which languages have delimited continuations?
racket
guile ( http://wingolog.org/archives/2011/08/30/the-gnu-extension-language )
which others?
http://stackoverflow.com/questions/16651843/why-does-not-exist-a-primitive-call-with-current-continuations-in-common-lisp
http://dunsmor.com/lisp/onlisp/onlisp_24.html