The examples in this tutorial have used the standard Haskell format. In the standard
format, comments are indicated with a double dash to their left. All comments in the
examples are end-of-line comments, which means that everything following a double
dash on a line is a comment. You may also create multi-line comments by enclosing
blocks in the pair "{-" and "-}". Standard Haskell files should be named with the .hs
extension.