MockBasic was originally written using the MS-BASIC interpreter. It even built its own resource files from scratch, using a "swap fork" utility to make the file be a real resource file. Before I got each of them complete enough to compile to native 68000 code, the compiler was taking half an hour to compile, then the linker was taking half an hour to link.
I actually made a few projects using this compiler. The most useful was a 68000 disassembler. I already had an MS-BASIC version, but it was slow and cumbersome and could only disassemble stuff that was already in memory. This would later get re-written in Pascal.
I also wrote a disk copying/formatting utility called Monster Copy, which took advantage of my recent Levco MonsterMac 2 megabyte RAM upgrade to read an entire 800k floppy disk into memory for making copies, and a version of the game Black Box.
My need for MockBasic ended when a friend gave me a copy of TML Pascal (which sold for $99) to work on a project for him. I can't even remember what that project was supposed to be, but this is what put me on the path of programming in Pascal, rather than C.
MockBasic 1.8 source code
MockLinker 1.8 source code
MockBasic documentation
StuffIt archive of MockBasic files