JewelScript Is No Jewel In The Rough
I decided to look up some non-mainstream languages before moving on the list of Big Popular languages I wanted to try for this new project. I took a look at a few that were outright unsuited, and then found and spent some time looking at JewelScript. Like Pike, JewelScript is an interpreted OO language with a syntax very reminiscent of C/C++.
JewelScript has a lot of nice features. The syntax is familiar, but the addition of coroutines and a ‘var’ type in addition to the static typing make certain classes of application a lot easier to write than C++ does. Unfortunately, JewelScript also seems to be so heavily based on C++ that some of the painful parts of C++ programming are firmly a part of JewelScript programming.
The biggest turn of here is the reference system. In JewelScript, all variables are copy-by-value, just like C++. If you want two variables to refer to the same object, you must declare one of the variables as an explicit reference to the other. That’s not so bad, really, until you get to function arguments. Just like in C++, you end up having to declare many function arguments as references solely for performance reasons, and not because the argument actually needs reference semantics. Also just like C++, that can result in programming errors, so JewelScript has a const reference type, which is a slightly different set of semantics but at least allows you to get decent performance without opening yourself up to programming mistakes.
Really, though, if I felt like declaring 90% of my function parameters with a logically unnecessary const and an equally unnecessary & just to work around the performance problems of the language design, I’d have stuck with C++. JewelScript could potentially fix this behavior with the simple addition of copy-on-write behavior for objects and other “fat” datatypes. That gives the programmer the full performance benefits of a const reference without the overhead of manually declaring const references when copy-by-value semantics were what they wanted in the first place.
JewelScript also lacks a comprehensive standard libary. That’s fine in many respects, but that coupled with a too-C++-like language design make it a poor choice for my project. However, anyone looking for a language to embed in C++ that offers a very familiar syntax, JewelScript might be just what you’re looking for.