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zaetrik/monocle-ts-compose-modifiers.ts

Last active June 4, 2020 18:19
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monocle-ts composing modifiers
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monocle-ts-compose-modifiers.ts
import { Lens } from "monocle-ts";
interface Street {
num: number;
name: string;
}
interface Address {
city: string;
street: Street;
}
interface Company {
name: string;
address: Address;
}
interface Employee {
name: string;
company: Company;
}
const employee: Employee = {
name: "john",
company: {
name: "awesome inc",
address: {
city: "london",
street: {
num: 23,
name: "high street"
}
}
}
};
const capitalize = (s: string): string =>
s.substring(0, 1).toUpperCase() + s.substring(1);
const company = Lens.fromProp<Employee>()("company");
const city = Lens.fromProp<Address>()("city");
const address = Lens.fromProp<Company>()("address");
const street = Lens.fromProp<Address>()("street");
const streetName = Lens.fromProp<Street>()("name");
const companyName = Lens.fromProp<Company>()("name");
const employeeName = Lens.fromProp<Employee>()("name");
const capitalizeStreetName = company
.compose(address)
.compose(street)
.compose(streetName)
.modify(capitalize);
const capitalizeCity = company
.compose(address)
.compose(city)
.modify(capitalize);
const capitalizeCompanyName = company.compose(companyName).modify(capitalize);
const capitalizeName = employeeName.modify(capitalize);
const compose = <F extends (x: any) => any>(...fns: Array<F>) => (
...[x]: Parameters<F>
): ReturnType<F> => fns.reduce((y, f) => f(y), x);
const composeModifiers = <T>(...modifiers: Array<(s: T) => T>) =>
compose<(s: T) => T>(...modifiers);
const capitalizeEmployee = composeModifiers<Employee>(
capitalizeName,
capitalizeCompanyName,
capitalizeStreetName,
capitalizeCity
);
console.log(capitalizeEmployee(employee));
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