Teaching C in a Functional Style

The rst introduction to imperative programming for the majority of our students is with C, but fortunately it is preceded by a course on problem solving and program design using the lazy functional language Miranda. C is a diicult language to learn, but by drawing on the skills taught in the Miranda course, notions such as modularity, information hiding, recursion, abstraction, top-down design, functional composition, composite types, and higher order functions can be introduced relatively painlessly. One of the major tasks for programmers is the design and implementation of Abstract Data Types (ADTs). This is made more diicult in C by being based on dynamic data structures coded with pointers. We describe a translation strategy from a Miranda version of an ADT to a C version, which utilises all of the good programming habits developed with Miranda. The translation from Miranda to C allows a wide ranging discussion of many important topics: strict versus non-strict functions, recursive data structures, polymorphism, the importance of typing, pattern matching versus information hiding in ADTs, destructive versus non-destructive assignment, and the trade-oos between understandability and eeciency. This approach to C programming was used in a course at the end of 1993, and the results of a student questionnaire are brieey reported.