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import {Option, fromNullable} from 'fp-ts/lib/Option';
// keep it simple
export type Account = string;
export interface Bank {
balance: (account: Account) => Option<number>;
/// Deposit amount into account
///
/// This function increases the balance of the given account by the
/// specified amount. It's a `void` function hence implicitly
/// stateful: It's expected to change some internal state of the
/// implementing class.
///
/// @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;
}
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.');
}
}
export type Operation = GetBalance | Withdraw | Deposit;
export type GetBalance = {op: 'GetBalance'; account: Account};
export type Withdraw = {op: 'Withdraw'; account: Account; amount: number};
export type Deposit = {op: 'Deposit'; account: Account; amount: number};
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