Deck is (was?) an experimental programming language I designed and implemented some years back. The idea was to put a conventional syntax on top of a Lisp-like language in a very transparent way so that you get all of the reflective power of Lisp while still having a human-friendly syntax.
This:
a := b + 3*c
would transform into this:
(:= a (* 3 c))
so you could apply macros and other code transformations onto it, but the transformation made sense; you could write an infix expression and have a pretty good idea of what came out.
Unfortunately, it ended up being the worst of both worlds. The syntax stopped being easy for complex code while obscuring the underlying tree structure.
Still, there are some pretty good ideas there. I may take another run at it some time in the future.
Links: