Icon was also produced by the same man, Ralph Griswold. And it has inspired a newer incarnation, Unicon. I imagine each would also be pretty good at string processing.
First started programming in MIIS (relative to MUMPS) in late 1981. And have continued to use MUMPS/M/MSM/DSM/Cache for most of the intervening years with 4 years off for Fortran and a year or two for COBOL.
Most of the work has been with medical information systems, although the first job entailed a library information system. One of the few languages I knew of which could make a PC-AT into a multi-user machine. It also enabled a clinic to move from a PDP to a 386 and to no longer have to relegate financial batch jobs to off hours.