-- `xs.(expr)` (parenthesised expression after `.`) is not valid ilo syntax,
-- but it's a common reach for variable-position indexing when the index is a
-- computed expression rather than a bare name. PR #298 desugars `xs.i` to
-- `at xs i` when `i` is a bound variable, so the natural extension to
-- `xs.(i+1)` is a reasonable guess, hence the friendly parser hint
-- pointing at `at xs (expr)` or the bind-first idiom.
--
-- This example demonstrates the two correct shapes the hint suggests.
-- Shape 1: `at xs (expr)` — the direct form. Three tokens plus the parens.
plus1 xs:L n i:n>n;at xs (+i 1)
-- Shape 2: bind to a name first, then use `xs.i` (PR #298 desugar path).
plus1bind xs:L n i:n>n;j=+i 1;xs.j
-- run: plus1 [10,20,30] 0
-- out: 20
-- run: plus1 [10,20,30] 1
-- out: 30
-- run: plus1bind [10,20,30] 0
-- out: 20
-- run: plus1bind [10,20,30] 1
-- out: 30