filed under: English posts,F#,FAKE - F# Make — Steffen Forkmann at 16:56 Uhr

Last week I released version 0.29 of my build automation tool “FAKE – F# Make”. The new version comes along with a couple of changes which I will now describe.

F# February 2010 CTP and .NET 4.0 RC

“FAKE – F# Make” should be completely compatible with both, the F# February 2010 CTP and the F# version which is included in Visual Studio 2010 RC.

FAKE self build and binaries on teamcity.codebetter.com

Since “FAKE – F# Make” is a build automation tool, it was always used for it’s own build process. Now this build process could be moved to an open CI server at teamcity.codebetter.com. If you login as a guest you can download the latest “FAKE – F# Make” binaries from there.

FAKE on build servers without F#

With the new F# CTP there is no longer a need for installing F# on the build agents. In fact FAKE itself was built on build agents which don’t have a F# installation.

If you want to create such build scripts you have to do the following:

  1. Download the standalone zip file of the F# CTP
  2. Put the bin subfolder into your project tree
  3. Modify the FSIPath value in the FAKE.exe.config file to match your FSharp bin folder
    1. If you copy the contents the F# bin folder into ./tools/FSharp/ it should just work.

If you have F# projects you also need to modify your .fsproj files like this:

<Import Project="..\..\..\tools\FSharp\Microsoft.FSharp.Targets" />

This modifications should take care that MSBuild will use the F# compiler from your tools paths.

Generate your documentations with “docu”

“What’s a docu? A documentation generator for .Net that isn’t complicated, awkward, or difficult to use. Given an assembly and the XML that’s generated by Visual Studio, docu can produce an entire website of documentation with a single command.” [docu Homepage]

“FAKE – F# Make” 0.29 is bundled with this new documentation tool which can easily convert your xml-Documentation into some nice html pages. You can use the tool with the new Docu task like this:

Target? GenerateDocumentation <-

    fun _ ->

        Docu (fun p ->

            {p with

               ToolPath = @".\tools\FAKE\docu.exe"

               TemplatesPath = @".\tools\FAKE\templates"

               OutputPath = docDir })

            (buildDir + "MyAssembly.dll")

You will also need the docu templates, which you can download from the product homepage. I’m planning to bundle some basic templates with the next version of FAKE.

What’s next?

At the moment I’m working on ILMerge task for FAKE. I hope to release this with the next version. There are also some open issues with the Mono support but since teamcity.codebetter.com is getting a mono build agent I hope to make some progress here too.

If you have any questions or ideas for new features please contact me.

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Monday, 8. February 2010

New syntactic sugar for “FAKE – F# Make” – Getting rid of magic strings

Filed under: English posts,F#,FAKE - F# Make — Steffen Forkmann at 17:58 Uhr

The new version 0.27 of “FAKE – F# Make” comes with new syntactic sugar for build targets and build dependencies. Don’t be afraid the old version is still supported – all scripts should still work with the new version.

The problem

Consider the following target definition:

let buildDir = "./build/"


Target "Clean" (fun _ ->

  CleanDir buildDir



Target "Default" (fun _ ->

  trace "Hello World from FAKE"



"Default" <== ["Clean"]


run "Default"

As you can see we are having a lot of “magic strings” for the target names and the dependency definitions. This was always a small shortcoming in FAKE, since this doesn’t allow refactoring and may result in runtime errors.

One of my goals for “FAKE – F# Make” is to remove these strings in future versions. Unfortunately this is not that easy, because it causes a lot of internal issues. In particular logging to the build server is much harder if you don’t have a target name.

The first step

As posted in a bitbucket comment by cipher we could use the “dynamic lookup operator” to remove some of the magic strings without breaking any internal code.

As a result we can rewrite the above sample as:

let buildDir = "./build/"


Target? Clean <-

    fun _ -> CleanDir buildDir


Target? Default <-

    fun _ -> trace "Hello World from FAKE"


For? Default <- Dependency? Clean


Run? Default

All magic strings suddenly disappeared. I think this syntax looks really nice, but unfortunately the strings are not really gone, since the token Default is only checked at runtime.

The idea for future versions

Since the new syntax is really just syntactic sugar I’m always interested in a better solution. Currently I’m working on a syntax using monads. The result could look like this:

let buildDir = "./build/"


let Clean = target { CleanDir buildDir }

let Default =

  target {

    trace "Hello World from FAKE"

    trace "Another line"



Default <== [Clean]

Run Default

This way the magic string are really gone, but my current problem is retrieving the target name from the let-binding name. Please leave a comment if you have an idea to solve this issue.

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Sunday, 18. October 2009

xUnit.net support in “FAKE – F# Make” 0.14

Filed under: F#,FAKE - F# Make — Steffen Forkmann at 18:09 Uhr

Yesterday I released “FAKE – F# Make” version 0.14 with xUnit.net support. The usage is very easy and similar to the usage of NUnit:

Target "xUnitTest" (fun () -> 

  let testAssemblies =

    !+ (testDir + @"\Test.*.dll")

      |> Scan



    (fun p ->

       {p with

           ShadowCopy = false;

           HtmlPrefix = testDir})



This sample works perfectly with TeamCity and creates a html-page per test project in addition:

TeamCity output

HMTL output

If you want to publish the xUnit.net test results in CruiseControl.NET just modify the build script a little:

Target "xUnitTest" (fun () -> 

  let testAssemblies =

    !+ (testDir + @"\Test.*.dll")

      |> Scan



    (fun p ->

       {p with

           ShadowCopy = false;

           HtmlPrefix = testDir;

           XmlPrefix = testDir })



Now follow the steps in the CrusieControl.NET documentation. You will need to download the xUnitSummary.xsl file and save it to your webdashboard directory. If everything works correctly you should see something like this:

CruisControl.NET output

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Wednesday, 14. October 2009

Integrating a “FAKE – F# Make” build script into CruiseControl.NET

Filed under: F#,FAKE - F# Make — Steffen Forkmann at 10:38 Uhr

Since version 0.12 the FAKE build system provides an easy way to setup build configurations for CruiseControl.NET.

“CruiseControl.NET is an Automated Continuous Integration server, implemented using the Microsoft .NET Framework.”


In this article I will show you how you can set up a FAKE build script in CruiseControl.NET. We will use the CalculatorSample which you can download from the FAKE Download page.

If you want to know how this build script works and how you could create one for your own projects please read the “Getting started with FAKE”-tutorial.

If you want to set up “FAKE – F# Make” build configurations in TeamCity please read “Integrating a "FAKE – F# Make" build script into TeamCity”.

Installing CruiseControl.NET

You can download CruiseControl.NET from thoughtworks.org. After the installation process (further instructions) you should see an empty dashboard:

CruiseControl.NET Dashboard

Installing Subversion

The CalculatorSample is using Subversion (SVN) for SourceControl, so we need to download SVN from subversion.tigris.org. I’m using the “Windows MSI installer with the basic win32 binaries” and installed them under “c:\Program Files (x86)\Subversion\”.

Installing FxCop

The CalculatorSample is using FxCop, so we need to download and install it next.

“FxCop is an application that analyzes managed code assemblies (code that targets the .NET Framework common language runtime) and reports information about the assemblies, such as possible design, localization, performance, and security improvements. Many of the issues concern violations of the programming and design rules set forth in the Design Guidelines for Class Library Developers, which are the Microsoft guidelines for writing robust and easily maintainable code by using the .NET Framework.”


Creating a FAKE Project

Now create a new folder for the CalculatorSample sources. I’m using “d:\Calculator\” for the rest of the article.

The next step is to modify the CruiseControl.NET config file (“c:\Program Files (x86)\CruiseControl.NET\server\ccnet.config” on my machine):





       <intervalTrigger name="continuous" seconds="30" initialSeconds="30"/>


    <sourcecontrol type="svn">

      <executable>c:\Program Files (x86)\Subversion\bin\svn.exe</executable>



















      <xmllogger />




In this configuration I set up a trigger which checks every 30 sec. for changes in my CalculatorSample project.

If SVN finds changes FAKE.exe is called with my build script (completeBuild.fsx).

After the build I want to merge the FxCop and NUnit output files with my build results to create a build report.

Configuring the dashboard

In order to provide a nicer output on the dashboard we need to modify the BuildPlugins section in the dashboard.config file (“c:\Program Files (x86)\CruiseControl.NET\webdashboard\dashboard.config” on my machine):












  <buildLogBuildPlugin />


     description="NCover Report"



  <xslReportBuildPlugin description="FxCop Report"


     xslFileName="xsl\fxcop-report_1_36.xsl" />

  <xslReportBuildPlugin description="NUnit Report"


     xslFileName="xsl\tests.xsl" />


As you can see we use the nant.xsl to transform the FAKE output to HTML.

Starting the build

Now if everything is configured correctly, you can tell CruiseControl.NET to run your build (press “Start” for your build project on the dashboard):

Press Start on the dashboard

Now CruiseControl.NET should use SVN to checkout the CalculatorSample sources and run the build. The output on the project page for build 1 should look like this:

Build output

Build output 2

You can also inspect the NUnit and FxCop results:

 NUnit zest results

FxCop results

Please feel free to give feedback if you have any problems with this article.

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Tuesday, 6. October 2009

“FAKE – F# Make” Version 0.10 released

Filed under: F#,FAKE - F# Make — Steffen Forkmann at 11:59 Uhr

I just released a new version of my Open Source Build Automation Framework “FAKE – F# Make”. You can read more about FAKE on the project website or in the Getting started with "FAKE – F# Make"-article.

Although the new release contains many bugfixes, I only want to show the two major improvements here.

1. FAKE 0.10 uses FSI instead of FSC

From now on FAKE uses the “F# Interactive” (fsi.exe) instead of the F# Compiler (fsc.exe) to run the build scripts, which brings two major improvements.

No TempPath for compiled binaries needed

Due to the fact that FAKE scripts are no longer compiled at the beginning of the build process, we don’t need a temporary folder for the created binaries.

Loading modules at runtime

The #load command in F# scripts allows us to load modules at runtime. Now we are able to put reusable Targets or TargetTemplates (see below) into external build script files.

2. TargetTemplates

TargetTemplates provide an easy way to reuse common Targets. Let’s consider a (very) small sample:

Target "TraceHello" (fun () ->

  trace "Hello World from FAKE"


This Target “TraceHello” traces a “Hello World” string into our build log. Now we want it to be slightly more generic and to trace a custom string. We can do this by using a TargetTemplate:

/// createTraceTarget: string -> string -> Target

let createTraceTarget = TargetTemplate (fun s ->

  trace s


Now we have a template (or a function which generates targets) that gets a string for the target name and a string for the trace text and generates  a usable target:

createTraceTarget "TraceHello" "Hello World from FAKE"

createTraceTarget "Trace2" "Trace another text"

Of course the TargetTemplate function is generic and can be used with any tuple as parameter:

/// createTraceTarget: string -> string*int -> Target

let createTraceTarget = TargetTemplate (fun (s,d) ->

  trace s

  trace <| sprintf "my int: %d" d



createTraceTarget "TraceHello" ("Hello World from FAKE",2)

createTraceTarget "Trace2" ("Trace another text",42)

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Wednesday, 17. June 2009

F# BootCamp – Questions and Answers – part II – Currying

Filed under: C#,English posts,F#,FAKE - F# Make,Informatik,Mathematik,Veranstaltungen — Steffen Forkmann at 12:36 Uhr

Yesterday I was talking about F# at the .NET Developer Group Braunschweig. It was my first talk completely without PowerPoint (just Live-Coding and FlipChart) and I have to admit this is not that easy. But the event was really a big fun and we covered a lot of topics like FP fundamentals, concurrency and domain specific languages (of course I showed “FAKE – F# Make”).

Now I have a bit time before I go to the next BootCamp in Leipzig. Today Christian Weyer will show us exciting new stuff about WCF and Azure.

In the meanwhile I will write here about another important question (see first article) from the F# BootCamp in Leipzig:

Question 4 – Try to explain “Currying” and “Partial Application”. Hint: Please show a sample and use the pipe operator |>.

Obviously this was a tricky question for FP beginners. There are a lot of websites, which give a formal mathematical definition but don’t show the practical application.

“Currying … is the technique of transforming a function that takes multiple arguments (or more accurately an n-tuple as argument) in such a way that it can be called as a chain of functions each with a single argument”


I want to show how my pragmatic view of the terms here, so let’s consider this small C# function:

public int Add(int x, int y)
   return x + y;

Of course the corresponding F# version looks nearly the same:

let add(x,y) = x + y

But let’s look at the signature: val add : int * int –> int. The F# compiler is telling us add wants a tuple of ints and returns an int. We could rewrite the function with one blank to understand this better:

let add (x,y) = x + y

As you can see the add function actually needs only one argument – a tuple:

let t = (3,4)         // val t : int * int
printfn "%d" (add t)  // prints 7 – like add(3,4)

Now we want to curry this function. If you’d ask a mathematician this a complex operation, but from a pragmatic view it couldn’t be easier. Just remove the brackets and the comma – that’s all:

let add x y = x + y

Now the signature looks different: val add : int -> int –> int

But what’s the meaning of this new arrow? Basically we can say if we give one int parameter to our add function we will get a function back that will take only one int parameter and returns an int.

let increment = add 1      // val increment : (int -> int)
printfn "%d" (increment 2) // prints 3

Here “increment” is a new function that uses partial application of the curryied add function. This means we are fixing one of the parameters of add to get a new function with one parameter less.

But why are doing something like this? Wouldn’t it be enough to use the following increment function?

let add(x,y) = x + y       // val add : int * int -> int 
let increment x = add(x,1) // val increment : int -> int
printfn "%d" (increment 2) // prints 3

Of course we are getting (nearly) the same signature for increment. But the difference is that we can not use the forward pipe operator |> here. The pipe operator will help us to express things in the way we are thinking about it.

Let’s say we want to filter all even elements in a list, then calculate the sum and finally square this sum and print it to the console. The C# code would look like this:

var list = new List<int> {4,2,6,5,9,3,8,1,3,0};

If we don’t want to store intermediate results we have to write our algorithm in reverse order and with heavily use of brackets. The function we want to apply last has to be written first. This is not the way we think about it.

With the help of curried functions, partial application and the pipe operator we can write the same thing in F#:

let list = [4; 2; 6; 5; 9; 3; 8; 1; 3; 0]

let square x = x * x
 |> List.filter (fun x -> x % 2 = 0) // partial application
 |> List.sum
 |> square
 |> printfn "%A"                     // partial application

We describe the data flow in exactly the same order we talked about it. Basically the pipe operator take the result of a function and puts it as the last parameter into the next function.

What should we learn from this sample?

  1. Currying has nothing to do with spicy chicken.
  2. The |> operator makes life easier and code better to understand.
  3. If we want to use |> we need curryied functions.
  4. Defining curryied functions is easy – just remove brackets and comma.
  5. We don’t need the complete mathematical theory to use currying.
  6. Be careful with the order of the parameter in a curryied function. Don’t forget the pipe operator puts the parameter from the right hand side into your function – all other parameters have to be fixed with partial application.
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Wednesday, 15. April 2009

Integrating a “FAKE – F# Make” build script into TeamCity

Filed under: F#,FAKE - F# Make,Tools,Visual Studio — Steffen Forkmann at 11:00 Uhr

This artile has been moved to http://fsharp.github.io/FAKE/teamcity.html

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Tuesday, 14. April 2009

Writing custom C# tasks for “FAKE – F# Make”

Filed under: C#,F#,FAKE - F# Make — Steffen Forkmann at 15:37 Uhr

This post has been moved to http://fsharp.github.io/FAKE/customtasks.html

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