Functional Programming Patterns

If you're new to functional programming (like me), you'll quickly find a number of useful patterns that you can apply to your everyday coding tasks. Take the following task as an example: we have a FeatureCursor and we would like to repeat a certain action for every Feature in the Cursor. In C#, it would look something like this:

IFeature feature = cursor.NextFeature();
while (feature != null)
{
    // Do something with the feature
    Console.WriteLine(feature.OID);
    feature = cursor.NextFeature();
}

This is a common pattern in ArcObjects. How can we express this pattern in F# while allowing for flexibility in the action that we wish to perform?

let forAll (f : IFeature -> unit) (cursor : IFeatureCursor) =
    let mutable feature = cursor.NextFeature()
    while feature <> null do
        // Do something with the feature
        f feature
        feature <- cursor.NextFeature()

We can pass any function that we want to so long as it takes an IFeature and returns unit:

forAll (fun feature -> Console.WriteLine(feature.OID)) cursor

You could write a ForAll function in C# but it just wouldn't feel as natural, would it?