Frank Sanchez developed the original language semantics, syntax, parser, compiler and optimizer, database interface, schema binding, intrinsic classes and methods over the Christmas holiday in 1998 and early 1999.
Frans and Dan have focused on implementing the database independent features of the language, and more recently the Java source target code.
Two MUMPS language elements were eliminated initially (M-style blocks and goto label+offset) as they could not be supported within the PSL object scope handling.
This capability was considered to be critical to the ability to generate code that optimized both a MUMPS global database and multiple commercial RDMS's from the same PSL source.
Furthermore, PSL is supported by a modern Eclipse-based development environment, with integrated schema and code management and numerous interactive plug-ins.