Cactoos.Net

.Net port of Java library Cactoos for OOP primitives : https://github.com/yegor256/cactoos
It's a little bit changed to better suit to c#, but the overall oop concept is kept within.
For example in you want to write a String to a text file. How it looks in java:

new LengthOfInput(
  new TeeInput(
    new BytesAsInput(
      new TextAsBytes(
        new StringAsText(
          "Hello, world!"
        )
      )
    ),
    new FileAsOutput(
      new File("/tmp/hello.txt")
    )
  )
).value(); // happens here

And how it looks in Cactoos.Net:

 new Output(
     new StringInput("hello cactoos"),
     new PathOutput("file2.txt", FileMode.Truncate)
 ).Count(); //happens here

Read numbers from text file and count a sum of them:

new Output(
    new DoubleText(
         new DoubleSum(
              new ParsedDoubles(
                  new Lines(
                      new InputText(
                          new PathInput(@"C:\Users\user\Desktop\apteka.txt"),
                          Encoding.Default
                      )
                  )
              )
         )
    ),
    new ConsoleOutput()
).Count(); //"trigger" the code to run 

Some words about Output.Output is IEnumerable<byte>. It wraps two sources of data(Stream, IEnumerable<byte>, IInput) and writes first data source to second(Stream or IOutput) just like a TeeInput in the original library as the iteration happens.
I prefer to use C# LINQ Count() instead of LenghtOfInput for brevity. The same is true about Input, it implements IEnumerable<byte>
and allows to iterate over Stream. Contact me in Telegram: https://t.me/Andriy_Shevchenko.