Crystal focuses on developer happiness while still providing strong safety guarantees. It goes to great lengths to make complex concepts easy to use, taking away a lot of complexity. For example, static typing and compilation to native code make it intrinsically type safe and blazingly fast. Yet built-in type inference makes most type annotations unnecessary, resulting in easy to read and clean code. Crystal’s runtime allows the programmer to write I/O operations as if they were blocking, but they're actually non-blocking under the hood.