flan/test/programs/macro-destructure-arity.flan
Joseph Ferano 69646e534e A macro's parameter list, and one grammar for it
(defmacro do-grid [[r rows c cols] & body] ...) — positional names, a [ ]
pattern wherever an argument is a vector, and & for the tail. The reading of
the list lives in Expand, below both sides that need it: Parse turns it into
the bindings a macro body opens with, and Macro checks a call against the same
reading before expanding it, so arity and shape are refused with the call's own
location rather than with the Loc.from_macro stamp every node of an expansion
carries.

The breaking half: [args] used to bind the whole argument list and now binds
the first argument. The whole list is [& args], and every defmacro in the tree
— prelude, vendor, tests, the elisp fixtures — was migrated to it. One grammar,
not a legacy mode.
2026-09-20 18:18:24 +07:00

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;;;; A vector of the wrong length for the pattern. Four names, three forms.
(defmacro do-grid [[r rows c cols] & body]
`(dotimes [~r ~rows] (dotimes [~c ~cols] ~@body)))
(defn main [] i32
(do-grid [i 2 j] (println "never"))
0)