The files that should be here are doled out during the course of the semester. They can be found in the RCS directory below (which isn't accessible to students). Use the RCS command co filename.scm to extract the latest copy of a file named filename.scm. Use the RCS command co -l filename.scm to edit it. See the manual pages for rcs, co, ci, rlog, rcsdiff, for more details. The file char-parser-extended.scm adds some syntax to the character-based language that is useful for various exercises (such as for loops). See EOPL chapter 11 for details on how the scanner and parser work.