* geesh/lexer.scm (get-parameter-expression): Use '#f' to signal an omitted optional word instead of just omitting the word in the resulting form. * tests/lexer.scm: Add a test for omitted optional words.
* geesh/lexer.scm (*parameter-operators*): Update the names of the operators. * tests/lexer.scm: Fix tests accordingly.
* geesh/lexer.scm: New file. * tests/lexer.scm: New file. * Makefile.am: Add them.