1 files changed, 31 insertions, 0 deletions
diff --git a/pbt/ts/src/bank.ts b/pbt/ts/src/bank.ts
new file mode 100644
index 0000000..bee9dfc
--- /dev/null
+++ b/pbt/ts/src/bank.ts
@@ -0,0 +1,31 @@
+import {Option, fromNullable} from 'fp-ts/lib/Option';
+
+// keep it simple
+export type Account = string;
+
+export interface Bank {
+  balance: (account: Account) => Option<number>;
+  deposit: (account: Account, amt: number) => void;
+  withdraw: (account: Account, amt: number) => void;
+}
+
+export class SimpleBank implements Bank {
+  private accounts: Map<Account, number>;
+
+  constructor(accounts: Map<Account, number>) {
+    // clone the content of the map
+    this.accounts = new Map(accounts);
+  }
+
+  balance(account: Account): Option<number> {
+    return fromNullable(this.accounts.get(account));
+  }
+
+  deposit(account: Account, amt: number): void {
+    throw new Error('Method not implemented.');
+  }
+
+  withdraw(account: Account, amt: number): void {
+    throw new Error('Method not implemented.');
+  }
+}