This page contains FTL library, basics of FTL in individual examples, and some actual examples.
Lastly there is write your own program panel where you can either copy from example or write your own FTL program.
Here is the character set for operator definition. You can define any operator using either a single character or mltiple ones from this set, except "->", which is preserved. Simply copy from below when you need to define your own operator: