Doing more with code lines

There are many ways of producing web-pages. At one extreme you can create the HTML for a webpage with a text-editor. At the other you can produce the webpage by running a program. Grobbler is a compromise between the two. It has a small number of facilities built in, to which you can add by putting a file called defs in your source directory. These can be used by any of the source-files in it. That means that you can personalize Grobbler toward your own brand of markdown, in one direction, or simply not use code lines, in the other.
Under the bonnet, the code lines constitute a Lua program. The ordinary lines that start with a minus sign can access global variables from the program using the dollar-sign prefix. A code line
 date = os.getenv "Sys$Date"
allows you to insert the current date into a web-page, for example. Looping structures, functions, I/O are all available if you should need them.