defn: support the attr-map form

(defn name docstring? {:k v} arglists...) and the multi-arity name+attr-map
now merge the attr-map into the var metadata like Clojure — jolt was parsing
the map out of the body and discarding it. The metadata (the name's own ^{},
the attr-map, and the docstring as :doc) is attached to the def name symbol,
which analyze-def reads and evaluates. defn is in the earliest tier, so the
macro uses only conj/assoc/meta/with-meta (not merge/last). The rare trailing
attr-map (after the last arity) is not yet handled. Fixes hiccup's defelem
meta + honeysql docstring tests.

jolt-core/clojure/core/00-syntax.clj

@@ -377,21 +377,31 @@
 ;; vector + body or a sequence of ([params] body) clauses, so no arity branching is
 ;; needed. (map? is true for symbol forms too, so guard the attr-map with symbol?.)
 ;; Defined before fresh-sym below, which is a defn-.
+;; defn lives in the earliest tier, so its macro body may only use primitives
+;; available before the seq/coll tiers — conj (which merges a map onto a map),
+;; assoc, meta, with-meta — not merge/last/butlast.
 (defmacro defn [fn-name & body]
   (let [docstring (when (and (seq body) (string? (first body))) (first body))
         body (if docstring (rest body) body)
-        body (if (and (seq body) (map? (first body)) (not (symbol? (first body))))
+        ;; the attr-map after an optional docstring (or after the name) — its keys
-               (rest body) body)
+        ;; merge into the var metadata, like Clojure. A map in the first arity
-        ;; ^{:map} metadata on the name reads as a (with-meta sym …) form, not an
+        ;; position is the attr-map only when more body follows (else it is a lone
-        ;; annotated symbol. def attaches the metadata, but fn needs a
+        ;; map body) and is never a symbol (a name carries its meta as a form).
-        ;; bare symbol, so unwrap it for the fn name.
+        attr-map (when (and (seq body) (next body) (map? (first body)) (not (symbol? (first body))))
-        fn-only-name (if (symbol? fn-name) fn-name (first (rest fn-name)))]
+                   (first body))
-    ;; pass the name through to fn: the compiled fn's host name carries it,
+        body (if attr-map (rest body) body)
-    ;; so stack traces read app.deep/level3 instead of a gensym. A leading
+        ;; the bare name + any ^{:map} metadata the reader attached to it.
-    ;; docstring rides the def's docstring slot so (:doc (meta #'f)) is set.
+        fn-only-name (if (symbol? fn-name) fn-name (first (rest fn-name)))
-    (if docstring
+        name-meta (meta fn-only-name)
-      `(def ~fn-name ~docstring (fn ~fn-only-name ~@body))
+        m1 (if attr-map (if name-meta (conj name-meta attr-map) attr-map) name-meta)
-      `(def ~fn-name (fn ~fn-only-name ~@body)))))
+        meta-map (if docstring (assoc (if m1 m1 {}) :doc docstring) m1)]
+    ;; pass the name through to fn: the compiled fn's host name carries it, so
+    ;; stack traces read app.deep/level3 instead of a gensym. All metadata
+    ;; (docstring + attr-map + the name's own) is attached to the def name symbol,
+    ;; which analyze-def reads and evaluates — so (meta #'f) reflects every source.
+    (if meta-map
+      `(def ~(with-meta fn-only-name meta-map) (fn ~(with-meta fn-only-name nil) ~@body))
+      `(def ~fn-only-name (fn ~fn-only-name ~@body)))))
 
 ;; Jolt doesn't enforce privacy, so defn- is just defn (matching how Clojure's own
 ;; defn- delegates to defn with :private metadata).

test/chez/corpus.edn

@@ -3296,4 +3296,8 @@
   {:suite "ifn / symbol as fn" :label "a symbol invokes as a map lookup" :expected "true" :actual "(= 5 ('a {(quote a) 5}))"}
   {:suite "ifn / symbol as fn" :label "a symbol fn takes a not-found default" :expected "true" :actual "(= :d ('a {} :d))"}
   {:suite "ifn / symbol as fn" :label "a symbol works as a mapping fn" :expected "true" :actual "(= [1 2] (vec (map (quote k) [{(quote k) 1} {(quote k) 2}])))"}
+  {:suite "defn / attr-map" :label "docstring + attr-map both land in var meta" :expected "true" :actual "(do (defn f \"doc\" {:my :attr} [] 1) (= [\"doc\" :attr] [(:doc (meta (var f))) (:my (meta (var f)))]))"}
+  {:suite "defn / attr-map" :label "attr-map without a docstring" :expected "true" :actual "(do (defn g {:my :attr} [] 1) (= :attr (:my (meta (var g)))))"}
+  {:suite "defn / attr-map" :label "attr-map on a multi-arity defn" :expected "true" :actual "(do (defn h \"d\" {:my :a} ([] 1) ([a] a)) (= :a (:my (meta (var h)))))"}
+  {:suite "defn / attr-map" :label "attr-map values are evaluated" :expected "true" :actual "(do (defn m {:val (+ 1 2)} [] 1) (= 3 (:val (meta (var m)))))"}
 ]