refactor: make result even more elm-y

I started with uppercasing the `R`.
Then, I replace  `Err` with `Failure` so it doesn't get mixed up with native JS errors.
I did the same with `Ok` and `Success`, so that the constructors line up.
I tried uppercasing the constructors as well, to make it more elmish.*
However, Eslint triggers `new-cap`, so I skipped that one and kept the Task terminology.
Also, because objects are really inconvenient,
I moved it to a folder and used evil barrel exports.

* I tried to come up with a Fable pun, but I couldn't think of one.

Author: lishaduck

lib/core.js

@@ -0,0 +1,61 @@
+/**
+ * Port of `elm/core` primitives to TS.
+ * Enables functional-style programming without having to pull in `Effect.TS`.
+ */
+
+/**
+ * @import {Fail, Success, Result} from './types/result';
+ */
+
+const {intoError} = require('./utils');
+
+/**
+ * Create a successful result.
+ *
+ * @template Value
+ *
+ * @param {Value} value
+ * @returns {Success<Value>}
+ */
+function succeed(value) {
+  return {tag: 'ok', value};
+}
+
+/**
+ * Create a failed result.
+ *
+ * @template Failure
+ *
+ * @param {Failure} failure
+ * @returns {Fail<Failure>}
+ */
+function fail(failure) {
+  return {tag: 'fail', failure};
+}
+
+/**
+ * Returns the value of a result, or throws if in an errored state.
+ *
+ * @remarks
+ * Converts errors into {@linkcode Error}s before throwing.
+ * For more details, see {@linkcode intoError}.
+ *
+ * @template Value
+ *
+ * @param {Result<unknown, Value>} value
+ * @returns {Value}
+ * @throws {Error}
+ */
+function orThrow(value) {
+  if (value.tag === 'ok') {
+    return value.value;
+  }
+
+  throw intoError(value.failure);
+}
+
+module.exports = {
+  succeed,
+  fail,
+  orThrow
+};

lib/result.js

@@ -5,7 +5,7 @@
 
 const https = require('node:https');
 const workerThreads = require('node:worker_threads');
-const {result} = require('./core');
+const Result = require('./result');
 
 /** @type {WorkerThreads<WorkerData>} */
 const {parentPort, workerData} = workerThreads;
@@ -17,11 +17,11 @@ if (parentPort) {
     try {
       const response = await getBody(url);
       requestPort.postMessage(
-        /** @satisfies {PortResponse} */ (result.succeed(response))
+        /** @satisfies {PortResponse} */ (Result.succeed(response))
       );
     } catch (error) {
       requestPort.postMessage(
-        /** @satisfies {PortResponse} */ (result.fail(error))
+        /** @satisfies {PortResponse} */ (Result.fail(error))
       );
     }
 

lib/sync-get-worker.js

@@ -8,7 +8,7 @@ const {
   MessageChannel,
   receiveMessageOnPort
 } = require('node:worker_threads');
-const {result} = require('./core');
+const Result = require('./result');
 
 /**
  * Start a worker thread and return a `syncGetWorker`
@@ -43,7 +43,7 @@ function startWorker() {
       return '';
     }
 
-    return result.orThrow(response.message);
+    return Result.orThrow(response.message);
   }
 
   /**

lib/sync-get.js

@@ -0,0 +1,3 @@
+export type Result<Error, Value> = Success<Value> | Fail<Error>;
+export type Success<Value> = {tag: 'ok'; value: Value};
+export type Fail<Failure> = {tag: 'fail'; failure: Failure};

lib/types/core.ts

@@ -1,5 +1,5 @@
 import type {MessagePort} from 'node:worker_threads';
-import type {Result} from './core.ts';
+import type {Result} from './result.js';
 
 export type WorkerData = {
   sharedLock: SharedArrayBuffer;