Version 1.4.3 of Parsons’s Discount is out, and with it, Plan 9 support becomes part of the official distribution. The Plan9 subdirectory added to the source contains a mkfile that drives Discount’s own scripts and APE’s make(1) to build the code, optionally copying the results to locations appropriate for system-wide use. Man(6)-format manual pages are also included for the markdown tool and syntax.
To build it, fetch the latest source archive from the Discount site (currently 1.4.3), extract it, then:
% cd discount-1.4.3/Plan9
% mk config && mk
% ../markdown -V
markdown: discount 1.4.3
Configuration options can be set in a CONFIG variable to mk config. Install the binaries and/or manual pages with a few other mk(1) targets; see mkfile and README for details.