An effect system is an extension of a type system where a function type encodes inputs, outputs and effects.
The article mentions that they handwaved all the typing stuff (when you do that, effect handlers are more like delimited continuations). But the types are important. If a function doesn't tell you it's effects, how do you know you have to handle them? You'd have to read the whole call graph. That's why exceptions suck.
I don't worry too much about HTML output still being WIP. Even if TeX had a massive head start, Typst has a good development speed, and a little bit of slope makes up for a lot of y-intercept.
https://en.wikipedia.org/wiki/Pierre_Menard,_Author_of_the_Q...