> Font families seem like an incredible idea that I'm surprised nobody's done before
Oh this has been done for decades. Metafont (by the inimitable Don Knuth) let you describe glyphs as toolpaths in code. You could have as many parameters as you wanted; I've seen examples where a sans-serif is smoothly swept into a serif.
Metafont never got adopted as much as I would have hoped; the lack of a graphical editor and some impedance mismatch with OpenType probably prevented its wider adoption.
there are still people using it---a few examples of being used in Malayalam: https://typedrawers.com/discussion/4912/metafont-in-2023-nup... (the paper linked there has more information); the comments have work by another group which was presented at the TeX Users Group conference a few months ago.
Also, according to Don Knuth himself: "Asking an artist to become enough of a mathematician to understand how to write a font with 60 parameters is too much".
More like, asking a mathematician to become enough of a typographer to design a font that looks clean and consistent and actually aids reading is too much.
Real typographers know that the Computer Modern family is garbage.
Who are these typographers, any examples? Considering:
• The design of Computer Modern was based on Monotype Modern 8A, which was made by a "real typographer" for Monotype corporation and used for decades in several textbooks by Addison-Wesley, including the first editions of TAOCP volumes 1–3 (and 2nd ed of vol 1).
• Knuth got close feedback on the font specimens at various steps of the process (and incorporated the suggestions) from many of the world's top font designers, in particular Hermann Zapf, Matthew Carter, Richard Southall, Charles Bigelow and Kris Holmes, who between them are behind such typefaces as Palatino, Optima, Verdana, Georgia, and Lucida. (Zapf and Southall visited Knuth at Stanford and spent weeks working closely with him on the fonts.) I imagine they wouldn't have spent so much time on it if they thought it was "garbage".
• Of course, Computer Modern, and Monotype Modern before it, are (intentionally) boring "workhorse" fonts for textbooks and won't win any points for being stylish or novel or a work of typographic genius — but within that category, CM is AFAICT something close to the best possible rendering of the basic design, very far from "garbage". I'm curious who thinks otherwise. (I've read a few reviews from typographers and no one said the font was bad; one I remember praised the even "texture" of the page, though that was more a result of TeX's Knuth–Plass line-breaking rather than the font itself.)
• (There is also a well-known issue with CM's appearance on low-resolution devices like computer screens rather than print, and especially the "spindly" appearance of the vector font that usually ends up getting used today if one asks for Computer Modern—see my answer at https://tex.stackexchange.com/a/361722 and links in the comments on it—but those have nothing to do with Knuth's design; in fact Knuth personally still uses the Metafont-generated bitmap fonts unlike everyone else. And there are now "newcomputermodern" and "mlmodern" to remedy this.)
Oh this has been done for decades. Metafont (by the inimitable Don Knuth) let you describe glyphs as toolpaths in code. You could have as many parameters as you wanted; I've seen examples where a sans-serif is smoothly swept into a serif.
Metafont never got adopted as much as I would have hoped; the lack of a graphical editor and some impedance mismatch with OpenType probably prevented its wider adoption.