I've had a chance to work on a fairly large chunk of Python at this point and have decided that Python (like Perl) is completely untenable at scale. <rant><rave><drool> but wait! I have reasons! Programmers spend most of their time reading code. We read massive amounts of code. After we read massive amounts of code we write one... or change one... To make a change to a piece of code you first have to understand what it does and how it interacts with the system around it. Then we start reading massive amounts of code again. Anything you can do to minimize the amount of code a programmer has to understand to make a change becomes a huge gain in productivity. Duck typing causes the amount of code you need to read to make a change to grow very large. For example lets look at two functions, one in C++ and one in Python. First in C++ int function(type1 arg1, type2 arg2) { return arg1->method(arg2); } In this function we know that it takes two typ