Rhino (JavaScript on the JVM, originally written by Mozilla) dates back to 1997 and JRuby to 2001. Suffice it to say, dynamic languages have ran on the JVM for

Rhino (JavaScript on the JVM, originally written by Mozilla) dates back to 1997 and JRuby to 2001. Suffice it to say, dynamic languages have ran on the JVM for 20 years. Reflection used to be used to implement dynamic types, but since Java 7 (2011) there's been a JVM instruction, invokedynamic, to explicit support dynamic types.