TICL—A type inference system for Common Lisp

Most current Common Lisp compilers generate more efficient code when supplied with data type information. However, in keeping with standard Lisp programming style, most programmers are reluctant to provide type information; they simply allow the run‐time type system to manage the data types accordingly. To fill this gap, we have designed and implemented a type inference system for Common Lisp (TICL). TICL takes a Lisp program that has been annotated with a few type declarations, adds as many declarations as possible, and produces a type declared program. The compiler can then use this information to generate more efficient code. Measurements indicate that a 20 per cent speed improvement can generally be achieved.