From 65b4b54b3fa5acc9ad7e87606a87d610c44d8015 Mon Sep 17 00:00:00 2001
From: Yogthos <yogthos@gmail.com>
Date: Sun, 7 Jun 2026 18:13:08 -0400
Subject: [PATCH] core: move lazy-seq and lazy-cat to the overlay

lazy-seq wraps its body in (make-lazy-seq (fn* [] (coll->cells (do ...)))); lazy-cat
wraps each coll in lazy-seq and concats (concat is already lazy). Both user-facing,
in 30-macros. Also drop two now-stale comments. Laziness preserved (lazy-seqs-spec
20/20, including infinite/self-referential).

conformance 228x3, fixpoint, clojure-test-suite 3930, full suite green.
---
 jolt-core/clojure/core/30-macros.clj | 14 +++++++++++---
 src/jolt/core.janet                  | 19 +------------------
 2 files changed, 12 insertions(+), 21 deletions(-)

diff --git a/jolt-core/clojure/core/30-macros.clj b/jolt-core/clojure/core/30-macros.clj
index cad7072..8678a57 100644
--- a/jolt-core/clojure/core/30-macros.clj
+++ b/jolt-core/clojure/core/30-macros.clj
@@ -83,7 +83,6 @@
         steps (map (fn [f] `(if (nil? ~g) nil (->> ~g ~f))) forms)]
     `(let [~g ~expr ~@(thread-binds g steps)] ~(if (empty? steps) g (last steps)))))
 
-;; cond-> stays in Janet (the compiler uses it); cond->> (thread-last) is safe.
 (defmacro cond->> [expr & clauses]
   (let [g (fresh-sym)
         steps (map (fn [pair] `(if ~(first pair) (->> ~g ~(second pair)) ~g))
@@ -137,8 +136,7 @@
 
 ;; --- protocols, records, types ---------------------------------------------
 ;; These emit Jolt's protocol/type special forms (protocol-dispatch,
-;; register-method, make-reified, deftype). The :jolt/protocol value built by
-;; defprotocol is an opaque tagged struct — it self-evaluates (see eval-form).
+;; register-method, make-reified, deftype).
 
 ;; Group a flat seq that starts with a head symbol followed by its list specs
 ;; into [[head spec spec ...] ...] runs. Used by extend-protocol and defrecord.
@@ -217,3 +215,13 @@
        (def ~arrow (fn* ~fields (~dot ~@fields)))
        (def ~mapf (fn* [~m] (~arrow ~@(map (fn [f] `(get ~m ~(keyword (name f)))) fields))))
        ~@(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)))
diff --git a/src/jolt/core.janet b/src/jolt/core.janet
index 3cac781..40a9190 100644
--- a/src/jolt/core.janet
+++ b/src/jolt/core.janet
@@ -1466,21 +1466,6 @@
 (defn core-disj [s & ks]
   (if (set? s) (apply phs-disj s ks) (error "disj expects a set")))
 
-(defn core-lazy-seq [& body]
-  @[{:jolt/type :symbol :ns nil :name "make-lazy-seq"}
-    @[{:jolt/type :symbol :ns nil :name "fn*"} []
-      @[{:jolt/type :symbol :ns nil :name "coll->cells"}
-        @[{:jolt/type :symbol :ns nil :name "do"} ;body]]]])
-
-(defn core-lazy-cat [& colls]
-  "Macro: (lazy-cat & colls) — concatenate lazy sequences, wrapping each coll in lazy-seq.
-  concat is now lazy, so no outer make-lazy-seq wrapping is needed."
-  (def concat-form @[])
-  (array/push concat-form {:jolt/type :symbol :ns nil :name "concat"})
-  (each c colls
-    (array/push concat-form @[{:jolt/type :symbol :ns nil :name "lazy-seq"} c]))
-  concat-form)
-
 (defn core-set [coll]
   (apply core-hash-set (realize-for-iteration coll)))
 
@@ -3026,8 +3011,6 @@
     "list" core-list
     "set?" core-set?
     "disj" core-disj
-    "lazy-seq" core-lazy-seq
-    "lazy-cat" core-lazy-cat
     "coll->cells" coll->cells
     "make-lazy-seq" make-lazy-seq
     "str" core-str
@@ -3255,7 +3238,7 @@
 (defn core-macro-names
   "Set of core binding names that are macros."
   []
-  @{"when-let" true "lazy-seq" true "lazy-cat" true})
+  @{"when-let" true})
 
 (def init-core!
   (fn [& args]