Eiffel and Sather - A Comparison

The Common Lisp Object System defines a powerful and flexible type system that builds on more than fifteen years of experience with object-oriented programming. Most current implementations include a comfortable suite of Lisp support tools in cluding an Emacs Lisp editor, an interpreter, an incremental compiler, a debugger, and an inspector that together promote rapid prototyping and design. What else might one want from a system? We argue that static typing yields earlier error detec tion, greater robustness, and higher efficiency and that greater simplicity and more orthogonality in the language constructs leads to a shorter learning curve and more in tuitive programming. These elements can be found in Eiffel and a new object-oriented language, Sather, that we are developing at leS!. Language simplicity and static typ ing are not for free,·though. Programmers have to pay with loss of polymorphism and flexibility in prototyping. We give a short comparison of CLOS, Eiffel and Sather, addressing both language and environment issues. The different approaches taken by the languages described in this paper have evolved to fulfill different needs. While we have only touched on the essential differ ences, we hope that this discussion will be helpful in understanding the advantages and disadvantages of each language