From e86c68dffaffee6ba44d98ba06761245f6d5b670 Mon Sep 17 00:00:00 2001
From: Kai Stevenson <kai@kaistevenson.com>
Date: Tue, 4 Nov 2025 20:53:37 -0800
Subject: add branching

---
 src/lang/js-lang/builtin/builtin.ts | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'src/lang/js-lang/builtin/builtin.ts')

diff --git a/src/lang/js-lang/builtin/builtin.ts b/src/lang/js-lang/builtin/builtin.ts
index dde91b6..d54c439 100644
--- a/src/lang/js-lang/builtin/builtin.ts
+++ b/src/lang/js-lang/builtin/builtin.ts
@@ -31,9 +31,24 @@ export const V_BUILTIN_Mul: BUILTIN = (args) => {
   );
 };
 
+export const V_BUILTIN_IfElse: BUILTIN = (args) => {
+  if (args.length !== 3) {
+    throw new Error(`Invalid args for "if": ${JSON.stringify(args)}`);
+  }
+
+  const [cond, trueVal, falseVal] = args;
+
+  if (typeof cond !== "boolean") {
+    throw new Error(`Condition value ${JSON.stringify(cond)} is not a boolean`);
+  }
+
+  return cond ? trueVal : falseVal;
+};
+
 export const nameToBUILTIN: Record<string, BUILTIN> = {
   arr: V_BUILTIN_Arr,
   tostring: V_BUILTIN_ToString,
   add: V_BUILTIN_Add,
   mul: V_BUILTIN_Mul,
+  "?": V_BUILTIN_IfElse,
 };
-- 
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