From 58087fb9ccb3ebb716256d8f8332c506ebc699ff Mon Sep 17 00:00:00 2001
From: Torben Ewert <torben@ewert-online.com>
Date: Sat, 11 Jul 2026 22:12:54 +0200
Subject: [PATCH] test: add failing example of mutual recursion

---
 test/vm/functions.pi             | 20 ++++++++++++++++++++
 test/vm/functions.t              | 13 +++++++++++++
 test/vm/functions_instructions.t | 13 +++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/test/vm/functions.pi b/test/vm/functions.pi
index 08ddacf..574ce6e 100644
--- a/test/vm/functions.pi
+++ b/test/vm/functions.pi
@@ -100,3 +100,23 @@ component RecursiveFunction {
 
   fact_and_fib(5, 9)
 }
+
+component MutuallyRecursiveFunction {
+  let is_even = fn (i) -> {
+    if (i == 0) {
+      true
+    } else {
+      is_odd(i - 1)
+    }
+  };
+
+  let is_odd = fn (i) -> {
+    if (i == 0) {
+      false
+    } else {
+      is_even(i - 1)
+    }
+  };
+
+  is_even(1)
+}
diff --git a/test/vm/functions.t b/test/vm/functions.t
index d02395d..f48ea0a 100644
--- a/test/vm/functions.t
+++ b/test/vm/functions.t
@@ -26,3 +26,16 @@
 
   $ NO_COLOR="1" print_vm . RecursiveFunction
   154
+
+# TODO:
+  $ NO_COLOR="1" print_instructions . MutuallyRecursiveFunction
+  
+  ERROR in file ./functions.pi:109:7-13
+  
+   108 │     } else {
+   109 │       is_odd(i - 1)
+       │       ^^^^^^       
+   110 │     }
+  
+  Unbound identifier `is_odd`
+  [1]
diff --git a/test/vm/functions_instructions.t b/test/vm/functions_instructions.t
index 0c185bf..ceedbf4 100644
--- a/test/vm/functions_instructions.t
+++ b/test/vm/functions_instructions.t
@@ -314,3 +314,16 @@
   0026 I_Constant 0x0000000A (00000010)
   0031 I_Call 2
   0036 I_Pop
+
+# TODO:
+  $ NO_COLOR="1" print_instructions . MutuallyRecursiveFunction
+  
+  ERROR in file ./functions.pi:109:7-13
+  
+   108 │     } else {
+   109 │       is_odd(i - 1)
+       │       ^^^^^^       
+   110 │     }
+  
+  Unbound identifier `is_odd`
+  [1]
-- 
2.51.2