Ignoring the Crystal issue that others already answered, why didn't Julia developers instead create a kick-ass JIT for Python or R? And the answer to that is t

Ignoring the Crystal issue that others already answered, why didn't Julia developers instead create a kick-ass JIT for Python or R? And the answer to that is that the semantics of the language were designed from the start for efficient JIT'ing. Thanks to the language design, Julia can get close to C performance with a comparatively simple JIT approach (resolve types, compile a function statically with LLVM just like C, then use multiple dispatch to select the right function at runtime (simplified, yes, but roughly like this)). Compare this with all the tracing JIT heroics that Javascript implementations or PyPy pull, while still getting performance far from what Julia achieves.