Interestingly, the author mentioned both M-expressions ("never implemented") and Mathematica (with a number of interesting links). Mathematics expressions are quite close to https://en.wikipedia.org/wiki/M-expression . Function application is not (f x y) or f[x; y] but f[x, y]. In contrasts, lists in Mathematica are {1,2,3} and thus pretty close to [1;2;3]. This curly bracket list notation is already syntactic sugar, as Lists are actually List[1,2,3] and thus very transparent to how you can represent them in LISP. Mathematica introduces a number of handy abbreviations such as f@x for f[x] or {x,y,z}/.f == Map[f,{x,y,z}] == {f[x],f[y],f[z]}. It even "overloads" the double semicolon symbol ;; basically acting as as in/pre/post-fix "operator", cf. https://reference.wolfram.com/language/ref/Span.html -- the same is true with virtually any symbol such as "==" (Equals) or "+" (Plus).

The Mathematica/Wolfram language could really be a game changer if it was open source.