Added nested functions to the Fun parser. (0.40.0)

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.10)
-project(fun VERSION 0.39.16 LANGUAGES C)
+project(fun VERSION 0.40.0 LANGUAGES C)
 
 set(CMAKE_C_STANDARD 99)
 set(CMAKE_C_STANDARD_REQUIRED ON)

examples/functions/nested_functions.fun

@@ -0,0 +1,69 @@
+#!/usr/bin/env fun
+
+/*
+ * This file is part of the Fun programming language.
+ * https://fun-lang.xyz/
+ *
+ * Demonstrates nested functions that are only visible inside the
+ * outer function where they are defined. This example avoids
+ * capturing outer variables (closures) and instead passes values
+ * explicitly, which works with the current implementation.
+ *
+ * Added: 2026-04-02
+ */
+
+print("=== Nested functions (local to outer function) ===")
+
+// Outer function defines two inner helpers that are only usable inside outer
+fun outer(a, b)
+  // Defined inside outer; not visible as a global symbol
+  fun times3(x)
+    return x * 3
+  end
+
+  // Another local helper; also only visible within outer
+  fun sum_plus1(x, y)
+    return x + y + 1
+  end
+
+  // Use the local helpers
+  t1 = times3(a)
+  t2 = times3(b)
+  return sum_plus1(t1, t2)
+end
+
+print("outer(2, 5) -> expected 2*3 + 5*3 + 1 = 22")
+print(outer(2, 5))
+
+print("")
+print("=== Deeper nesting without variable capture ===")
+
+// Demonstrates function-inside-function-inside-function.
+// Each level avoids referencing outer locals directly; values
+// are threaded through parameters instead.
+fun demo_deep(n)
+  fun one(x)
+    fun two(y)
+      fun three(z)
+        return z + 1
+      end
+      return three(y) + 1
+    end
+    return two(x) + 1
+  end
+  return one(n)
+end
+
+print("demo_deep(4) -> expected 7")
+print(demo_deep(4))
+
+/*
+Expected output:
+=== Nested functions (local to outer function) ===
+outer(2, 5) -> expected 2*3 + 5*3 + 1 = 22
+22
+
+=== Deeper nesting without variable capture ===
+demo_deep(4) -> expected 7
+7
+*/

examples/snippets/nested.fun

@@ -0,0 +1,22 @@
+#!/usr/bin/env fun
+
+/*
+ * This file is part of the Fun programming language.
+ * https://fun-lang.xyz/
+ *
+ * Demonstrates nested functions that are only visible inside the
+ * outer function where they are defined. This example avoids
+ * capturing outer variables (closures) and instead passes values
+ * explicitly, which works with the current implementation.
+ *
+ * Added: 2026-04-02
+ */
+
+fun outer(x)
+  fun inner(y)
+    return y * 2
+  end
+  return inner(x) + inner(3)
+end
+
+print(outer(5))

examples/snippets/parse_test2.fun

@@ -1,12 +0,0 @@
-#!/usr/bin/env fun
-
-#include <net/cgi.fun>
-
-cgi = CGI()
-pairs = cgi._parse_urlencoded("a=1&b=2&c=3")
-i = 0
-n = len(pairs)
-while (i < n)
-  p = pairs[i]
-  print(to_string(p[0]) + "=" + to_string(p[1]))
-  i = i + 1

examples/snippets/test_parse.fun

@@ -1,5 +1,17 @@
 #!/usr/bin/env fun
 
+/*
+ * This file is part of the Fun programming language.
+ * https://fun-lang.xyz/
+ *
+ * Demonstrates nested functions that are only visible inside the
+ * outer function where they are defined. This example avoids
+ * capturing outer variables (closures) and instead passes values
+ * explicitly, which works with the current implementation.
+ *
+ * Added: 2026-04-02
+ */
+
 #include <net/cgi.fun>
 
 cgi = CGI()

src/parser.c

@@ -6692,10 +6692,34 @@ static void parse_block(Bytecode *bc, const char *src, size_t len, size_t *pos,
       }
 #endif
 
-      /* bind function to global: LOAD_CONST <fn> ; STORE_GLOBAL fgi */
+      /* If we are inside another function (prev != NULL), bind this function as a local
+       * so that it is only visible within the current function scope. Otherwise, bind
+       * it as a global (top-level behavior unchanged). */
       int fci = bytecode_add_constant(bc, make_function(fn_bc));
       bytecode_add_instruction(bc, OP_LOAD_CONST, fci);
+      if (prev != NULL) {
+        /* Bind into the OUTER function's local env (prev), not the inner temp env. */
+        LocalEnv *save_env = g_locals;
+        g_locals = prev;
+        /* declare a local with the function name if not present */
+        int lidx = local_find(fname);
+        if (lidx < 0) {
+          lidx = local_add(fname);
+        }
+        if (lidx < 0) {
+          /* failed to allocate local slot */
+          g_locals = save_env; /* restore before returning */
+          g_locals = prev;
+          free(fname);
+          return;
+        }
+        bytecode_add_instruction(bc, OP_STORE_LOCAL, lidx);
+        /* restore current env (will be reset to prev below) */
+        g_locals = save_env;
+      } else {
+        /* top-level: global binding (backward compatible) */
         bytecode_add_instruction(bc, OP_STORE_GLOBAL, fgi);
+      }
 
       g_locals = prev;
       free(fname);