1 files changed, 11 insertions, 9 deletions
diff --git a/pbt/ts/src/bank.ts b/pbt/ts/src/bank.ts
index 1f47739..f5981a4 100644
--- a/pbt/ts/src/bank.ts
+++ b/pbt/ts/src/bank.ts
@@ -4,7 +4,7 @@ import {Option, fromNullable, matchW} from 'fp-ts/lib/Option';
 export type Account = string;
 
 export interface Bank {
-  balance: (account: Account) => Option<number>;
+  balance: (account: Account) => Promise<Option<number>>;
 
   /// Deposit amount into account
   ///
@@ -15,8 +15,8 @@ export interface Bank {
   ///
   /// @param account The account to deposit into
   /// @param amt The amount to deposit
-  deposit: (account: Account, amt: number) => void;
-  withdraw: (account: Account, amt: number) => void;
+  deposit: (account: Account, amt: number) => Promise<void>;
+  withdraw: (account: Account, amt: number) => Promise<void>;
 }
 
 export class SimpleBank implements Bank {
@@ -27,12 +27,12 @@ export class SimpleBank implements Bank {
     this.accounts = new Map(accounts);
   }
 
-  balance(account: Account): Option<number> {
-    return fromNullable(this.accounts.get(account));
+  balance(account: Account): Promise<Option<number>> {
+    return Promise.resolve(fromNullable(this.accounts.get(account)));
   }
 
-  deposit(account: Account, amt: number): void {
-    const current = this.balance(account);
+  deposit(account: Account, amt: number): Promise<void> {
+    const current = fromNullable(this.accounts.get(account));
     matchW(
       () => {
         throw new Error(`Unknown account ${account}`);
@@ -41,10 +41,11 @@ export class SimpleBank implements Bank {
         this.accounts.set(account, bal + amt);
       },
     )(current);
+    return Promise.resolve();
   }
 
-  withdraw(account: Account, amt: number): void {
-    const current = this.balance(account);
+  withdraw(account: Account, amt: number): Promise<void> {
+    const current = fromNullable(this.accounts.get(account));
     matchW(
       () => {
         throw new Error(`Unknown account ${account}`);
@@ -53,6 +54,7 @@ export class SimpleBank implements Bank {
         this.accounts.set(account, bal - amt);
       },
     )(current);
+    return Promise.resolve();
   }
 }