Frost supports three different styles of comments:

Line comments

Two hyphens in a row (--) begin a line comment, causing the rest of the line to be ignored:

var x:Int -- initialized in the constructor

Block comments

A hyphen followed by an asterisk (-) begins a block comment, and the opposite sequence (-) ends the block comment:

-* Output the final results
 * Need to do some better formatting in the future

It is legal to nest block comments.

Documentation comments

Three or more equals signs (===) begin and end a documentation comment. Documentation comments are special comments that must appear immediately prior to a class, method, or field, and provide a formal description of the class, method, or field they precede.

Appends a character to the end of the string.

@param c the character to append
method append(c:Char) {

Documentation comments are described in more detail on the documentation comments page. Documentation comments in Frost, unlike in many other languages, are actually part of the language's grammar and thus may not appear anywhere but immediately before a class, method, or field.