Io
Prototype-based, purely message-passing language — minimal syntax, everything is a message send to an object.
dynamic
interpreted
since 2002
oopprototype-basedconcurrent
Io was designed as a thought experiment in minimalism — the entire language is built from objects that pass messages to each other. There are no classes, only prototypes. Coroutines and actors are built in. Steve Dekorte created Io as an exploration of the smallest syntax that could support a complete programming model, influencing several later languages.