[gumby]

Logo basically was Lisp -- a small parser on top of MACLISP.

There were some later small implementations (e.g. for the Apple II) that were written from scratch and didn't need to implement all of Lisp (e.g. lambda, plists, etc).

[mst]

Does that make logo the sole truly successful form of m-expressions?

[lonelappde]

No, because m+expressions are syntax and logo has a different syntax, and because Mathematica is a successful use of something much closer to m-expressions.