#typst PSA:
Typst is actually three languages in a trench coat:
* The default, a markdown-like language.
* A programming language, where you can do... well, programming stuff: define variables and functions, compute things, ...
* A language just for describing math expressions to be typeset (like LaTeX's math mode, but the syntax is different)
You can call constructs from the programming language (and consequently, enter "programming language mode") by prepending them with a #: `#let a = 3`, `#someFunction(someValue)`, etc.
Conversely, you can define content in the markdown-like language from within the programming language by enclosing it in square brackets: `let title = [= My Title]`
You can write expressions in the math language by enclosing them in between dollar signs: `$1/2 = 0.5$`
...yes, if you knew it already, it's obvious. But I didn't, and this caused me a couple headaches back when I was learning Typst.
