Compared to a lot of C++ and other compile time polymorphism, the error messages are consistently excellent, if sometimes long, and some of this is due to the s

Compared to a lot of C++ and other compile time polymorphism, the error messages are consistently excellent, if sometimes long, and some of this is due to the simplicity of traits. I am also extremely fond of pattern matching and algebraic data types (first class tagged unions). It is a style of data modeling borrowed from ML/Haskell and is quite distinct from OOP. The key distinction is that by making a datatype with multiple variants closed to extension, you can clearly see and handle all possible cases for a particular purpose (with checking from the compiler) which is often more natural then having fragments of implementation across many child classes.