chore: transfer sequence example (#590)

examples/transfer_sequence.ts

@@ -0,0 +1,36 @@
+import { alice, bob, charlie, Rune, Sr25519 } from "capi"
+import { Balances, System } from "westend_dev/mod.ts"
+
+await Rune
+  .chain(balances)
+  .chain(() => transfer("bob", bob))
+  .chain(balances)
+  .chain(() => transfer("charlie", charlie))
+  .chain(balances)
+  .run()
+
+function balances() {
+  return Rune
+    .rec({
+      alice: balance(alice),
+      bob: balance(bob),
+      charlie: balance(charlie),
+    })
+    .log("Balances:")
+}
+
+function balance(user: Sr25519) {
+  return System.Account.entry([user.publicKey]).access("data", "free")
+}
+
+function transfer(name: string, user: Sr25519) {
+  return Balances
+    .transfer({
+      dest: user.address,
+      value: 1000123n,
+    })
+    .signed({ sender: alice })
+    .sent()
+    .logStatus(`Transfer to ${name}:`)
+    .finalized()
+}

rune/Rune.ts

@@ -62,6 +62,10 @@ export class Rune<out T, out U = never> {
     return new Rune((batch) => new ctor(batch, ...args))
   }
 
+  static chain<T, U>(fn: () => Rune<T, U>): ValueRune<T, U> {
+    return fn().into(ValueRune)
+  }
+
   async run(batch = new Batch()): Promise<T> {
     for await (const value of this.iter(batch)) {
       return value