This is a web-based interpreter for the excessively principled functional programming language Robin, version 0.8.
Select an example program from the dropdown box and click "Run" to run it. You can also edit the program before running it. Or you could clear the textbox and write an entirely new program there and run it.
You might also want to read the description of the Robin programming language.
Note that the instrinsics defined by the language are available, but the standard libraries are not -- if desired, they would need to be pasted into the textbox above the Robin code that uses them.