The default behavior

1. builtin procedure including set! and define should be direct style. e.g, + - * / = cons car append drop
2. user defined procedure will be transform to continuation passing style
3. a procedure which accept a high-order procedure as argument should not be builtin, it should aways be transform to CPS. e.g, map filter foldl
4. while a builtin procedure f is treated as an argument (first class function), it will be replace with the CPS version which called f&
5. the expressions inside begin form will be optimized: only the last expression and side-effect expression will exist at last

Other alternatives

• set the variable pure-builtins and side-effect-builtins to empty, then implement all the builtin procedure as CPS, so the whole program including script and interpreter become CPS
  • this choosen make the interpreter looks more easier and stronger, but the program will also be slower, and the output of CPS transfrom will be harder to review
  • racket can not execute the output of CPS transform because racket consider the builtin procedure as DS