A bundle is closed-world — everything it needs is inlined and nothing is
required afterward — so a user defn unreachable from the entry's reference
graph can be dropped. The bundler now computes reachability from main-ns/-main
plus every non-prunable form and drops dead defn/defn- by exact source span
(formatting and reader macros in the surviving code are untouched).
Conservative and sound: only plain defn/defn- are prunable; a defn is kept if
its bare or ns-qualified name appears in any kept form, the closure runs to a
fixpoint, and any use of resolve/ns-resolve/requiring-resolve/find-var/intern/
eval/load-string disables pruning entirely. A parse failure on any file also
falls back to verbatim bundling, so the command stays as robust as a plain
concatenation. defmethod/defrecord/extend bodies are non-prunable and scanned,
so a fn reached only via dynamic dispatch stays live.
New reader/parse-all-spans returns [form start end] byte offsets so the drop
is a verbatim slice, not a re-print.
30-fn library used by a 3-fn entry: bundle 1114 -> 437 bytes (61% smaller, 27
dead fns dropped), output byte-identical.
Co-authored-by: Yogthos <yogthos@gmail.com>
