[texhax] Any crazy math formulas for testing a TeX language interpreter

Douglas McKenna doug at mathemaesthetics.com
Wed Jan 13 20:04:24 CET 2016

Joseph Wright wrote -

> In any case, some form of expandable comparison that ignores catcodes is
> very useful, and it's essential to use expl3 (we found some years ago
> that this was the one post-e-TeX primitive that was vital in all cases,
> though as David notes once you get to dealing with Unicode then some
> ability to generate tokens across the full range is also needed).

So … something like a three-way switch, e.g.,

\ifstrcmp <char token list> <char token list>
     <case 0 for less than> \or
     <case 1 for equal> \or
     <case 2 for greater than>


Or a two-way explicit comparison of some kind, e.g., 

\ifstrcmp { <char token list> } < = > { <char token list> }


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