Expand Gotlin language and tooling

examples/enums.gt

@@ -0,0 +1,22 @@
+package main
+
+enum PaymentResult {
+    Accepted(String)
+    Rejected(String)
+    Pending
+}
+
+fun describe(result: PaymentResult): String {
+    var description = ""
+    match (result) {
+        PaymentResult::Accepted(id) -> { description = "accepted " + id }
+        PaymentResult::Rejected(reason) -> { description = "rejected " + reason }
+        PaymentResult::Pending -> { description = "pending" }
+    }
+    return description
+}
+
+fun main() {
+    val result = PaymentResult::Accepted("payment-1")
+    println(describe(result))
+}