Added to_string() and to_number() functions as built-ins.

examples/arrays.fun

@@ -1,3 +1,5 @@
+#!/usr/bin/env fun
+
 // Arrays basics
 arr = [1, 2, 3]
 print(arr)                 // -> [1, 2, 3]

examples/arrays_advanced.fun

@@ -1,3 +1,5 @@
+#!/usr/bin/env fun
+
 // Advanced Arrays Demo
 
 // Start with a basic array

examples/arrays_iter.fun

@@ -1,3 +1,5 @@
+#!/usr/bin/env fun
+
 // for-in over an array literal
 for x in [1, 2, 3]
   print(x)                 // prints: 1, then 2, then 3

examples/builtins_conversions.fun

@@ -0,0 +1,37 @@
+#!/usr/bin/env fun
+
+// Conversions and length built-ins demo
+
+// len on array and string
+print(len([1, 2, 3]))          // -> 3
+print(len("hello"))            // -> 5
+
+// to_number with various string inputs
+print(to_number("42"))         // -> 42
+print(to_number("   -7  "))    // -> -7
+print(to_number("12a"))        // non-numeric suffix -> 0
+print(to_number(""))           // empty -> 0
+print(to_number("  "))         // spaces -> 0
+
+// to_string on numbers and arrays
+print(to_string(42))           // -> "42" (printed as 42)
+
+arr = [1, 2]
+s = to_string(arr)             // -> "[array n=2]"
+print(s)
+
+// combine to_string with concatenation
+print("val=" + to_string(99))  // -> "val=99"
+
+/* Expected output:
+3
+5
+42
+-7
+0
+0
+0
+42
+[array n=2]
+val=99
+*/

examples/nested_loops.fun

@@ -1,3 +1,5 @@
+#!/usr/bin/env fun
+
 // Nested loops: break and continue behavior
 
 // 1) Nested for range: inner continue on j==2, inner break on j==4, outer break on i==3

examples/strings_test.fun

@@ -1,4 +1,5 @@
 #!/usr/bin/env fun
+
 // Strings test: concatenation with variables and literals, functions returning strings
 
 print("=== strings test start ===")