refactor: separate promise handler function

__tests__/Result.js

@@ -9,7 +9,7 @@ import { Result, Ok, Err } from '../src';
  */
 
 test('Result(0) throws an error', () =>
-  expect(() => Result(0)).toThrow('Expected function or promise, got number')
+  expect(() => Result(0)).toThrow('Expected function, got number')
 );
 
 test('Result(fn) returns an `Ok` instance by default', () => {
@@ -26,26 +26,26 @@ test('Result(errFn) returns an `Err` instance', () => {
   expect(res).toBeInstanceOf(Err);
 });
 
-test('Result(Promise.resolve()) returns an `Ok` instance in a Promise', () => {
-  const prom = Result(Promise.resolve('Ok'));
+test('Result.promise(Promise.resolve()) makes an `Ok` instance', () => {
+  const prom = Result.promise(Promise.resolve('Ok'));
 
   return prom.then(res => expect(res).toBeInstanceOf(Result));
 });
 
-test('Result(Promise.reject()) returns an `Err` instance in a Promise', () => {
-  const prom = Result(Promise.reject('Oh no!'));
+test('Result.promise(Promise.reject()) makes an `Err` instance', () => {
+  const prom = Result.promise(Promise.reject('Oh no!'));
 
   return prom.then(res => expect(res).toBeInstanceOf(Result));
 });
 
-test('Result(succPromise) wraps the value correctly', () => {
-  const prom = Result(Promise.resolve('Ok'));
+test('Result.promise(succPromise) wraps the value correctly', () => {
+  const prom = Result.promise(Promise.resolve('Ok'));
 
   return prom.then(res => expect(res.get()).toBe('Ok'));
 });
 
-test('Result(errPromise) wraps the value correctly', () => {
-  const prom = Result(Promise.reject('Oh no!'));
+test('Result.promise(errPromise) wraps the value correctly', () => {
+  const prom = Result.promise(Promise.reject('Oh no!'));
 
   return prom.then(res => expect(res.getErr()).toBe('Oh no!'));
 });

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@fpc/result",
   "description": "Result type for modern javascript",
-  "version": "0.0.5",
+  "version": "0.0.6",
   "author": "Emiliano Bovetti <emiliano.bovetti@gmail.com>",
   "license": "GPL-3.0",
   "keywords": [

src/result.js

@@ -1,4 +1,4 @@
-import { isFunction, isPromise, typeOf } from '@fpc/types';
+import { expectFunction } from '@fpc/types';
 
 /* global Symbol */
 /* eslint-disable func-style, no-use-before-define, no-sequences */
@@ -48,22 +48,20 @@ Ctor.prototype = {
   },
 };
 
-export const Result = (src, ...args) => {
-  if (isFunction(src)) {
-    try {
-      const ret = src(...args);
-
-      return ret instanceof Result ? ret : new Ok(ret);
-    } catch (e) {
-      return e instanceof Err ? e : new Err(e);
-    }
-  } else if (isPromise(src)) {
-    return src.then(Ok, Err);
-  } else {
-    throw new TypeError(`Expected function or promise, got ${typeOf(src)}`);
+export const Result = (fn, ...args) => {
+  expectFunction(fn);
+
+  try {
+    const ret = fn(...args);
+
+    return ret instanceof Result ? ret : new Ok(ret);
+  } catch (e) {
+    return e instanceof Err ? e : new Err(e);
   }
 };
 
+Result.promise = promise => promise.then(Ok, Err);
+
 Result.prototype = Ctor.prototype;
 
 export function Ok (val) {