Implement a more functional API

[StefanoMagrassi]

Description

Thanks to the shift to TS (see #11) we can fully use the fp-ts library in order to implement a more functional API both for base request and api layers.

Warning! The following is just a sketch - please refer to the official documentation once the v1.0.0 will be published

request()

import {TaskEither} from 'fp-ts/lib/TaskEither';

export type Mixed = {[key: string]: any} | object | number | string | boolean | null;

type Method = 'GET' | 'POST' | 'PUT' | 'PATCH' | 'DELETE' | 'OPTIONS';

interface HeadersMap {
  [k: string]: string;
}

class NetworkError {
  public readonly type: 'NetworkError' = 'NetworkError';
  constructor(readonly message: string, readonly uri: USVString) {}
}

class BadUrl {
  public readonly type: 'BadUrl' = 'BadUrl';
  constructor(readonly url: string, readonly response: AppyResponse<Mixed>) {}
}

class BadResponse {
  public readonly type: 'BadResponse' = 'BadResponse';
  constructor(readonly response: AppyResponse<Mixed>) {}
}

type AppyError = NetworkError | BadUrl | BadResponse;

interface AppyResponse<A> {
  headers: HeadersMap;
  status: number;
  statusText: string;
  url: string,
  body: A
}

declare function request(m: Method, u: USVString, o?: RequestInit): TaskEither<AppyError, AppyResponse<Mixed>>

USVString, RequestInit are defined in the standard lib.dom.d.ts

api()

import {TaskEither} from 'fp-ts/lib/TaskEither';
import {Decoder} from 'io-ts';
import {
  AppyError,
  AppyResponse,
  HeadersMap,
  Method,
  Mixed
} from './request';

interface ApiConfig {
  baseUri: string;
  id?: string;
  version?: string;
}

export class DecoderError {
  public readonly type: 'DecoderError' = 'DecoderError';
  constructor(errors: ValidationErrors[]);
}

type ApiError = AppyError | DecoderError;

interface ApOptions<A> extends RequestInit {
  headers?: HeadersMap;
  token: string;
  decoder: Decoder<Mixed, A>
}

type ApiTask<A> = TaskEither<ApiError, AppyResponse<A>>;

interface ApiRequest {
  <A>(m: Method, u: USVString, o:  ApiOptions<A>): ApiTask<A>;
}

interface ApiRequestNoMethod {
  <A>(u: USVString, o:  ApiOptions<A>): ApiTask<A>;
}

interface ApiMethods {
  request: ApiRequest,
  get: ApiRequestNoMethod,
  post: ApiRequestNoMethod,
  put: ApiRequestNoMethod,
  patch: ApiRequestNoMethod,
  del: ApiRequestNoMethod
}

declare function api(c: ApiConfig): ApiMethods

Steps

• request (implementation + tests)
• api (implementation + tests)
• documentation

[StefanoMagrassi]

resolved by #15