How Julia works

(You can safely skip this section on a first reading.)

Julia works with an LLVM JIT compiler framework that is used for just-in-time generation of machine code. The first time you run a Julia function, it is parsed and the types are inferred. Then, LLVM code is generated by the JIT (just-in-time) compiler, which is then optimized and compiled down to native code. The second time you run a Julia function, the native code already generated is called. This is the reason why, the second time you call a function with arguments of a specific type, it takes much less time to run than the first time (keep this in mind when doing benchmarks of Julia code). This generated code can be inspected. Suppose, for example, we have defined a f(x) = 2x + 5 function in a REPL session. Julia responds with the message, f (generic function with 1 method); the code is dynamic because we didn't have to specify the type of x or f. Functions are by default generic because they are ready to work...