cleanup, patterns

js-fp3/domain/account.js

@@ -1,4 +1,5 @@
 import { ok, fail } from '../library/result.js';
+import { match, when, any } from '../library/patterns.js';
 
 export const openingBalanceMustBeNonNegative = { type: 'OpeningBalanceMustBeNonNegative' };
 
@@ -20,15 +21,17 @@ export const openAccount = (id, openingBalance) =>
     ? fail(openingBalanceMustBeNonNegative)
     : ok({ id, balance: openingBalance });
 
-export const withdraw = (account, amount) => {
-  if (amount.amount <= 0) {
-    return fail(amountMustBePositive);
-  }
-  if (account.balance.amount < amount.amount) {
-    return fail(insufficientBalance(account.balance, amount));
-  }
-  return ok({
-    ...account,
-    balance: { amount: account.balance.amount - amount.amount },
-  });
-};
+export const withdraw = (account, amount) =>
+  match(
+    when(({ amount: a }) => a.amount <= 0, () => fail(amountMustBePositive)),
+    when(
+      ({ account: acc, amount: amt }) => acc.balance.amount < amt.amount,
+      ({ account: acc, amount: amt }) => fail(insufficientBalance(acc.balance, amt))
+    ),
+    when(any, ({ account: acc, amount: amt }) =>
+      ok({
+        ...acc,
+        balance: { amount: acc.balance.amount - amt.amount },
+      })
+    )
+  )({ account, amount });