letfn is a macro over a letfn* special form (Clojure semantics)

jolt modelled letfn as a special form directly, so (macroexpand-1 '(letfn …))
returned the form unchanged. Clojure's letfn is a macro that expands to letfn*,
and macroexpansion tooling (tools.macro, tools.analyzer) depends on that — its
special-form handlers key on letfn*, not letfn.

Split it the Clojure way:
- letfn* is now the special form (analyzer), taking flat name/fn-form pairs
  [name1 fn1 name2 fn2 …] — the letrec :let lowering is unchanged.
- letfn is a macro (00-syntax) turning each (name [params] body*) spec into a
  name + (fn name [params] body*) binding, so it expands to letfn*.

So (macroexpand-1 '(letfn [(f [x] x)] (f 1))) now yields
(letfn* [f (fn f [x] x)] (f 1)), and clojure.tools.macro passes its whole suite
(macrolet / symbol-macrolet / mexpand-all). Listed in docs + site.

make test green (+1 corpus row, 0 new divergences), shakesmoke byte-identical.
One re-mint (analyzer + the letfn macro); selfhost holds.
This commit is contained in:
Yogthos 2026-06-27 17:26:18 -04:00
parent 7891fa0d55
commit 21cd88deee
6 changed files with 341 additions and 330 deletions

View file

@ -159,6 +159,15 @@
(defmacro declare [& syms]
`(do ~@(map (fn* [s] `(def ~s)) syms)))
;; letfn is a macro over the letfn* special form, matching Clojure: each
;; (name [params] body*) spec becomes a name + a (fn name [params] body*) binding.
;; So (macroexpand-1 '(letfn …)) yields the letfn* form macroexpansion tooling
;; (tools.macro / tools.analyzer) expects, instead of an opaque special form.
(defmacro letfn [fnspecs & body]
(cons 'letfn*
(cons (reduce (fn [acc s] (conj (conj acc (first s)) (cons 'fn s))) [] fnspecs)
body)))
;; destructure — Clojure's binding-vector expander.
;; Turns a binding vector that may contain destructuring
;; patterns into a plain binding vector (alternating symbol / init-form) built from

View file

@ -40,7 +40,7 @@
;; analyzed in analyze-list), so keep them in sync by intent, not by equality.
(def ^:private handled
#{"quote" "if" "do" "def" "fn*" "let*" "loop*" "recur" "throw" "try"
"syntax-quote" "var" "letfn" "set!" "defmacro"})
"syntax-quote" "var" "letfn*" "set!" "defmacro"})
(defn- uncompilable [why]
(throw (str "jolt/uncompilable: " why)))
@ -286,26 +286,21 @@
n)]
n)))
;; letfn: (letfn [(name [params] body*)...] body*). The named local fns are
;; MUTUALLY recursive, so bind every name into the env BEFORE analyzing any spec
;; — each spec then resolves its siblings (and itself) as locals. Emitted as a
;; :let flagged :letrec so the back end knows the bindings forward-reference each
;; other: Chez lowers it to `letrec*`. The interpreter's shared mutable env already
;; gives the letrec semantics that a
;; compiled sequential let* lacks — the reason letfn was uncompilable before.
(defn- analyze-letfn [ctx items env]
(let [specs (vec (form-vec-items (nth items 1)))
names (mapv #(form-sym-name (first (vec (form-elements %)))) specs)
env* (add-locals env names)
binds (mapv (fn [spec]
(let [cl (vec (form-elements spec))]
;; Build (fn name [params] body*) and analyze through the fn
;; MACRO so destructuring params desugar (the fn* primitive
;; would not — same trick defmacro uses). The named fn means
;; self- and sibling-calls resolve and it carries its own name.
[(form-sym-name (first cl))
(analyze ctx (cons (symbol "fn") cl) env*)]))
specs)]
;; letfn*: (letfn* [name1 fn1 name2 fn2 …] body*) — the special form Clojure's
;; letfn macro expands to (flat name/fn-form pairs, the fn forms already named).
;; The named local fns are MUTUALLY recursive, so bind every name into the env
;; BEFORE analyzing any fn form — each then resolves its siblings (and itself) as
;; locals. Emitted as a :let flagged :letrec so the back end lowers it to
;; `letrec*`; the interpreter's shared mutable env gives the same semantics.
(defn- analyze-letfn* [ctx items env]
(let [bvec (vec (form-vec-items (nth items 1)))
n (quot (count bvec) 2)
names (mapv (fn [i] (form-sym-name (nth bvec (* 2 i)))) (range n))
env* (add-locals env names)
binds (mapv (fn [i]
[(nth names i)
(analyze ctx (nth bvec (inc (* 2 i))) env*)])
(range n))]
{:op :let :letrec true :bindings binds
:body (analyze-seq ctx (drop 2 items) env*)}))
@ -424,7 +419,7 @@
{:op :recur :recur-name rt
:args (mapv #(analyze ctx % env) (rest items))})
"try" (analyze-try ctx items env)
"letfn" (analyze-letfn ctx items env)
"letfn*" (analyze-letfn* ctx items env)
"fn*" (analyze-fn ctx items env)
;; Lower the backtick to construction code (zero runtime cost), then analyze
;; it — the macroexpand/compile-time step, per read -> macroexpand -> compile.