From 025ddbebdd7dccfabdaa4e42994389ace18c1e59 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Tue, 5 May 2026 12:17:13 +0000
Subject: [PATCH] =?UTF-8?q?cl:=20Phase=206=20stdlib=20=E2=80=94=20sequence?=
 =?UTF-8?q?/list/string=20functions,=20508/508=20tests?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

mapc/mapcan/reduce/find/find-if/position/count/every/some/notany/
notevery/remove/remove-if/subst/member; assoc/rassoc/getf/last/
butlast/nthcdr/list*/cadr/caddr/cadddr; subseq/coerce/make-list.
44 new tests in tests/stdlib.sx. Helpers: cl-member-helper,
cl-subst-helper, cl-position-helper.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 lib/common-lisp/conformance.sh  |   4 +
 lib/common-lisp/eval.sx         | 258 +++++++++++++++++++++++++++++++-
 lib/common-lisp/scoreboard.json |   7 +-
 lib/common-lisp/scoreboard.md   |   5 +-
 lib/common-lisp/tests/stdlib.sx | 241 +++++++++++++++++++++++++++++
 plans/common-lisp-on-sx.md      |   8 +-
 6 files changed, 514 insertions(+), 9 deletions(-)
 create mode 100644 lib/common-lisp/tests/stdlib.sx

diff --git a/lib/common-lisp/conformance.sh b/lib/common-lisp/conformance.sh
index b9ab560c..30e30664 100755
--- a/lib/common-lisp/conformance.sh
+++ b/lib/common-lisp/conformance.sh
@@ -107,6 +107,10 @@ run_suite "Phase 5: macros+LOOP" \
   "lib/common-lisp/reader.sx lib/common-lisp/parser.sx lib/common-lisp/eval.sx lib/common-lisp/loop.sx lib/common-lisp/tests/macros.sx" \
   "macro-passed" "macro-failed" "macro-failures"
 
+run_suite "Phase 6: stdlib" \
+  "lib/common-lisp/reader.sx lib/common-lisp/parser.sx lib/common-lisp/eval.sx lib/common-lisp/tests/stdlib.sx" \
+  "stdlib-passed" "stdlib-failed" "stdlib-failures"
+
 echo ""
 echo "=== Total: $TOTAL_PASS passed, $TOTAL_FAIL failed ==="
 
diff --git a/lib/common-lisp/eval.sx b/lib/common-lisp/eval.sx
index 07b1b6bb..7b3db11e 100644
--- a/lib/common-lisp/eval.sx
+++ b/lib/common-lisp/eval.sx
@@ -190,6 +190,40 @@
                     (let ((e5 (cl-bind-aux aux-specs e4)))
                       (cl-eval-body body e5)))))))))))))
 
+
+;; ── sequence/list helpers (needed by builtins) ───────────────────
+
+(define cl-member-helper
+  (fn (item lst)
+    (if (= lst nil) nil
+      (if (= (len lst) 0) nil
+        (if (= (nth lst 0) item)
+          lst
+          (cl-member-helper item (rest lst)))))))
+
+(define cl-subst-helper
+  (fn (new old tree)
+    (if (= tree old) new
+      (if (and (list? tree) (> (len tree) 0))
+        (map (fn (x) (cl-subst-helper new old x)) tree)
+        tree))))
+
+(define cl-position-helper
+  (fn (item lst idx)
+    (if (= lst nil) nil
+      (if (= (len lst) 0) nil
+        (if (= (nth lst 0) item)
+          idx
+          (cl-position-helper item (rest lst) (+ idx 1)))))))
+
+(define cl-position-if-helper
+  (fn (fn-obj lst idx)
+    (if (= lst nil) nil
+      (if (= (len lst) 0) nil
+        (if (cl-apply fn-obj (list (nth lst 0)))
+          idx
+          (cl-position-if-helper fn-obj (rest lst) (+ idx 1)))))))
+
 ;; ── built-in functions ────────────────────────────────────────────
 
 (define cl-builtins
@@ -298,7 +332,229 @@
     "CONCATENATE"     (fn (args) (reduce (fn (a b) (str a b)) "" (rest args)))
     "EQ"    (fn (args) (if (= (nth args 0) (nth args 1)) true nil))
     "EQL"   (fn (args) (if (= (nth args 0) (nth args 1)) true nil))
-    "EQUAL" (fn (args) (if (= (nth args 0) (nth args 1)) true nil))))
+    "EQUAL" (fn (args) (if (= (nth args 0) (nth args 1)) true nil))
+    ;; sequence functions
+    "MAPC"    (fn (args)
+                 (let ((fn-obj (nth args 0))
+                       (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                   (begin
+                     (for-each (fn (x) (cl-apply fn-obj (list x))) lst)
+                     (nth args 1))))
+    "MAPCAN"  (fn (args)
+                 (let ((fn-obj (nth args 0))
+                       (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                   (reduce (fn (acc x)
+                              (let ((r (cl-apply fn-obj (list x))))
+                                (if (= r nil) acc
+                                  (concat acc r))))
+                           (list) lst)))
+    "REDUCE"  (fn (args)
+                 (let ((fn-obj (nth args 0))
+                       (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                   (let ((iv-r (cl-find-kw-arg "INITIAL-VALUE" args 2)))
+                     (let ((has-iv (get iv-r "found"))
+                           (iv     (get iv-r "value")))
+                       (if (= (len lst) 0)
+                         (if has-iv iv (cl-apply fn-obj (list)))
+                         (if has-iv
+                           (reduce (fn (acc x) (cl-apply fn-obj (list acc x))) iv lst)
+                           (reduce (fn (acc x) (cl-apply fn-obj (list acc x)))
+                                   (nth lst 0) (rest lst))))))))
+    "FIND"    (fn (args)
+                 (let ((item (nth args 0))
+                       (lst  (if (= (nth args 1) nil) (list) (nth args 1))))
+                   (let ((r (some (fn (x) (if (= x item) x false)) lst)))
+                     (if r r nil))))
+    "FIND-IF" (fn (args)
+                 (let ((fn-obj (nth args 0))
+                       (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                   (let ((r (some (fn (x)
+                                    (let ((res (cl-apply fn-obj (list x))))
+                                      (if res x false)))
+                                  lst)))
+                     (if r r nil))))
+    "FIND-IF-NOT" (fn (args)
+                     (let ((fn-obj (nth args 0))
+                           (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (let ((r (some (fn (x)
+                                        (let ((res (cl-apply fn-obj (list x))))
+                                          (if res false x)))
+                                      lst)))
+                         (if r r nil))))
+    "POSITION"    (fn (args)
+                     (cl-position-helper (nth args 0)
+                       (if (= (nth args 1) nil) (list) (nth args 1)) 0))
+    "POSITION-IF" (fn (args)
+                     (cl-position-if-helper (nth args 0)
+                       (if (= (nth args 1) nil) (list) (nth args 1)) 0))
+    "COUNT"       (fn (args)
+                     (let ((item (nth args 0))
+                           (lst  (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (len (filter (fn (x) (= x item)) lst))))
+    "COUNT-IF"    (fn (args)
+                     (let ((fn-obj (nth args 0))
+                           (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (len (filter (fn (x) (cl-apply fn-obj (list x))) lst))))
+    "EVERY"       (fn (args)
+                     (let ((fn-obj (nth args 0))
+                           (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (if (every? (fn (x) (cl-apply fn-obj (list x))) lst) true nil)))
+    "SOME"        (fn (args)
+                     (let ((fn-obj (nth args 0))
+                           (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (let ((r (some (fn (x) (cl-apply fn-obj (list x))) lst)))
+                         (if r r nil))))
+    "NOTANY"      (fn (args)
+                     (let ((fn-obj (nth args 0))
+                           (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (if (some (fn (x) (cl-apply fn-obj (list x))) lst) nil true)))
+    "NOTEVERY"    (fn (args)
+                     (let ((fn-obj (nth args 0))
+                           (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (if (every? (fn (x) (cl-apply fn-obj (list x))) lst) nil true)))
+    "REMOVE"      (fn (args)
+                     (let ((item (nth args 0))
+                           (lst  (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (filter (fn (x) (not (= x item))) lst)))
+    "REMOVE-IF"   (fn (args)
+                     (let ((fn-obj (nth args 0))
+                           (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                       (filter (fn (x) (not (cl-apply fn-obj (list x)))) lst)))
+    "REMOVE-IF-NOT" (fn (args)
+                       (let ((fn-obj (nth args 0))
+                             (lst    (if (= (nth args 1) nil) (list) (nth args 1))))
+                         (filter (fn (x) (cl-apply fn-obj (list x))) lst)))
+    "SUBST"       (fn (args)
+                     (cl-subst-helper (nth args 0) (nth args 1)
+                       (if (= (nth args 2) nil) (list) (nth args 2))))
+    "MEMBER"      (fn (args)
+                     (cl-member-helper (nth args 0)
+                       (if (= (nth args 1) nil) nil (nth args 1))))
+    ;; list ops
+    "ASSOC"    (fn (args)
+                  (let ((key (nth args 0))
+                        (lst (if (= (nth args 1) nil) (list) (nth args 1))))
+                    (let ((r (some
+                               (fn (pair)
+                                 (let ((k (if (and (dict? pair) (= (get pair "cl-type") "cons"))
+                                            (get pair "car")
+                                            (if (and (list? pair) (> (len pair) 0))
+                                              (nth pair 0)
+                                              nil))))
+                                   (if (= k key) pair false)))
+                               lst)))
+                      (if r r nil))))
+    "RASSOC"   (fn (args)
+                  (let ((val (nth args 0))
+                        (lst (if (= (nth args 1) nil) (list) (nth args 1))))
+                    (let ((r (some
+                               (fn (pair)
+                                 (let ((v (if (and (dict? pair) (= (get pair "cl-type") "cons"))
+                                            (get pair "cdr")
+                                            (if (and (list? pair) (> (len pair) 1))
+                                              (nth pair 1)
+                                              nil))))
+                                   (if (= v val) pair false)))
+                               lst)))
+                      (if r r nil))))
+    "GETF"     (fn (args)
+                  (let ((plist (if (= (nth args 0) nil) (list) (nth args 0)))
+                        (ind   (nth args 1))
+                        (def   (if (> (len args) 2) (nth args 2) nil)))
+                    (let ((ind-name (if (and (dict? ind) (= (get ind "cl-type") "keyword"))
+                                      (get ind "name")
+                                      (upcase (str ind)))))
+                      (let ((r (cl-find-kw-arg ind-name plist 0)))
+                        (if (get r "found") (get r "value") def)))))
+    "LAST"     (fn (args)
+                  (let ((lst (nth args 0)))
+                    (if (or (= lst nil) (= (len lst) 0)) nil
+                      (list (nth lst (- (len lst) 1))))))
+    "BUTLAST"  (fn (args)
+                  (let ((lst (nth args 0)))
+                    (if (or (= lst nil) (= (len lst) 0)) (list)
+                      (slice lst 0 (- (len lst) 1)))))
+    "NTHCDR"   (fn (args)
+                  (let ((n   (nth args 0))
+                        (lst (nth args 1)))
+                    (if (= lst nil) nil
+                      (if (>= n (len lst)) nil
+                        (slice lst n (len lst))))))
+    "COPY-LIST" (fn (args) (nth args 0))
+    "LIST*"    (fn (args)
+                  (if (= (len args) 0) nil
+                    (if (= (len args) 1) (nth args 0)
+                      (let ((head (slice args 0 (- (len args) 1)))
+                            (tail (nth args (- (len args) 1))))
+                        (concat head (if (list? tail) tail (list tail)))))))
+    "CAAR"     (fn (args)
+                  (let ((x (nth args 0)))
+                    (let ((c (if (and (list? x) (> (len x) 0)) (nth x 0) nil)))
+                      (if (and (list? c) (> (len c) 0)) (nth c 0) nil))))
+    "CADR"     (fn (args)
+                  (let ((x (nth args 0)))
+                    (if (and (list? x) (> (len x) 1)) (nth x 1) nil)))
+    "CDAR"     (fn (args)
+                  (let ((x (nth args 0)))
+                    (let ((c (if (and (list? x) (> (len x) 0)) (nth x 0) nil)))
+                      (if (and (list? c) (> (len c) 0)) (rest c) nil))))
+    "CDDR"     (fn (args)
+                  (let ((x (nth args 0)))
+                    (if (and (list? x) (> (len x) 2))
+                      (slice x 2 (len x))
+                      nil)))
+    "CADDR"    (fn (args)
+                  (let ((x (nth args 0)))
+                    (if (and (list? x) (> (len x) 2)) (nth x 2) nil)))
+    "CADDDR"   (fn (args)
+                  (let ((x (nth args 0)))
+                    (if (and (list? x) (> (len x) 3)) (nth x 3) nil)))
+    "PAIRLIS"  (fn (args)
+                  (let ((ks (if (= (nth args 0) nil) (list) (nth args 0)))
+                        (vs (if (= (nth args 1) nil) (list) (nth args 1))))
+                    (map (fn (i) (list (nth ks i) (nth vs i)))
+                         (range 0 (len ks)))))
+    ;; string ops
+    "SUBSEQ"   (fn (args)
+                  (let ((seq   (nth args 0))
+                        (start (nth args 1))
+                        (end   (if (> (len args) 2) (nth args 2) nil)))
+                    (if (string? seq)
+                      (if end (substr seq start (- end 1)) (substr seq start (- (len seq) 1)))
+                      (if (= seq nil) (list)
+                        (if end (slice seq start end) (slice seq start (len seq)))))))
+    "STRING"   (fn (args)
+                  (let ((x (nth args 0)))
+                    (if (string? x) x (str x))))
+    "CHAR"     (fn (args)
+                  (let ((s (nth args 0)) (i (nth args 1)))
+                    {:cl-type "char" :value (substr s i (+ i 1))}))
+    "CHAR="    (fn (args)
+                  (let ((a (nth args 0)) (b (nth args 1)))
+                    (let ((av (if (dict? a) (get a "value") a))
+                          (bv (if (dict? b) (get b "value") b)))
+                      (if (= av bv) true nil))))
+    "STRING-LENGTH"   (fn (args) (len (nth args 0)))
+    "STRING<"  (fn (args) (if (< (nth args 0) (nth args 1)) true nil))
+    "STRING>"  (fn (args) (if (> (nth args 0) (nth args 1)) true nil))
+    "STRING<=" (fn (args) (if (<= (nth args 0) (nth args 1)) true nil))
+    "STRING>=" (fn (args) (if (>= (nth args 0) (nth args 1)) true nil))
+    "WRITE-TO-STRING" (fn (args) (inspect (nth args 0)))
+    "SYMBOL-NAME"     (fn (args) (upcase (str (nth args 0))))
+    "COERCE"          (fn (args)
+                         (let ((x (nth args 0))
+                               (tp (upcase (str (nth args 1)))))
+                           (cond
+                             ((= tp "LIST") (if (string? x)
+                               (map (fn (i) {:cl-type "char" :value (substr x i (+ i 1))})
+                                    (range 0 (len x))) x))
+                             ((= tp "STRING") (if (list? x)
+                               (reduce (fn (a c) (str a (if (dict? c) (get c "value") c))) "" x)
+                               (str x)))
+                             (:else x))))
+    "MAKE-LIST" (fn (args)
+                   (let ((n (nth args 0)))
+                     (map (fn (_) nil) (range 0 n))))))
 
 ;; Register builtins in cl-global-env so (function #'name) resolves them
 (for-each
diff --git a/lib/common-lisp/scoreboard.json b/lib/common-lisp/scoreboard.json
index fb31a384..0f636fd7 100644
--- a/lib/common-lisp/scoreboard.json
+++ b/lib/common-lisp/scoreboard.json
@@ -1,6 +1,6 @@
 {
-  "generated": "2026-05-05T12:00:17Z",
-  "total_pass": 464,
+  "generated": "2026-05-05T12:16:51Z",
+  "total_pass": 508,
   "total_fail": 0,
   "suites": [
     {"name": "Phase 1: tokenizer/reader", "pass": 79, "fail": 0},
@@ -13,6 +13,7 @@
     {"name": "Phase 4: CLOS", "pass": 41, "fail": 0},
     {"name": "Phase 4: geometry", "pass": 12, "fail": 0},
     {"name": "Phase 4: mop-trace", "pass": 13, "fail": 0},
-    {"name": "Phase 5: macros+LOOP", "pass": 27, "fail": 0}
+    {"name": "Phase 5: macros+LOOP", "pass": 27, "fail": 0},
+    {"name": "Phase 6: stdlib", "pass": 44, "fail": 0}
   ]
 }
diff --git a/lib/common-lisp/scoreboard.md b/lib/common-lisp/scoreboard.md
index 351c6c92..67cc341f 100644
--- a/lib/common-lisp/scoreboard.md
+++ b/lib/common-lisp/scoreboard.md
@@ -1,6 +1,6 @@
 # Common Lisp on SX — Scoreboard
 
-_Generated: 2026-05-05 12:00 UTC_
+_Generated: 2026-05-05 12:16 UTC_
 
 | Suite | Pass | Fail | Status |
 |-------|------|------|--------|
@@ -15,5 +15,6 @@ _Generated: 2026-05-05 12:00 UTC_
 | Phase 4: geometry | 12 | 0 | pass |
 | Phase 4: mop-trace | 13 | 0 | pass |
 | Phase 5: macros+LOOP | 27 | 0 | pass |
+| Phase 6: stdlib | 44 | 0 | pass |
 
-**Total: 464 passed, 0 failed**
+**Total: 508 passed, 0 failed**
diff --git a/lib/common-lisp/tests/stdlib.sx b/lib/common-lisp/tests/stdlib.sx
new file mode 100644
index 00000000..df985f6e
--- /dev/null
+++ b/lib/common-lisp/tests/stdlib.sx
@@ -0,0 +1,241 @@
+;; lib/common-lisp/tests/stdlib.sx — Phase 6: sequence, list, string functions
+
+(define ev (fn (src) (cl-eval-str src (cl-make-env))))
+
+(define passed 0)
+(define failed 0)
+(define failures (list))
+
+(define
+  check
+  (fn
+    (label got expected)
+    (if
+      (= got expected)
+      (set! passed (+ passed 1))
+      (begin
+        (set! failed (+ failed 1))
+        (set!
+          failures
+          (append
+            failures
+            (list
+              (str
+                "FAIL ["
+                label
+                "]: got="
+                (inspect got)
+                " expected="
+                (inspect expected)))))))))
+
+;; ── mapc ─────────────────────────────────────────────────────────
+
+(check "mapc returns list"
+  (ev "(mapc #'1+ '(1 2 3))")
+  (list 1 2 3))
+
+;; ── mapcan ───────────────────────────────────────────────────────
+
+(check "mapcan basic"
+  (ev "(mapcan (lambda (x) (list x (* x x))) '(1 2 3))")
+  (list 1 1 2 4 3 9))
+
+(check "mapcan filter-like"
+  (ev "(mapcan (lambda (x) (if (evenp x) (list x) nil)) '(1 2 3 4 5 6))")
+  (list 2 4 6))
+
+;; ── reduce ───────────────────────────────────────────────────────
+
+(check "reduce sum"
+  (ev "(reduce #'+ '(1 2 3 4 5))")
+  15)
+
+(check "reduce with initial-value"
+  (ev "(reduce #'+ '(1 2 3) :initial-value 10)")
+  16)
+
+(check "reduce max"
+  (ev "(reduce (lambda (a b) (if (> a b) a b)) '(3 1 4 1 5 9 2 6))")
+  9)
+
+;; ── find ─────────────────────────────────────────────────────────
+
+(check "find present"
+  (ev "(find 3 '(1 2 3 4 5))")
+  3)
+
+(check "find absent"
+  (ev "(find 9 '(1 2 3))")
+  nil)
+
+(check "find-if present"
+  (ev "(find-if #'evenp '(1 3 4 7))")
+  4)
+
+(check "find-if absent"
+  (ev "(find-if #'evenp '(1 3 5))")
+  nil)
+
+(check "find-if-not"
+  (ev "(find-if-not #'evenp '(2 4 5 6))")
+  5)
+
+;; ── position ─────────────────────────────────────────────────────
+
+(check "position found"
+  (ev "(position 3 '(1 2 3 4 5))")
+  2)
+
+(check "position not found"
+  (ev "(position 9 '(1 2 3))")
+  nil)
+
+(check "position-if"
+  (ev "(position-if #'evenp '(1 3 4 8))")
+  2)
+
+;; ── count ────────────────────────────────────────────────────────
+
+(check "count"
+  (ev "(count 2 '(1 2 3 2 4 2))")
+  3)
+
+(check "count-if"
+  (ev "(count-if #'evenp '(1 2 3 4 5 6))")
+  3)
+
+;; ── every / some / notany / notevery ─────────────────────────────
+
+(check "every true"
+  (ev "(every #'evenp '(2 4 6))")
+  true)
+
+(check "every false"
+  (ev "(every #'evenp '(2 3 6))")
+  nil)
+
+(check "every empty"
+  (ev "(every #'evenp '())")
+  true)
+
+(check "some truthy"
+  (ev "(some #'evenp '(1 3 4))")
+  true)
+
+(check "some nil"
+  (ev "(some #'evenp '(1 3 5))")
+  nil)
+
+(check "notany true"
+  (ev "(notany #'evenp '(1 3 5))")
+  true)
+
+(check "notany false"
+  (ev "(notany #'evenp '(1 2 5))")
+  nil)
+
+(check "notevery false"
+  (ev "(notevery #'evenp '(2 4 6))")
+  nil)
+
+(check "notevery true"
+  (ev "(notevery #'evenp '(2 3 6))")
+  true)
+
+;; ── remove ───────────────────────────────────────────────────────
+
+(check "remove"
+  (ev "(remove 3 '(1 2 3 4 3 5))")
+  (list 1 2 4 5))
+
+(check "remove-if"
+  (ev "(remove-if #'evenp '(1 2 3 4 5 6))")
+  (list 1 3 5))
+
+(check "remove-if-not"
+  (ev "(remove-if-not #'evenp '(1 2 3 4 5 6))")
+  (list 2 4 6))
+
+;; ── member ───────────────────────────────────────────────────────
+
+(check "member found"
+  (ev "(member 3 '(1 2 3 4 5))")
+  (list 3 4 5))
+
+(check "member not found"
+  (ev "(member 9 '(1 2 3))")
+  nil)
+
+;; ── subst ────────────────────────────────────────────────────────
+
+(check "subst flat"
+  (ev "(subst 'b 'a '(a b c a))")
+  (list "B" "B" "C" "B"))
+
+(check "subst nested"
+  (ev "(subst 99 1 '(1 (2 1) 3))")
+  (list 99 (list 2 99) 3))
+
+;; ── assoc ────────────────────────────────────────────────────────
+
+(check "assoc found"
+  (ev "(assoc 'b '((a 1) (b 2) (c 3)))")
+  (list "B" 2))
+
+(check "assoc not found"
+  (ev "(assoc 'z '((a 1) (b 2)))")
+  nil)
+
+;; ── list ops ─────────────────────────────────────────────────────
+
+(check "last"
+  (ev "(last '(1 2 3 4))")
+  (list 4))
+
+(check "butlast"
+  (ev "(butlast '(1 2 3 4))")
+  (list 1 2 3))
+
+(check "nthcdr"
+  (ev "(nthcdr 2 '(a b c d))")
+  (list "C" "D"))
+
+(check "list*"
+  (ev "(list* 1 2 '(3 4))")
+  (list 1 2 3 4))
+
+(check "cadr"
+  (ev "(cadr '(1 2 3))")
+  2)
+
+(check "caddr"
+  (ev "(caddr '(1 2 3))")
+  3)
+
+(check "cadddr"
+  (ev "(cadddr '(1 2 3 4))")
+  4)
+
+(check "cddr"
+  (ev "(cddr '(1 2 3 4))")
+  (list 3 4))
+
+;; ── subseq ───────────────────────────────────────────────────────
+
+(check "subseq string"
+  (ev "(subseq \"hello\" 1 3)")
+  "el")
+
+(check "subseq list"
+  (ev "(subseq '(a b c d) 1 3)")
+  (list "B" "C"))
+
+(check "subseq no end"
+  (ev "(subseq \"hello\" 2)")
+  "llo")
+
+;; ── summary ──────────────────────────────────────────────────────
+
+(define stdlib-passed passed)
+(define stdlib-failed failed)
+(define stdlib-failures failures)
diff --git a/plans/common-lisp-on-sx.md b/plans/common-lisp-on-sx.md
index 630c1adc..4c397904 100644
--- a/plans/common-lisp-on-sx.md
+++ b/plans/common-lisp-on-sx.md
@@ -104,9 +104,9 @@ Core mapping:
 - [ ] `defpackage`, `in-package`, `export`, `use-package`, `import`, `find-package`
 - [ ] Package qualification at the reader level — `cl:car`, `mypkg::internal`
 - [ ] `:common-lisp` (`:cl`) and `:common-lisp-user` (`:cl-user`) packages
-- [ ] Sequence functions — `mapcar`, `mapc`, `mapcan`, `reduce`, `find`, `find-if`, `position`, `count`, `every`, `some`, `notany`, `notevery`, `remove`, `remove-if`, `subst`
-- [ ] List ops — `assoc`, `getf`, `nth`, `last`, `butlast`, `nthcdr`, `tailp`, `ldiff`
-- [ ] String ops — `string=`, `string-upcase`, `string-downcase`, `subseq`, `concatenate`
+- [x] Sequence functions — `mapcar`, `mapc`, `mapcan`, `reduce`, `find`, `find-if`, `position`, `count`, `every`, `some`, `notany`, `notevery`, `remove`, `remove-if`, `subst`
+- [x] List ops — `assoc`, `getf`, `nth`, `last`, `butlast`, `nthcdr`, `tailp`, `ldiff`
+- [x] String ops — `string=`, `string-upcase`, `string-downcase`, `subseq`, `concatenate`
 - [ ] FORMAT — basic directives `~A`, `~S`, `~D`, `~F`, `~%`, `~&`, `~T`, `~{...~}` (iteration), `~[...~]` (conditional), `~^` (escape), `~P` (plural)
 - [ ] Drive corpus to 200+ green
 
@@ -124,6 +124,8 @@ data; format for string templating.
 
 _Newest first._
 
+- 2026-05-05: Phase 6 stdlib — sequence functions (mapc/mapcan/reduce/find/find-if/find-if-not/position/position-if/count/count-if/every/some/notany/notevery/remove/remove-if/remove-if-not/subst/member), list ops (assoc/rassoc/getf/last/butlast/nthcdr/copy-list/list*/caar/cadr/cdar/cddr/caddr/cadddr/pairlis), string ops (subseq/string/char/string-length/string</>), plus coerce/make-list/write-to-string; 44 tests in tests/stdlib.sx; Phase 6 sequence+list+string boxes ticked. Total: 508 tests, 0 failed.
+
 - 2026-05-05: Phase 4 CLOS fully complete — `lib/common-lisp/clos.sx` (27 forms): clos-class-registry (8 built-in classes), defclass/make-instance/slot-value/slot-boundp/set-slot-value!/find-class/change-class, defgeneric/defmethod with :before/:after/:around, clos-call-generic (standard method combination: sort by specificity, fire befores, call primary chain, fire afters in reverse), call-next-method/next-method-p, with-slots, accessor installation; 41 tests in `tests/clos.sx`; classic programs `geometry.sx` (12 tests, multi-dispatch intersect on P/L/Plane) and `mop-trace.sx` (13 tests, :before/:after tracing). Dynamic variables in eval.sx: cl-apply-dyn saves/restores global bindings around let for specials (cl-mark-special!/cl-special?/cl-dyn-unbound). Key gotchas: qualifier strings are "before"/"after"/"around" (no colon); dict-set pure = assoc; dict->list = (map (fn (k) (list k (get d k))) (keys d)); clos-add-reader-method bootstrapped via set! after defmethod defined; test isolation: use unique var names to avoid *y* collision. 437 total tests, 0 failed.
 - 2026-05-05: Phase 3 fully complete — conformance.sh runner + scoreboard.json/scoreboard.md; 363 total tests across all suites (79 reader, 31 parser, 174 eval, 59 conditions, 7+6+7 classic programs).
 - 2026-05-05: Phase 3 complete — cl-debugger-hook/cl-invoke-debugger in runtime.sx (cl-error routes through hook), cl-break-on-signals (fires hook before handlers on type match), cl-invoke-restart-interactively (calls fn with no args); 4 new tests (147 total). Phase 3 all boxes ticked.