Ask HN: Have you ever used a language in production before the lang reached v1?

Some developers (possibly most?) won't touch a language for production use until it reaches a version 1.0? Have you every used (or are using) a programming language not yet at version 1.0? What was the reason for using the pre-1.0 version of the language? What made you confident in using the language despite it's pre-1.0 state? Did you run into problems? Or was the experience fine?