Discriminated unions or sum types are a natural way to model logical OR. Often you have a property that distributes over OR. Say, in F# (used throughout the article, though the ideas should apply equally well to any ML), you can write a combinator of the type: P<'T1> → P<'T2> → P<Choice<'T1,'T2>> How to go from here to a nice set of combinators that would handle an arbitrary union? This question has been on my mind for a while, and finally I have an acceptable solution. As a disclaimer, at the level of [...]

There is news on the faster F# Printf.* story. We released an alternative implementation as a package today. NuGet: IntelliFactory.Printf Source: https://bitbucket.org/IntelliFactory/printf Some background: F# Printf.* functions are a very nice interface for formatted printing, but the default implementation is quite slow, which is undesirable for production use (say, for logging inside a server). I believe the F# team is addressing this for their next release - and when it comes, it is going to be aw[...]

There recently was an interesting SO question on F# Printf.* family of functions: http://stackoverflow.com/questions/11559440/how-to-manage-debug-printing-in-f It is known that these functions are very slow. Slow enough for most people to avoid them entirely, despite the advantages they offer in verifying argument types. What I did not know is that these functions are so slow that a few lines of simple user code can speed them up, without changing the interface: With this code I get from 2x to 10x [...]

We have just released a new version (2.4.85) of WebSharper, our web development framework and F#-to-JavaScript compiler. The main highlight of this release is experimental support for easy cloud deployment of your applications with AppHarbor. Small AppHarbor deployments are currently free, which is great news for individual developers and small companies. How to get it to work: Set up a GitHub or Bitbucket repository Set up an AppHarbor account Connect the two, according to AppHarbor instructions, so th[...]

The annual CUFP workshop is a place where people can see how others are using functional programming to solve real world problems; where practitioners meet and collaborate; where language designers and users can share ideas about the future of their favorite language; and where one can learn practical techniques and approaches for putting functional programming to work.