Nobody actually uses M-expressions. Mathematica and Wolfram use something quite close, but Lisps are almost universally written in S-expressions. There are som

Nobody actually uses M-expressions. Mathematica and Wolfram use something quite close, but Lisps are almost universally written in S-expressions. There are some alternative syntaxes like Sweet expression[1] (t-expression), but they've not found any widespread use. [1]:https://srfi.schemers.org/srfi-110/srfi-110.html https://srfi.schemers.org/srfi-110/srfi-110.html