I wrote an EMA clone in Python recently. I was asked why Python is more productive than Java after the demo. So I collected some proof from Internet.
interpreted vs. compiled is a big productivity win for Python/Ruby
dynamic typing is a big productivity win for Python/Ruby
Java is way faster than Python or Ruby
minimal scaffolding is a big productivity win for Python/Ruby. Makes programming more pleasant not to have to build all the infrastructure.
mostly first class functions a big win for Python/Ruby.
built-in lists/arrays and hashes/dictionaries a big win over Java [] and library based collections.
dynamic code loading in Python/Ruby is a big win. Yes you can do it in Java but again, the cruft. No need for set/get methods in Python
Python has useful constructs Java lacks (Function Objects, Closures, Array and String support, Dictionary Syntax)
Introspection is easier in Python