Test at https://www.tutorialspoint.com/execute_smalltalk_online.php.

Smalltalk was the first ever really object-oriented language. Is was created by Alan Kay, who also created the paradigm itself.

In this script, the idea is simple: we send a message to the ifTrue object. Based on that message, the object will decide whether or not to execute the function passed. That is the basic ideas in object oriented languages: objects that communicate through message passing!

Further reading:

https://dl.acm.org/citation.cfm?id=273 http://wiki.c2.com/?AlanKaysDefinitionOfObjectOriented