Briefly describe three "unconventional" compilers-compilers whose purpose is not to prepare a high-level program for execution on a microprocessor.

Two of these unconventional compilers are TEX and Troff, are compilers which translate documents of higher level into commands for either laser printer or typesetters using a text editor. The third one is Query language processor for database system, also considered compilers which translate language for example SQL into primitive operation on files.