That was an example, I was trying to offer chrisseaton a different notion of "similarity".

Another example: if 0% of Ruby code works in Crystal unmodified, but for 90% of code the transformation was extremely simple and mechanical like using curly braces {...} instead of begin...end and prepending $ to all variable names like Bash and PHP, they would still feel extremely similar in practice, albeit obviously less similar than the above example.

By contrast, Java and JavaScript are widely described as having very similar syntax, but it is rare to translate code from one to the other without require fundamental rethinking, because the relationship between JS objects, functions, and prototypes is so different from between Java objects, methods, and classes.

Depends on how you count. On a application level, no. On a class level, also no. On a method level, no but we are getting close. On a row level, possibly. On a token level, definitely.

> 90% of your Ruby code will absolutely not work in Crystal unmodified.

Don't nail me on exact 90%, but for me it does. Nothing rails related though. Good example: https://news.ycombinator.com/item?id=23437035

However, I agree that the fundamentals/underlyings are very different. It's far from being like a python 2 to 3 migration.