doc.ts

enum DocStatus {
    OPEN = "OPEN",
    WON = "WON",
    DRAFT = "DRAFT",
    OVERDUE = "OVERDUE",
    CANCELED = "CANCELED",
};

interface Doc {
    readonly id: string,
    readonly [propName: string]: any;
};

interface DocFn {
    <T extends Doc>(x: T, y?: any, z?: any): T;
};

interface Invoice extends Doc {
    readonly invoiceNumber: string,
    readonly status: DocStatus,
    readonly date?: string,
    readonly clientId?: string,
};

const invoices: Invoice[] = [
    { id: "1", invoiceNumber: "", status: DocStatus.OPEN },
    { id: "2", invoiceNumber: "", status: DocStatus.DRAFT },
    { id: "3", invoiceNumber: "", status: DocStatus.DRAFT },
    { id: "4", invoiceNumber: "", status: DocStatus.WON },
];

const makeStatusChange:Function = (x: DocStatus, y: DocStatus) => <T extends Doc>(c: T) => {
    return {
        ...c,
        status: (c.status === x) ? y : c.status,
    };
};

const openToCanceled:<T extends Doc>(c: T) => T = makeStatusChange(DocStatus.OPEN, DocStatus.CANCELED);


const newInvoices:Invoice[] = invoices.map(openToCanceled);

console.log(newInvoices);