Introduction

Scientific computing has long suffered a two-language problem: prototype in Python or MATLAB, then rewrite the slow parts in C or Fortran. Julia, released in 2012, was built to end that split — a language that reads like a scripting language and runs like a compiled one. It powers climate models, drug discovery, and the world's largest telescopes, and its secret is a design choice most languages never make: multiple dispatch, where the function that runs depends on the types of all its arguments.

Multiple dispatch and just-in-time compilation

Julia's model rests on a few distinctive ideas:

Multiple dispatch — define one function name with many methods, and Julia picks the right one based on every argument's type, not just the first.…