Fat comma (also termed hash rocket in Ruby and a fat arrow in JavaScript) refers to the "=>" operator present in some programming languages. It is primarily associated with PHP, Ruby and Perlprogramming languages, which use it to declare hashes. Using a fat comma to bind key-value pairs in a hash, instead of using a comma, is considered an example of good idiomatic Perl. In CoffeeScript, the fat comma is used to declare a function that is bound to this.〔(【引用サイトリンク】first=Jeremy )〕 # a typical, idiomatic use of the fat comma in Perl my %newHash = ( first_name => "Tom", last_name => "Auger" );