core: fix jolt-r81 at root — move lazy-seq/lazy-cat to the early syntax tier

Root cause: lazy-seq/lazy-cat were defined in 30-macros, which loads AFTER the
seq/coll tiers (10-seq, 20-coll) that use them. In compile mode a tier's forms
are compiled as the tier loads, so (lazy-seq …) in those tiers was compiled when
lazy-seq was not yet a registered macro — i.e. as a CALL to the macro-as-function,
which at runtime returns its own expansion `(make-lazy-seq (fn* [] …))` as data.
That leaked form then flowed into ops like `odd?` (partition-by) → type errors,
or silently produced wrong structure. Interpret/self-host masked it (expand at
call time); the eager fallbacks and the earlier letfn versions masked it by
falling back to the interpreter.

Fix: define lazy-seq/lazy-cat in 00-syntax (loaded first), exactly as when-let
already is for the same reason. They use only seed fns (make-lazy-seq/coll->cells/
concat) + map. With the macro registered early, the seq/coll tiers compile
(lazy-seq …) correctly.

With the root fixed, interleave/reductions/tree-seq drop their letfn workarounds
and use the canonical recursive Clojure forms (top-level / fn-self-name recursion
inside lazy-seq), verified leak-free in compile mode with strict probes.

Regression guards added: partition-by with odd? (the strict pred that exposed the
leak; the prior case used identity which masked it), reductions over an infinite
range, tree-seq summed through a strict filter — all ×3 modes.

Gate: conformance 249x3, lazy-infinite 40/40, fixpoint, self-host, specs+unit green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -330,3 +330,16 @@
   (let [form (bindings 0) tst (bindings 1)]
     `(let [temp# ~tst]
        (if temp# (let [~form temp#] ~@body) nil))))
+
+;; lazy-seq / lazy-cat live here (not 30-macros) because the seq/coll tiers use
+;; them and compile-as-they-load: the macro must be registered before those tiers
+;; or (lazy-seq …) compiles to a call of the macro-as-function and leaks its
+;; expansion at runtime (jolt-r81). They use only seed fns (make-lazy-seq/
+;; coll->cells/concat) + map, all available from the start.
+;; lazy-seq defers its body: make-lazy-seq holds a thunk that realizes the body
+;; to cells when forced. lazy-cat wraps each coll in a lazy-seq and concats.
+(defmacro lazy-seq [& body]
+  `(make-lazy-seq (fn* [] (coll->cells (do ~@body)))))
+
+(defmacro lazy-cat [& colls]
+  `(concat ~@(map (fn [c] `(lazy-seq ~c)) colls)))

jolt-core/clojure/core/20-coll.clj

@@ -151,9 +151,7 @@
 (defn comparator [pred]
   (fn [a b] (cond (pred a b) -1 (pred b a) 1 :else 0)))
 
-;; Lazy: the running accumulators, one at a time (matches Clojure). Recursion is
-;; letfn-bound (NOT top-level self-call) so the lazy-seq body compiles cleanly in
-;; the overlay — see jolt-r81.
+;; Lazy: the running accumulators, one at a time (matches Clojure).
 (defn reductions
   ([f coll]
    (lazy-seq
@@ -162,18 +160,15 @@
          (reductions f (first s) (rest s))
          (list (f))))))
   ([f init coll]
-   (letfn [(step [acc s]
-             (cons acc
+   (cons init
          (lazy-seq
-                     (let [s (seq s)]
-                       (when s
-                         (step (f acc (first s)) (rest s)))))))]
-     (step init coll))))
+           (when-let [s (seq coll)]
+             (reductions f (f init (first s)) (rest s)))))))
 
-;; Lazy pre-order DFS (matches Clojure). letfn-bound walk (not (fn walk …)) so it
-;; compiles cleanly in the overlay under :compile? — see jolt-r81.
+;; Lazy pre-order DFS (matches Clojure): node, then its children's walks spliced
+;; via the (now lazy) mapcat.
 (defn tree-seq [branch? children root]
-  (letfn [(walk [node]
+  (let [walk (fn walk [node]
                (lazy-seq
                  (cons node
                        (when (branch? node)
@@ -190,28 +185,22 @@
   (tree-seq (complement string?) (comp seq :content) root))
 
 ;; Lazy interleave: round-robin one element from each coll until any exhausts.
-;; letfn-bound recursion (not top-level self-call) so the lazy-seq body compiles
-;; cleanly in the overlay — see jolt-r81.
 (defn interleave
   ([] ())
   ([c1] (lazy-seq c1))
   ([c1 c2]
-   (letfn [(step [s1 s2]
    (lazy-seq
-               (let [s1 (seq s1) s2 (seq s2)]
+     (let [s1 (seq c1) s2 (seq c2)]
        (when (and s1 s2)
          (cons (first s1)
                (cons (first s2)
-                               (step (rest s1) (rest s2))))))))]
-     (step c1 c2)))
+                     (interleave (rest s1) (rest s2))))))))
   ([c1 c2 & cs]
-   (letfn [(step [ss]
    (lazy-seq
-               (let [ss (map seq ss)]
+     (let [ss (map seq (list* c1 c2 cs))]
        (when (every? identity ss)
          (concat (map first ss)
-                           (step (map rest ss)))))))]
-     (step (list* c1 c2 cs)))))
+                 (apply interleave (map rest ss))))))))
 
 ;; No ratio type on Jolt, so rationalize is identity.
 (defn rationalize [x] x)

jolt-core/clojure/core/30-macros.clj

@@ -219,11 +219,8 @@
        ~@(map (fn [g] (impl (first g) (rest g))) (group-by-head body)))))
 
 ;; --- laziness --------------------------------------------------------------
-;; lazy-seq defers its body: make-lazy-seq holds a thunk that, when forced,
-;; realizes the body to cells. lazy-cat wraps each coll in a lazy-seq and concats
-;; (concat is itself lazy, so no outer wrapping needed).
-(defmacro lazy-seq [& body]
-  `(make-lazy-seq (fn* [] (coll->cells (do ~@body)))))
-
-(defmacro lazy-cat [& colls]
-  `(concat ~@(map (fn [c] `(lazy-seq ~c)) colls)))
+;; lazy-seq / lazy-cat moved to the 00-syntax tier: the seq/coll tiers (10-seq,
+;; 20-coll) use lazy-seq, and in compile mode a tier's forms are compiled as it
+;; loads — so the macro must be registered BEFORE those tiers, else (lazy-seq …)
+;; compiles as a call to the macro-as-function and leaks its expansion at runtime
+;; (jolt-r81). They only need seed fns (make-lazy-seq/coll->cells/concat).

test/integration/conformance-test.janet

@@ -152,6 +152,11 @@
    ["reductions"      "(quote (1 3 6 10))" "(reductions + [1 2 3 4])"]
    ["reductions init" "(quote (0 1 3 6))" "(reductions + 0 [1 2 3])"]
    ["dedupe"          "(quote (1 2 3 1))" "(dedupe [1 1 2 3 3 1])"]
+   # partition-by with a strict pred (odd?) — guards jolt-r81: a lazy overlay fn
+   # whose lazy-seq leaked its expansion in compile mode passed a non-int to odd?.
+   ["partition-by odd?" "(quote ((1 1) (2) (3 3)))" "(partition-by odd? [1 1 2 3 3])"]
+   ["reductions inf"  "(quote (0 1 3 6))" "(take 4 (reductions + (range)))"]
+   ["tree-seq strict" "10"  "(reduce + 0 (filter (complement coll?) (tree-seq coll? seq [1 [2 [3 4]]])))"]
    ["keep-indexed"    "(quote (:b :d))" "(keep-indexed (fn [i x] (if (odd? i) x)) [:a :b :c :d])"]
    ["map-indexed"     "(quote ([0 :a] [1 :b]))" "(map-indexed (fn [i x] [i x]) [:a :b])"]
    ["trampoline"      ":done"         "(do (defn a [n] (if (zero? n) :done (fn [] (a (dec n))))) (trampoline a 5))"]