your data is trapped inside the box that is your program. some languages try to make the box bigger—interop between Java, Kotlin, and Clojure is comparatively quite easy because they all run on the JVM. but at the end of the day the JVM is another box; getting a non-JVM language to talk to it is hard. some languages try to make the box extensible—LISPs, and especially Racket, try to make it very easy to build new languages inside the box. in my next post, i will discuss how we can escape this box.