JsonDecoder for Typescript

ts version 2.2.1

running the examples

cd src
npm install
tsc main.ts
node main.js

Example

import * as Json from "./JsonDecoder";

type SomeDataType = {
    id: string,
    name: {
        firstname: string,
        lastname: string
    },
    hobbies: Array<string>,
    numbersAndStrings: Array<number|string>,
    optionalBoolean?: boolean
};

const decodeSomeDataType = Json.object<SomeDataType>({
    id: Json.string,
    name: Json.object({
        firstname: Json.string,
        lastname: Json.string
    }),
    hobbies: Json.array(Json.string),
    numbersAndStrings: Json.array(Json.oneOf<number|string>([Json.number, Json.string])),
    optionalBoolean: Json.maybe(undefined, Json.boolean)
});

console.log(decodeSomeDataType.run({
    id: "xy-12342",
    name: {
        firstname: "John",
        lastname: "Doe"
    },
    hobbies: [
        "Tennis",
        "Sleeping"
    ],
    numbersAndStrings: [
        1, 
        2,
        "foo",
        3,
        "bar"
    ]
}));

Combinators

string : Decoder<string>

number : Decoder<number>

boolean : Decoder<boolean>

maybe: <a>(defaultValue: a, decoder: Decoder<a>): Decoder<a>

nullable: <a>(decoder: Decoder<a>): Decoder<null|a>

isnull: <a>(defaultValue:a): Decoder<a>

isundefined: <a>(defaultValue:a): Decoder<a>

isexactly: <a>(value:a): Decoder<a>

array: (decoder: Decoder<a>): Decoder<Array<a>>

keyValues: <a>(decoder: Decoder<a>): Decoder<{[name:string]: a}>

oneOf: (decoders: Array<Decoder<a>>): Decoder<a>

constant: <a>(value:a): Decoder<a>

lazy: <a>(mkDecoder: () => Decoder<a>): Decoder<a>

object: <a>(decoders: DecoderObject<a>): Decoder<a>

type DecoderObject<a> = {[t in keyof a]: Decoder<a[t]>}

decoder.map(f)

decoder.then(f)

decoder.run(json)

decoder.runThen(json, onOk, onErr)

decoder.runPromise(json) : Promise<a>