cl: block + return-from — 13 new tests (140 eval, 312 total green)

Sentinel propagation in cl-eval-body; cl-eval-block catches matching
sentinels; BLOCK/RETURN-FROM/RETURN dispatch added to cl-eval-list.
Parser: CL strings now {:cl-type "string"} dicts for proper CL semantics.

lib/common-lisp/eval.sx

@@ -37,15 +37,19 @@
 
 ;; ── body evaluation ───────────────────────────────────────────────
 
+(define cl-block-return?
+  (fn (v) (and (dict? v) (= (get v "cl-type") "block-return"))))
+
 (define cl-eval-body
   (fn (forms env)
     (cond
       ((= (len forms) 0) nil)
       ((= (len forms) 1) (cl-eval (nth forms 0) env))
       (:else
-        (do
-          (cl-eval (nth forms 0) env)
-          (cl-eval-body (rest forms) env))))))
+        (let ((result (cl-eval (nth forms 0) env)))
+          (if (cl-block-return? result)
+            result
+            (cl-eval-body (rest forms) env)))))))
 
 ;; ── lambda-list binding helpers ───────────────────────────────────
 
@@ -266,6 +270,24 @@
       {:cl-type "function" :builtin-fn (get cl-builtins name)}))
   (keys cl-builtins))
 
+;; ── BLOCK / RETURN-FROM ───────────────────────────────────────────
+
+(define cl-eval-block
+  (fn (args env)
+    (let ((name (nth args 0))
+          (body (rest args)))
+      (let ((result (cl-eval-body body env)))
+        (if (and (cl-block-return? result)
+                 (= (get result "name") name))
+          (get result "value")
+          result)))))
+
+(define cl-eval-return-from
+  (fn (args env)
+    (let ((name (nth args 0))
+          (val  (if (> (len args) 1) (cl-eval (nth args 1) env) nil)))
+      {:cl-type "block-return" :name name :value val})))
+
 ;; ── special form evaluators ───────────────────────────────────────
 
 (define cl-eval-if
@@ -541,6 +563,11 @@
           ((= head "LOCALLY")      (cl-eval-body args env))
           ((= head "EVAL-WHEN")    (cl-eval-eval-when args env))
           ((= head "DEFUN")        (cl-eval-defun args env))
+          ((= head "BLOCK")        (cl-eval-block args env))
+          ((= head "RETURN-FROM")  (cl-eval-return-from args env))
+          ((= head "RETURN")
+            (let ((val (if (> (len args) 0) (cl-eval (nth args 0) env) nil)))
+              {:cl-type "block-return" :name nil :value val}))
           ((= head "DEFVAR")       (cl-eval-defvar args env false))
           ((= head "DEFPARAMETER") (cl-eval-defvar args env true))
           ((= head "DEFCONSTANT")  (cl-eval-defvar args env true))

lib/common-lisp/parser.sx

@@ -4,7 +4,7 @@
 ;;
 ;; AST representation:
 ;;   integer/float         → SX number (or {:cl-type "float"/:ratio ...})
-;;   string                → SX string
+;;   string "hello"        → {:cl-type "string" :value "hello"}
 ;;   symbol FOO            → SX string "FOO"  (upcase)
 ;;   symbol NIL            → nil
 ;;   symbol T              → true
@@ -96,7 +96,7 @@
             ((= type "integer") {:form (cl-convert-integer val) :rest nxt})
             ((= type "float") {:form {:cl-type "float" :value val} :rest nxt})
             ((= type "ratio") {:form {:cl-type "ratio" :value val} :rest nxt})
-            ((= type "string") {:form val :rest nxt})
+            ((= type "string") {:form {:cl-type "string" :value val} :rest nxt})
             ((= type "char") {:form {:cl-type "char" :value val} :rest nxt})
             ((= type "keyword") {:form {:cl-type "keyword" :name val} :rest nxt})
             ((= type "uninterned") {:form {:cl-type "uninterned" :name val} :rest nxt})

lib/common-lisp/tests/eval.sx

@@ -283,3 +283,45 @@
 (cl-test "mapcar: basic"
   (ev "(mapcar (lambda (x) (* x 2)) '(1 2 3))")
   (list 2 4 6))
+
+;; ── BLOCK / RETURN-FROM / RETURN ─────────────────────────────────
+
+(cl-test "block: last form value"
+  (ev "(block done 1 2 3)")
+  3)
+(cl-test "block: empty body"
+  (ev "(block done)")
+  nil)
+(cl-test "block: single form"
+  (ev "(block foo 42)")
+  42)
+(cl-test "block: return-from"
+  (ev "(block done 1 (return-from done 99) 2)")
+  99)
+(cl-test "block: return-from nil block"
+  (ev "(block nil 1 (return-from nil 42) 3)")
+  42)
+(cl-test "block: return-from no value"
+  (ev "(block done (return-from done))")
+  nil)
+(cl-test "block: nested inner return stays inner"
+  (ev "(block outer (block inner (return-from inner 1) 2) 3)")
+  3)
+(cl-test "block: nested outer return"
+  (ev "(block outer (block inner 1 2) (return-from outer 99) 3)")
+  99)
+(cl-test "return: shorthand for nil block"
+  (ev "(block nil (return 77))")
+  77)
+(cl-test "return: no value"
+  (ev "(block nil 1 (return) 2)")
+  nil)
+(cl-test "block: return-from inside let"
+  (ev "(block done (let ((x 5)) (when (> x 3) (return-from done x))) 0)")
+  5)
+(cl-test "block: return-from inside progn"
+  (ev "(block done (progn (return-from done 7) 99))")
+  7)
+(cl-test "block: return-from through function"
+  (ev "(block done (flet ((f () (return-from done 42))) (f)) nil)")
+  42)

plans/common-lisp-on-sx.md

@@ -57,7 +57,7 @@ Core mapping:
 
 ### Phase 2 — sequential eval + special forms
 - [x] `cl-eval-ast`: `quote`, `if`, `progn`, `let`, `let*`, `flet`, `labels`, `setq`, `setf` (subset), `function`, `lambda`, `the`, `locally`, `eval-when`
-- [ ] `block` + `return-from` via captured continuation
+- [x] `block` + `return-from` via captured continuation
 - [ ] `tagbody` + `go` via per-tag continuations
 - [ ] `unwind-protect` cleanup frame
 - [ ] `multiple-value-bind`, `multiple-value-call`, `multiple-value-prog1`, `values`, `nth-value`
@@ -124,6 +124,7 @@ data; format for string templating.
 
 _Newest first._
 
+- 2026-05-05: block + return-from — sentinel propagation in cl-eval-body; cl-eval-block catches matching sentinels; BLOCK/RETURN-FROM/RETURN dispatch in cl-eval-list; 13 new tests (140 eval, 312 total green). Parser: CL strings → {:cl-type "string"} dicts.
 - 2026-04-25: Phase 2 eval — 127 tests, 299 total green. `lib/common-lisp/eval.sx`: cl-eval-ast with quote/if/progn/let/let*/flet/labels/setq/setf/function/lambda/the/locally/eval-when; defun/defvar/defparameter/defconstant; built-in arithmetic (+/-/*//, min/max/abs/evenp/oddp), comparisons, predicates, list ops (car/cdr/cons/list/append/reverse/length/nth/first/second/third/rest), string ops, funcall/apply/mapcar. Key gotchas: SX reduce is (reduce fn init list) not (reduce fn list init); CL true literal is t not true; builtins registered in cl-global-env.fns via wrapper dicts for #' syntax.
 - 2026-04-25: Phase 1 lambda-list parser — 31 new tests, 172 total green. `cl-parse-lambda-list` in `parser.sx` + `tests/lambda.sx`. Handles &optional/&rest/&body/&key/&aux/&allow-other-keys, defaults, supplied-p. Key gotchas: `(when (> (len items) 0) ...)` not `(when items ...)` (empty list is truthy); custom `cl-deep=` needed for dict/list structural equality in tests.
 - 2026-04-25: Phase 1 reader/parser — 62 new tests, 141 total green. `lib/common-lisp/parser.sx`: cl-read/cl-read-all, lists, dotted pairs, quote/backquote/unquote/splice/#', vectors, #:uninterned, NIL→nil, T→true, reader macro wrappers.