Two things about Boo that have left a lasting mark:<p>First, it was the first time I'd seen quasi-quotes, where you can write code that them so converted to AST. Very very lovely dynamic programming. It was so awesome having a static runtime but being able to do multi-phase programming in it, was so much nicer than anything I'd seen in java. Excellent easy to understand macro writing.<p>Second, the boo test cases rocked. Test cases start with a string which is the expected output. Then the rest of the testcase is a short bit of code that outputs. It was so easy to debug & see what was happening, such an elegant frameworkless way to run tests.<p>I used it a couple times commercially at small webdev shops, but had a bunch of personal projects using Boo. Lead author Bamboo got hired by Unity and their (I believe now deprecated?) UnityScript was related/similar I understand, but Boo kept going for a whole. Great docs for the time too. But yeah tapered off.<p>The two techniques I describe, quasi-quotes & tests-as-executable are both visible in this macro testcase, <a href="https://github.com/boo-lang/boo/blob/master/tests/testcases/macros/custom-class-macro-with-properties-and-field.boo">https://github.com/boo-lang/boo/blob/master/tests/testcases/...</a><p>Thanks Bamboo et al!