Expression

Template expression is a subject that comes up a lot.  It's how you create a document, a document being a more-or-less structured chunk of text.

In its more restricted form, template expression takes a map of values and writes them into a tagged template to create a document.  As you increase the complexity of the template language, you approach natural language and you start talking about structured text or structured documents.

I think of this as "expression" in general of a data structure of arbitrary complexity.  There's a sliding scale there from simple stringification to serialization to templates to structured text that probably should be explicitly represented in this procedure language - not least because the preparation of documents comes up in business so very often.

(In a sense, if we take binary data to be a kind of document, then compilers are a form of expression as well. That's kind of an interesting notion.)

That's your disjoint thought stream for the day.  Back to work, you!