Future plans for FsCheck

Because of a recent question on HubFS, I made my future plans for FsCheck public. I'm re-iterating them here:

• smaller bug fixes, some cleaning (mostly done)
• adding FsCheck.fsi module declaration & comments
• Feature: derive generators from types of arguments (mostly done)
• Feature: ability to group properties in classes, and check the class with one command (mostly done)
• Investigate using FsCheck with unit testing frameworks like MbUnit & co, or generally how to use it in practice (currently active)
• putting the project on codeplex + clarifying license . I'm checking compatibility with the QuickCheck license, but I'm aiming for a permissive license, like the new BSD license.

I intend to finalize this before the end of the year.

Finally, you can help by answering the following question. How are you using FsCheck? Do you have a separate console app that you run that contains your properties, or do you use F# interactive with the properties inline, or something else?

Technorati: F#,random testing,FsCheck

How to use named arguments in F#

Named arguments are a little-known feature of F#, that is actually very useful when calling heavily overloaded members. The DateTime constructor is one such example: it has twelve overloads, and I can never remember what (in C#) DateTime d = new DateTime(2008,11,12) means. Is it December 11th or 11 November (as we would say it in Dutch)? Fortunately, in F# there is a nice solution for this: you can always use the names of the formal arguments to specify a named argument. This not only clarifies what overload you're calling, you can also easily change the order of the arguments. For example:

let d = new DateTime(month=12, day=11, year=2008)

makes it very clear that we're talking about December 11th here. If you're from the US, it even looks 'normal'. Europeans may like:

let d' = new DateTime(day=11, month=12, year=2008)

For F#, it's all the same.

You can also mix positional with named arguments, and if the object has setters, you can use these to. For details, read Section 8.4.5 in the F# (draft) language spec.

Technorati: F#,named arguments