After reading through this thread, perhaps this piece of missing information for @abhi18av (and anyone else interested) is this:
If you are asking “But only - why femtolisp in particular?” the answer would be, as I understand (see this), Jeff Bezanson wrote femtolisp before beginning to work on Julia. So it was the right tool for the right person at the right time, and there has been no strong need or effort to change since.