From 17d846b99910a46fc1c7ab98aa41ca8afbc14097 Mon Sep 17 00:00:00 2001
From: Chris Wanstrath <chris@ozmm.org>
Date: Sat, 25 Oct 2025 09:48:17 -0700
Subject: [PATCH] more repl support

---
 src/vm.ts          | 11 +++++++++--
 tests/repl.test.ts | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/src/vm.ts b/src/vm.ts
index 604cb38..aa3c948 100644
--- a/src/vm.ts
+++ b/src/vm.ts
@@ -83,8 +83,16 @@ export class VM {
   // Helper for REPL mode: append new bytecode with proper constant index remapping
   appendBytecode(bytecode: Bytecode): void {
     const constantOffset = this.constants.length
+    const instructionOffset = this.instructions.length
 
-    this.constants.push(...bytecode.constants)
+    // Remap function body addresses in constants before adding them
+    for (const constant of bytecode.constants) {
+      if (constant.type === 'function_def') {
+        this.constants.push({ ...constant, body: constant.body + instructionOffset })
+      } else {
+        this.constants.push(constant)
+      }
+    }
 
     for (const instruction of bytecode.instructions) {
       if (instruction.operand !== undefined && typeof instruction.operand === 'number') {
@@ -103,7 +111,6 @@ export class VM {
     }
 
     if (bytecode.labels) {
-      const instructionOffset = this.instructions.length - bytecode.instructions.length
       for (const [addr, label] of bytecode.labels.entries()) {
         this.labels.set(addr + instructionOffset, label)
       }
diff --git a/tests/repl.test.ts b/tests/repl.test.ts
index 8c65b28..35bb314 100644
--- a/tests/repl.test.ts
+++ b/tests/repl.test.ts
@@ -110,3 +110,40 @@ test("REPL mode - continue() executes only new bytecode", async () => {
   expect(line2Count).toBe(1) // Ran once as expected
   expect(result).toEqual({ type: "number", value: 15 }) // 5 + 10
 })
+
+test("REPL mode - function calls work across chunks", async () => {
+  const vm = new VM(toBytecode([]))
+  await vm.run()
+
+  // Line 1: Define a function
+  const line1 = toBytecode([
+    ["MAKE_FUNCTION", ["x"], ".body"],
+    ["STORE", "add1"],
+    ["JUMP", ".end"],
+    [".body:"],
+    ["LOAD", "x"],
+    ["PUSH", 1],
+    ["ADD"],
+    ["RETURN"],
+    [".end:"]
+  ])
+
+  vm.appendBytecode(line1)
+  await vm.continue()
+
+  expect(vm.scope.get("add1")?.type).toBe("function")
+
+  // Line 2: Call the function
+  const line2 = toBytecode([
+    ["LOAD", "add1"],
+    ["PUSH", 10],
+    ["PUSH", 1],
+    ["PUSH", 0],
+    ["CALL"]
+  ])
+
+  vm.appendBytecode(line2)
+  const result = await vm.continue()
+
+  expect(result).toEqual({ type: "number", value: 11 })
+})