[Mark Smith]'s runtime [procedure] editor, PED
[http://www.7bsoftware.com/software/ped.tcl], 
is a sort of [dynamic debugger] which developers
use to make changes to programs while running.
At least occasionally, [Richard Hipp] cites PED as 
an example component for his vision of "Database
as Program", where all source-code is fully versioned
in a single-file data manager such as [Metakit] or
[sqlite].  This leads to such thoughts as a "self-hosting
development environment" easily smart enough to 
correct both the currently running process and a more
persistent source image.  Other natural fall-outs are
"user-editable help screens", built-in versioning,
more efficiently-reclaimed memory,