Native WordsWhat's this?
Hover on a word and you will see a description of it. Moreover, you are shown the word's stack effect, which tells how the word affects the stack. Here's an example:
( x y -- y x )
Before "--" is elements that are taken from the stack (when word is used) and after "--" are the elements that are put back. Note that the names in stack effect are only descriptive.
Factor requires you to write stack effects for your own words but this enviroment does not for ease-of-use.
Also, by hovering on word, you get an example of the use in the bottom right corner. Click on the "Step trough..." button to see the example step-by-step.
Custom wordsWhat's this? Save
The syntax is:
: wordname <sequence of valid symbols> ;
An example : double 2 * ; which would define a word named "double" that puts number 2 on the stack and then uses multiplication word named *.
Click on "Custom words" headline and you will get all of the custom words as a string in the input. By executing that string on another session, you define all of the custom words in one go.
Alternatively, you can save them locally, if your browser supports it. Try it out!