MEdit is a library implementing the underlying features of a text editor. It is intended to be useful both for implementing a command-line editor and for a GUI editor with the use of an external toolkit.
MEdit is written in a mixture of Mercury and Assembly (with a small amount of glue in C). Mercury is a purely declarative, pure functional logic langauge. Assembly is assembly. I chose Mercury because a number of operations can be expressed nicely with pure declarative syntax, such as text insertion and deletion, undo/redo, and cursor management. But functional languages tend to either be inefficient or cumbersome when it comes to memory management, and so I decided to perform the basic memory management (particularly with regards to text buffers) in a native language. I chose Assembly for two reasons. One, for the fun, and two because only low level languages seem to really be suited to the task.
It's not ready :) You can try it out by building it first. You will need the Mercury compiler, at least version 14 (although there is a bug in the HLC grade for MMC 14 that MEdit hits), and yasm or nasm. Build the library, then check out the *.mh files for the API.
I'll add doxygen or pandoc someday. But it's not in a stable state to meaningfully document yet.