Category: .net

Now, I have some time to write about a couple of questions I have received about F#, and their answers.

1. To get a specific element of a tuple :

If we do not want to create variables for the elements that we are not interested in of a tuple, we can use “_” for all other elements, i.e.:

which is interpreted into the compiler as we see in the FS Interactive window:

2. “namespace” keywords stays as is, and we can have either a module or a type [i.e. C# class] under a namespace. The example would be :
File1: Drink.fs

File2: BeverageCalculator.fs [placed under the Drink.fs if they are in the same project.]

So, we can use everything from the first namespace,
Happy F# days!

After my talk at ldnUG yesterday, I got nice suggestions from Zi Makki, and here is the first one: comparison between F# and C#, especially using LINQ. This subject had been quite popular once in a while, now it is probably my time to focus on this subject. My initial samples are quite common: getting numbers less than 5 from a list, and getting files from a specified directory.

If we want to write this in F#, List.filter will be enough for filter operation, and the List.iter will go through the list, and do any operation/function we define for each item in the list.

The second example if for printing the folder names
With the help of the extension method explained at stackoverflow, here is a better C# code to get the files of a specified path.

private static void Dir(string
{
Directory.GetFiles(path)
.ForEachWithIndex(
(item, idx) => Console.WriteLine(“{0}: {1}”, item, idx));
}
}
public static class ForEachExtensions
{
public static void ForEachWithIndex(this IEnumerable enumerable, Action <T,int> handler)
{
int idx = 0;
foreach (T item in enumerable)
handler(item, idx++);
}
}

And the F# version would be quite simple, as Array.iter is enough to process the array resulting from GetFiles: