Miranda released as free software
You've at least heard of (if not used) a programming language heavily inspired by Miranda: Haskell. A lot of things about Miranda were really interesting; it reflects modern languages in some ways, but looks completely foreign in other ways. Like Haskell, whitespace was significant; unlike Haskell, it was fast. Really fast.<p>It was one of the pioneering purely-functional languages, but seems to have been mostly forgotten. That's unfortunate, because in many ways it still is superior to its successors. Their fault for keeping it proprietary for so long, really.