Tagged: expression tree

Avoiding nulls with expression trees

I’ve blogged about this subject before, but I REALLY hate null refs. This is one of the reasons I love F# and other functional languages, null ref’s almost never happen. But, in the real world I work as a C# dev and have to live with C#’s… nuisances.

In the other post, a big problem with the dynamic proxy was that it only worked with virtual methods, so it wasn’t really all that practical. This time around I decided to try a different route and leverage expression tree’s to actually build out the if checks automatically.

For the impatient, full source available at my github and the library is available on nuget

Demonstration

Let me demonstrate the final usage first. If all of users properties and methods return null, executing this whole chain would fail starting at the null result of GetSchool(). But, by using the Option static … Read more

Implementing the game “Arithmetic”

There is a subreddit on reddit called /r/dailyprogrammer and while they don’t actually post exercises daily, they do sometimes post neat questions that are fun to solve. About a week ago, they posted a problem that I solved with F# that I wanted to share. For the impatient, my full source is available at this fssnip.

The description is as follows:

Unix[2] , the famous multitasking and multi-user operating system, has several standards that defines Unix commands, system calls, subroutines, files, etc. Specifically within Version 7[3] (though this is included in many other Unix standards), there is a game called “arithmetic”. To quote the Man Page[4] :

Arithmetic types out simple arithmetic problems, and waits for an answer to be typed in. If the answer
is correct, it types back “Right!”, and a new problem. If the answer is wrong, it replies “What?”, and
waits for another answer. Every

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