`1 in [1, 2, 3]` must return (list 1) not true. Root cause: in? compiled
to hs-contains? which returns boolean for scalar items. Fix: new hs-in?
returns filtered list; new in-bool? operator for is/am-in comparison
contexts so those still return boolean. Parser generates in-bool? for
`X is in Y` / `X am in Y`; plain `in` keeps in? → list return.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
giles
67a5f13713