From 97b6722a113417398a1c47d583bfe07a906f87a0 Mon Sep 17 00:00:00 2001
From: Chris Wanstrath <chris@ozmm.org>
Date: Sun, 26 Oct 2025 12:52:57 -0700
Subject: [PATCH] support roundtrip value conversions

---
 src/index.ts        |  2 +-
 src/value.ts        | 10 +++++++++-
 tests/value.test.ts | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index 1fab29d..ce72660 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -13,5 +13,5 @@ export { wrapNative, isWrapped, type ParamInfo, extractParamInfo, getOriginalFun
 export { OpCode } from "./opcode"
 export { Scope } from "./scope"
 export type { Value, TypeScriptFunction, NativeFunction } from "./value"
-export { isValue, toValue, toString, toNumber, fromValue, toNull } from "./value"
+export { isValue, toValue, toString, toNumber, fromValue, toNull, fnFromValue } from "./value"
 export { VM } from "./vm"
\ No newline at end of file
diff --git a/src/value.ts b/src/value.ts
index be429e3..175c4a4 100644
--- a/src/value.ts
+++ b/src/value.ts
@@ -4,6 +4,7 @@ import { VM } from "./vm"
 
 export type NativeFunction = (...args: Value[]) => Promise<Value> | Value
 export type TypeScriptFunction = (this: VM, ...args: any[]) => any
+const REEF_FUNCTION = Symbol('__reefFunction')
 
 export type Value =
   | { type: 'null', value: null }
@@ -61,6 +62,8 @@ export function toValue(v: any): Value /* throws */ {
     case 'string':
       return { type: 'string', value: v }
     case 'function':
+      if ((v as any)[REEF_FUNCTION])
+        return (v as any)[REEF_FUNCTION]
       throw new Error("can't toValue() a js function yet")
     case 'object':
       const dict: Dict = new Map()
@@ -190,7 +193,7 @@ export function fnFromValue(fn: Value, vm: VM): Function {
   if (fn.type !== 'function')
     throw new Error('Value is not a function')
 
-  return async function (...args: any[]) {
+  const wrapper = async function (...args: any[]) {
     let positional: any[] = args
     let named: Record<string, any> = {}
 
@@ -226,4 +229,9 @@ export function fnFromValue(fn: Value, vm: VM): Function {
 
     return fromValue(newVM.stack.pop() || toNull(), vm)
   }
+
+    // support roundtrips, eg fromValue(toValue(fn))
+    ; (wrapper as any)[REEF_FUNCTION] = fn
+
+  return wrapper
 }
\ No newline at end of file
diff --git a/tests/value.test.ts b/tests/value.test.ts
index 193e087..46c1838 100644
--- a/tests/value.test.ts
+++ b/tests/value.test.ts
@@ -80,3 +80,36 @@ test("isValue - edge cases with type and value properties", () => {
   expect(isValue({ type: 'number', val: 42 })).toBe(false)
   expect(isValue({ typ: 'number', value: 42 })).toBe(false)
 })
+
+test("toValue - converts wrapped Reef functions back to original Value", async () => {
+  const { VM, toBytecode, fnFromValue } = await import("#reef")
+
+  // Create a Reef function
+  const bytecode = toBytecode([
+    ["MAKE_FUNCTION", ["x"], ".body"],
+    ["STORE", "add1"],
+    ["JUMP", ".end"],
+    [".body:"],
+    ["LOAD", "x"],
+    ["PUSH", 1],
+    ["ADD"],
+    ["RETURN"],
+    [".end:"],
+    ["HALT"]
+  ])
+
+  const vm = new VM(bytecode)
+  await vm.run()
+
+  const reefFunction = vm.scope.get("add1")!
+  expect(reefFunction.type).toBe("function")
+
+  // Convert to JS function
+  const jsFunction = fnFromValue(reefFunction, vm)
+  expect(typeof jsFunction).toBe("function")
+
+  // Convert back to Value - should return the original Reef function
+  const backToValue = toValue(jsFunction)
+  expect(backToValue).toBe(reefFunction)  // Same reference
+  expect(backToValue.type).toBe("function")
+})