It's still in the 0th major version, such changes are expected until 1.0. I indeed wouldn't recommend using Crystal for anything serious until the language stabilizes.
I think this is a good strategy if you want to end up with a good core language with a lot of polish.
Re:Crystal 0.31
by paulcsmith on Monday September 23, 2019 @09:26PM
(#21055570)
Totally agree. If this happened post 1.0 I’d be concerned. But pre 1.0 this is what I’d expect and want. Polish things up because afterward you can’t!
(Or you can and you get the Python 3 debacle for a decade.)
There is potential in Crystal but the most terrifying thing about using it right now is the breaking changes.
How often is it that Crystal has to continue to keep doing breaking changes on every release? Everytime I read a new changelog, I am put off of updating due to the number of changes required to compile with a new version. There are 8 breaking changes in this release which is enough to put some people off of learning the language. It is now equivalent to Swift 3 at this point: No source-compatibility, some initial Windows support and experimental multi-threading.
Other than this, in terms of its speed and Ruby-like syntax, Crystal completely blows all other languages out of the ocean. And it is on par with C/C++/Rust and Zig.