erlang: Phase 9c — OP_PERFORM / OP_HANDLE stubs (+9 vm tests)

lib/erlang/scoreboard.json

@@ -1,7 +1,7 @@
 {
   "language": "erlang",
-  "total_pass": 656,
-  "total": 656,
+  "total_pass": 665,
+  "total": 665,
   "suites": [
     {"name":"tokenize","pass":62,"total":62,"status":"ok"},
     {"name":"parse","pass":52,"total":52,"status":"ok"},
@@ -13,6 +13,6 @@
     {"name":"echo","pass":7,"total":7,"status":"ok"},
     {"name":"fib","pass":8,"total":8,"status":"ok"},
     {"name":"ffi","pass":14,"total":14,"status":"ok"},
-    {"name":"vm","pass":19,"total":19,"status":"ok"}
+    {"name":"vm","pass":28,"total":28,"status":"ok"}
   ]
 }

lib/erlang/scoreboard.md

@@ -1,6 +1,6 @@
 # Erlang-on-SX Scoreboard
 
-**Total: 656 / 656 tests passing**
+**Total: 665 / 665 tests passing**
 
 |  | Suite | Pass | Total |
 |---|---|---|---|
@@ -14,7 +14,7 @@
 | ✅ | echo | 7 | 7 |
 | ✅ | fib | 8 | 8 |
 | ✅ | ffi | 14 | 14 |
-| ✅ | vm | 19 | 19 |
+| ✅ | vm | 28 | 28 |
 
 
 Generated by `lib/erlang/conformance.sh`.

lib/erlang/tests/vm.sx

@@ -134,4 +134,60 @@
   (string-contains? (str (nth er-vm-err-caught 0)) "unknown opcode")
   true)
 
+
+;; ── Phase 9c — OP_PERFORM / OP_HANDLE ───────────────────────────
+(er-vm-test "perform opcode by id"
+  (get (er-vm-lookup-opcode-by-id 131) :name) "OP_PERFORM")
+(er-vm-test "handle opcode by id"
+  (get (er-vm-lookup-opcode-by-id 132) :name) "OP_HANDLE")
+
+(define er-vm-pf-caught (list nil))
+(guard (c (:else (set-nth! er-vm-pf-caught 0 c)))
+  (er-vm-dispatch 131 (list "yield" (list 42))))
+(er-vm-test "perform raises tagged"
+  (get (nth er-vm-pf-caught 0) :tag) "vm-effect")
+(er-vm-test "perform effect name"
+  (get (nth er-vm-pf-caught 0) :effect) "yield")
+(er-vm-test "perform args carried"
+  (nth (get (nth er-vm-pf-caught 0) :args) 0) 42)
+
+(er-vm-test "handle catches matching effect"
+  (er-vm-dispatch 132
+    (list
+      (fn () (er-vm-dispatch 131 (list "yield" (list 7))))
+      "yield"
+      (fn (args) (+ (nth args 0) 100))))
+  107)
+
+(er-vm-test "handle no-effect returns thunk result"
+  (er-vm-dispatch 132
+    (list
+      (fn () 99)
+      "yield"
+      (fn (args) "handler ran")))
+  99)
+
+(define er-vm-rt-caught (list nil))
+(guard (c (:else (set-nth! er-vm-rt-caught 0 c)))
+  (er-vm-dispatch 132
+    (list
+      (fn () (er-vm-dispatch 131 (list "other" (list))))
+      "yield"
+      (fn (args) "wrong"))))
+(er-vm-test "handle rethrows non-matching"
+  (get (nth er-vm-rt-caught 0) :effect) "other")
+
+(er-vm-test "nested handles separate effect names"
+  (er-vm-dispatch 132
+    (list
+      (fn ()
+        (er-vm-dispatch 132
+          (list
+            (fn () (er-vm-dispatch 131 (list "b" (list 5))))
+            "a"
+            (fn (args) "inner-handled"))))
+      "b"
+      (fn (args) (+ (nth args 0) 1000))))
+  1005)
+
 (define er-vm-test-summary (str "vm " er-vm-test-pass "/" er-vm-test-count))

lib/erlang/vm/dispatcher.sx

@@ -80,6 +80,44 @@
         (error (str "Erlang VM: unknown opcode name '" name "'"))
         ((get entry :handler) operands)))))
 
+;; ── Phase 9c — effect opcodes (perform / handle) ────────────────
+;; Stub algebraic-effects-style operators. OP_PERFORM raises a tagged
+;; exception; OP_HANDLE wraps a thunk in `guard` and catches matching
+;; effects, passing the args to the handler. The real specialization
+;; (constant-time effect dispatch, single-shot vs multi-shot continuations)
+;; lands when 9a integrates.
+
+(define er-vm-effect-marker?
+  (fn (c effect-name)
+    (and (= (type-of c) "dict")
+         (= (get c :tag) "vm-effect")
+         (= (get c :effect) effect-name))))
+
+(define er-vm-op-perform
+  (fn (operands)
+    (raise {:tag "vm-effect" :effect (nth operands 0) :args (nth operands 1)})))
+
+(define er-vm-op-handle
+  (fn (operands)
+    (let ((thunk (nth operands 0))
+          (effect-name (nth operands 1))
+          (handler (nth operands 2))
+          (result (list nil))
+          (caught (list false))
+          (rethrow (list nil)))
+      (guard
+        (c
+          (:else
+            (cond
+              (er-vm-effect-marker? c effect-name)
+                (do (set-nth! caught 0 true)
+                    (set-nth! result 0 (handler (get c :args))))
+              :else (set-nth! rethrow 0 c))))
+        (set-nth! result 0 (thunk)))
+      (cond
+        (not (= (nth rethrow 0) nil)) (raise (nth rethrow 0))
+        :else (nth result 0)))))
+
 ;; ── Phase 9b — pattern-match opcodes ────────────────────────────
 ;; Each handler takes a list (pattern-ast value env) and returns
 ;; true/false, mutating env on success (same contract as the
@@ -118,6 +156,8 @@
           (nth operands 0)
           (nth operands 1)
           (nth operands 2))))
+    (er-vm-register-opcode! 131 "OP_PERFORM" er-vm-op-perform)
+    (er-vm-register-opcode! 132 "OP_HANDLE" er-vm-op-handle)
     (er-mk-atom "ok")))
 
 (er-vm-register-erlang-opcodes!)