DrScheme: A Pedagogic Programming Environment for Scheme

Teaching introductory computing courses with Scheme el evates the intellectual level of the course and thus makes the subject more appealing to students with scienti c interests Unfortunately the poor quality of the available programming environments negates many of the pedagogic advantages To overcome this problem we have devel oped DrScheme a comprehensive programming environment for Scheme It fully integrates a graphics enriched editor a multi lingual parser that can process a hierarchy of syntactically restrictive variants of Scheme a functional read eval print loop and an algebraically sensible printer The environment catches the typical syntactic mistakes of beginners and pinpoints the exact source location of run time exceptions DrScheme also provides an algebraic stepper a syntax checker and a static debugger The rst reduces Scheme programs including programs with assignment and control e ects to values and e ects The tool is useful for explaining the semantics of linguistic facilities and for studying the behavior of small programs The syntax checker annotates programs with font and color changes based on the syntactic structure of the pro gram It also draws arrows on demand that point from bound to binding occurrences of identi ers The static debugger roughly speaking pro vides a type inference system with explanatory capabilities Preliminary experience with the environment shows that Rice University students nd it helpful and that they greatly prefer it to shell or Emacs based systems