retroforth/doc/book/general/retro-unu

# Unu: Simple, Literate Source Files

Retro is written in a literate style. Most of the sources
are in a format called Unu. This allows easy mixing of
commentary and code blocks, making it simple to document
the code.

As an example,

    # Determine The Average Word Name Length

    To determine the average length of a word name two values
    are needed. First, the total length of all names in the
    Dictionary:

    ~~~
    #0 [ d:name s:length + ] d:for-each
    ~~~

    And then the number of words in the Dictionary:

    ~~~
    #0 [ drop n:inc ] d:for-each
    ~~~

    With these, a simple division is all that's left.

    ~~~
    /
    ~~~

    Finally, display the results:


    ~~~
    'Average_name_length:_%n\n s:format s:put
    ~~~

This illustrates the format. Only code in the fenced blocks
(between \~~~ pairs) get extracted and run.

(Note: this only applies to source files; fences are not used
when entering code interactively).

## On The Name

The name Unu comes from the Maori language, where it means:

    (verb) (-hia) pull out, withdraw, draw out, extract.
    Taken from https://maoridictionary.co.nz/