[oscardssmith]

One other really good example is BLAS. Since it is a C/Fortran library you have 26 different functions for matrix multiply depending on the type of matrix (and at least that many for matrix vector multiply). In Julia, you just have * which will do the right thing no matter what. In languages without multiple dispatch, any code that wants to do a matrix multiply will either have to be copied and pasted 25 times for each input type, or will have 50 lines of code to branch on the input type. Multiple dispatch makes all of that pain go away. You just use * and you get the most specific method available.