restructure: move el compiler content into lang/

lang/examples/json-array-traversal.el

@@ -0,0 +1,21 @@
+// json-array-traversal.el — acceptance test for json_get dot-path with array
+// indices.
+//
+// Before fix: json_get("...", "0.field") would substring-search for a literal
+// key named `"0.field"` and find nothing, returning "".
+//
+// After fix: dot-path segments that are all digits are treated as array
+// indices and the walker descends into the array.
+
+fn test_array_traversal() -> String {
+    let s: String = "[{\"name\":\"alice\"},{\"name\":\"bob\"}]"
+    let a: String = json_get(s, "0.name")
+    let b: String = json_get(s, "1.name")
+    return a + "," + b
+}
+
+fn main() -> Int {
+    let r: String = test_array_traversal()
+    print(r)
+    return 0
+}