@screenplaydev/retype
v0.3.1
Published
Reified types for Typescript.
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retype
Reified types for Typescript.
About
Retype gives you a way declare types in a way that the typesystem can read and can also be checked at runtime. The need came from declaring API routes which we wanted to be able to parse for developer experience wins, while still being able to validate at runtime.
Install
yarn add @screenplaydev/retype
Usage
import * as t from "@screenplaydev/retype";
const isBlogPost = t.shape({
title: t.string,
content: t.string,
author: t.optional(
t.shape({
name: t.string,
age: t.number,
})
),
});
type TBlogPost = t.TypeOf<typeof isBlogPost>;
isBlogPost({
title: "Hello world",
content: "Lorem ipsum...",
}); // returns true
isBlogPost({
foo: "bar",
}); // returns false
API Reference
JSON-ifiable Basics
t.nulltype
t.number
t.string
t.array(t.string)
t.shape({memberName: t.string})
JavaScript-isms
t.undefinedtype
t.literal("FOO" as const)
t.tuple([t.string, t.number])
t.union(t.string, t.number)
t.intersection(t.shape({name: t.string}), t.shape({age: t.number}))
Type relations
t.unionMany([t.number, t.string])
t.intersectMany([t.shape({name: t.string}), t.shape({age: t.number})])
t.literals(["FOO", "BAR"] as const)
Convenience
t.optional(t.string)
t.nullable(t.string)
Extension
Adding other validators is very simple, just add a function which returns a type predicate:
export const string = (value: unknown): value is string => {
return typeof value === "string";
};
Inspiration
Heavily inspired by io-ts.
License
MIT Licensed (see LICENSE.txt)
Copyright 2021, Screenplay Studios Inc.