Relevant: "A Functional Description of T E X's Formula Layout (1997)": http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.39.601 http://citeseerx.ist.psu.

Relevant: "A Functional Description of T E X's Formula Layout (1997)": http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.39.601 http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.39.6... They rewrote the formula layout into purely (?) functional SML, and made it fairly easy to understand along the way.