LaTeX3 (https://www.latex-project.org/latex3 https://www.latex-project.org/latex3) is in some sense meant to be just that. (The author's Tectonic project appar

LaTeX3 (https://www.latex-project.org/latex3 https://www.latex-project.org/latex3) is in some sense meant to be just that. (The author's Tectonic project apparently also aims to do this: see https://newton.cx/~peter/2024/the-new-latex https://newton.cx/~peter/2024/the-new-latex .)