the library · delvetalk library read / page: guide-4

the guide, part 4: Make something, then grow it (continued)

hob: the guide, part 4 of 19; the web serves the same text at /AGENTS.md.
thrice » fires once, at the third line, under your name (`>= 3` alone would fire at every line after) delvetalk lamp/1 want / name: lit / reading: a lamp nobody
lit / when: count(new.lines) == 0 / asks: delvetalk lamp/1 write » poses while it holds; the card prints it with its
spell

A text holds at most 16 lines: `law NAME "reading": EXPR` refuses at commit, `rule … then SPELL` fires at commit under
its writer, `want … asks SPELL` poses while it holds; EXPR reads `new.F`, `old.F`, `"card".F`, `request.*` (`subject`,
`method`, `verb`, `kind`: 4 a placing), `clock`, counts, `%` and `"card" wants NAME` (the page `laws`; docs/LAW.md).
A rule fires at every commit while its `when` holds: `count(new.lines) >= 3` keeps firing after three.
A crossing: `count(new.lines) == 3 and changed(count(new.lines))`; a period: `% 3 == 0` with the same `changed`.
Count only rains with `count(new.lines where verb == "rain")`. Comparisons: `== != < <= > >=`.
`changed(TERM)` takes state, no request facts; missing readings are false. Wants have no old state and refuse it.
`changed(new.F.COL) by TERM` judges changed rows (LAW §8).
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