#!/usr/bin/env retro

Unu

unu (verb) (-hia) pull out, withdraw, draw out, extract.

Unu is a tool for extracting fenced code blocks from Markdown documents.

I always found documenting my projects annoying. Eventually I decided to start mixing the code and commentary using Markdown. Unu is the tool I use to extract the sources from the original files. I've found that this makes it easier for me to keep the commentary up to date, and has lead to better commented code.

~~~{{ 
  'Fenced var 
  :toggle-fence @Fenced not !Fenced ; 
  :fenced? (-f) @Fenced ; 
  :handle-line (s-) 
    fenced? [ over call ] [ drop ] choose ; 
---reveal--- 
  :unu (sq-) 
    swap [ dup '~~~ s:eq? 
           [ drop toggle-fence ] 
           [ handle-line       ] choose 
         ] file:for-each-line drop ; 
}} 
 
#0 script:get-argument [ s:put nl ] unu 
~~~

Commentary

The basic process for this is simple:

• Read a line from a file
• If the line is a fence (~~~) boundary, toggle the fence state
• If not a fence boundary and the fence state is true process the
line • Repeat until done

The C implementation displays the lines to stdout. For this I decided that the unu word should be a combinator. This makes it easy to use as the basis for other tools. (See example/retro-muri.forth as a demonstration of this)