Presentation STklos (pronounced /ˈɛs.’ti.kl’ɔss/) is a free Scheme system mostly compliant with the language features defined in R⁷RS small. The aim of this implementation is to be fast as well as light. The implementation is based on an ad-hoc Virtual Machine. The salient points of STklos are: an efficient and powerful object system based on CLOS (Common Lisp Object System) providing Multiple Inh