Functional Programming Example

oop-and-fp_fp.ts

type Customer = {
	firstname: string
	middlename: string
	lastname: string
	age: number
}

const formatSalesClerkCustomerName = (customer: Customer): string => {
	const formattedName = `${customer.lastname}, ${customer.firstname}`;
	return (customer.middlename && customer.middlename[0]) ?
		`${formattedName} ${customer.middlename[0]}.` : formattedName;
};

const isCutomerLegalAge = (customer: Customer): boolean => {
	return customer.age > 18;
};

const customerStatus = (customer: Customer): string => {
	return 'Status: ' + isCutomerLegalAge(customer)? 'Allowed' : 'Not Allowed'; 
};

const formatCustomerName = (
	customer: Customer,
	nameFormatter: (customer: Customer) => string): string => {
	return 'Name: ' + nameFormatter(customer);
};

const reportingFormatter = (customer: Customer): string => {
	
	throw new Error('not implemented yet');
};


let bran: Customer = {
	firstname: 'bran',
	middlename: 'tully',
	lastname: 'stark',
	age: 8
}

// Usage
formatCustomerName(bran, formatSalesClerkCustomerName);
formatCustomerName(bran, reportingFormatter);