-- setunion / setinter / setdiff — set operations on lists.
-- Inputs are deduped, output is sorted (stringwise on a type-prefixed key)
-- so results are deterministic across runs and engines.
--
-- Element types must be text, number, or bool (same restriction as uniqby).
-- Numbers and texts live in separate domains: 1 and "1" never collapse.
--
-- Caveat — sort is *lexicographic* on the stringified key, not numeric. So
-- a list like [10, 2] sorts as [10, 2] (because "n:10" < "n:2" in string
-- order), not the numerically-intuitive [2, 10]. If you need numeric order,
-- sort the result yourself with `srt` after the set op.
-- Tags shared between two posts: which subjects do they have in common?
shared a:L t b:L t>L t;setinter a b
-- run: shared ["rust","vm","jit","types"] ["types","jit","gc","async"]
-- out: [jit, types]