The host language
The 1446 book had no host language to explain: its letters were the whole system. gog’s letters live inside four programming languages, and this part is what each language adds.
Everything so far has been the grammar, and the grammar is the same wherever you write it. One engine reads one specification, so the same sentence draws the same plot in every language.
This part holds what the grammar chapters could not say. Some things belong to the language you type in rather than to the grammar, and they cannot be stated once for everybody. A table has to reach data(). A plot has to display in a notebook. And gog’s + has to work beside the operators the language already has. Those are real questions, and answering them in the grammar chapters would answer them wrongly for three readers out of four.
Each of the four has a chapter here (Bezanson et al., 2017; Ecma International, 2025; R Core Team, 2026; Van Rossum & Drake, 2009). The grammar chapters say nothing about any one language, which is what keeps this part separate.
They are ordered R, Python, Julia, JavaScript, and the order has a reason. The first three write the same sentence three times. The operators are identical, and only the column name moves: a bare gdp, then col.gdp, then :gdp. If you have read the R in this book you can read the Python and the Julia already. JavaScript is the one that genuinely reads differently. It is the only one of the four that cannot give +, *, | and / new meanings, so it spells them as words. It is last for that reason, so the pattern the other three share is read first.
The four chapters are also the proof. Every sentence in this book was translated and drawn by every binding. The four produce byte-identical plots and refuse the same sentences in the same words. They differ only where a chapter is about the host language itself.