From 0e387fcfe143281b9e58dd080408075d21f45af6 Mon Sep 17 00:00:00 2001
From: Chris Wanstrath <chris@ozmm.org>
Date: Sun, 5 Oct 2025 20:22:03 -0700
Subject: [PATCH] no continue, just JUMP

---
 SPEC.md             | 11 +----------
 src/bytecode.ts     |  2 +-
 src/opcode.ts       |  1 -
 src/vm.ts           | 25 -------------------------
 tests/basic.test.ts | 30 ++++++++++++++++++------------
 5 files changed, 20 insertions(+), 49 deletions(-)

diff --git a/SPEC.md b/SPEC.md
index f0b86b7..c6946b4 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -250,16 +250,7 @@ end:
 3. Stop when finding frame with `isBreakTarget = true`
 4. Resume execution at that frame's return address
 
-#### CONTINUE
-**Operand**: None  
-**Effect**: Unwind to nearest frame with `continueAddress`, jump there  
-**Stack**: No change  
-**Errors**: Throws if no continue target found
-
-**Behavior**:
-1. Search call stack (without popping) for frame with `continueAddress`
-2. When found, restore scope and jump to `continueAddress`
-3. Pop all frames above the continue target
+**Note on CONTINUE**: There is no CONTINUE opcode. Compilers implement continue behavior using JUMP with negative offsets to jump back to the loop start.
 
 ### Exception Handling
 
diff --git a/src/bytecode.ts b/src/bytecode.ts
index f98b96b..dd6b487 100644
--- a/src/bytecode.ts
+++ b/src/bytecode.ts
@@ -121,7 +121,7 @@ export function toBytecode(str: string): Bytecode /* throws */ {
       // Special handling for MAKE_FUNCTION with paren syntax
       if (opCode === OpCode.MAKE_FUNCTION && operand.startsWith('(')) {
         // Parse: MAKE_FUNCTION (params) #body
-        const match = operand.match(/^(\(.*?\))\s+(#\d+)$/)
+        const match = operand.match(/^(\(.*?\))\s+(#-?\d+)$/)
         if (!match) {
           throw new Error(`Invalid MAKE_FUNCTION syntax: ${operand}`)
         }
diff --git a/src/opcode.ts b/src/opcode.ts
index a00f0c0..098183b 100644
--- a/src/opcode.ts
+++ b/src/opcode.ts
@@ -31,7 +31,6 @@ export enum OpCode {
   JUMP_IF_FALSE,
   JUMP_IF_TRUE,
   BREAK,
-  CONTINUE,
 
   // exception handling
   PUSH_TRY,
diff --git a/src/vm.ts b/src/vm.ts
index 0bd522c..7f31673 100644
--- a/src/vm.ts
+++ b/src/vm.ts
@@ -162,31 +162,6 @@ export class VM {
           throw new Error('BREAK: no break target found')
         break
 
-      case OpCode.CONTINUE:
-        // Search for frame with continueAddress (don't pop yet)
-        let continueFrame: Frame | undefined
-        let frameIndex = this.callStack.length - 1
-        while (frameIndex >= 0) {
-          const frame = this.callStack[frameIndex]!
-          if (frame.continueAddress !== undefined) {
-            continueFrame = frame
-            break
-          }
-          frameIndex--
-        }
-
-        if (!continueFrame)
-          throw new Error('CONTINUE: no continue target found')
-
-        // Pop all frames above the continue target
-        while (this.callStack.length > frameIndex + 1)
-          this.callStack.pop()
-
-        // Restore scope and jump to continue address
-        this.scope = continueFrame.returnScope
-        this.pc = continueFrame.continueAddress! - 1  // -1 because PC will be incremented
-        break
-
       case OpCode.PUSH_TRY:
         const catchAddress = instruction.operand as number
         this.exceptionHandlers.push({
diff --git a/tests/basic.test.ts b/tests/basic.test.ts
index 4d81f7f..4c164ec 100644
--- a/tests/basic.test.ts
+++ b/tests/basic.test.ts
@@ -554,20 +554,26 @@ test("BREAK - exits from nested function call", async () => {
   expect(result).toEqual({ type: 'number', value: 42 })
 })
 
-test("CONTINUE - throws error when no continue target", async () => {
-  // CONTINUE requires continueAddress to be set on a frame
-  // Since we have no instruction to set it yet, this should throw
+test("JUMP backward - simple loop", async () => {
+  // Very simple: counter starts at 0, loops 3 times incrementing
+  // On 3rd iteration (counter==3), exits and returns counter
   const bytecode = toBytecode(`
-    MAKE_FUNCTION () #3
-    CALL #0
+    PUSH 0
+    STORE counter
+    LOAD counter
+    PUSH 3
+    EQ
+    JUMP_IF_FALSE #2
+    LOAD counter
     HALT
-    CONTINUE
+    LOAD counter
+    PUSH 1
+    ADD
+    STORE counter
+    JUMP #-11
   `)
 
-  try {
-    await run(bytecode)
-    expect(true).toBe(false)  // Should not reach here
-  } catch (e: any) {
-    expect(e.message).toContain('no continue target found')
-  }
+  const result = await run(bytecode)
+  expect(result).toEqual({ type: 'number', value: 3 })
 })
+