effection - npm Package Compare versions

Comparing version 0.0.2 to 0.1.0

package.json

 {
   "name": "effection",
-  "version": "0.0.2",
-  "description": "A structured concurrency library that makes working with side-effects in JavaScript lovely.",
-  "keywords": [
-    "concurrency",
-    "structured-concurrency",
-    "async",
-    "side-effects"
-  ],
-  "homepage": "https://github.com/cowboyd/effection.js#readme",
-  "bugs": {
-    "url": "https://github.com/cowboyd/effection.js/issues"
-  },
+  "description": "Effortlessly composable structured concurrency primitive for JavaScript",
+  "version": "0.1.0",
   "license": "MIT",
-  "author": "Charles Lowell <[e-mail]>, Taras Mankovski <[e-mail]>",
   "files": [
-    "src",
-    "README.md",
-    "dist"
+    "dist-*/",
+    "bin/",
+    "index.d.ts"
   ],
-  "main": "dist/effection.cjs.js",
-  "module": "dist/effection.es.js",
-  "repository": "git+ssh://[e-mail]/cowboyd/effection.js.git",
-  "scripts": {
-    "lint": "eslint ./",
-    "test": "mocha --recursive -r tests/setup tests",
-    "coverage": "nyc --reporter=html --reporter=text npm run test",
-    "coveralls": "nyc report --reporter=text-lcov | coveralls"
-  },
+  "esnext": "dist-src/index.js",
+  "main": "dist-node/index.js",
+  "module": "dist-web/index.js",
+  "pika": true,
+  "sideEffects": false,
+  "repository": "http://github.com/cowboyd/effection.js",
+  "dependencies": {},
   "devDependencies": {
-    "@babel/core": "7.0.0",
-    "@babel/preset-env": "^7.0.0",
-    "@babel/register": "^7.0.0",
-    "babel-eslint": "^10.0.1",
-    "coveralls": "3.0.2",
-    "eslint": "^5.7.0",
-    "eslint-plugin-prefer-let": "^1.0.1",
-    "expect": "^23.4.0",
-    "mocha": "^5.2.0",
     "nyc": "13.1.0",
-    "rollup": "^0.63.4",
-    "rollup-plugin-babel": "4.0.0-beta.7",
-    "rollup-plugin-filesize": "4.0.1",
-    "rollup-plugin-node-resolve": "3.3.0"
+    "@babel/core": "7.4.4",
+    "@babel/preset-env": "7.4.4",
+    "@babel/register": "7.4.4",
+    "@pika/pack": "0.3.7",
+    "@pika/plugin-build-node": "0.3.16",
+    "@pika/plugin-build-web": "0.3.16",
+    "@pika/plugin-copy-assets": "^0.3.16",
+    "@pika/plugin-standard-pkg": "0.3.16",
+    "@types/mocha": "^5.2.6",
+    "babel-eslint": "10.0.1",
+    "eslint": "5.16.0",
+    "eslint-plugin-prefer-let": "1.0.1",
+    "expect": "24.7.1",
+    "jest-mock": "^24.8.0",
+    "mocha": "6.1.4",
+    "ts-expect": "^1.1.0",
+    "ts-node": "^8.1.0",
+    "typescript": "^3.4.5"
   },
-  "dependencies": {},
-  "nyc": {
-    "exclude": [
-      "**/tests"
-    ]
-  }
+  "private": false
 }

README.md

@@ -8,5 +8,176 @@ [![npm](https://img.shields.io/npm/v/effection.svg)](https://www.npmjs.com/package/effection)
 
+# effection
 
-# ❤ Effection ❤️
+Effortlessly composable structured concurrency primitive for
+JavaScript
 
-A structured concurrency library that makes working with side-effects lovely.
+See [examples](examples/)
+
+To run an example with NAME:
+
+``` text
+$ node -r ./tests/setup examples/NAME
+```
+
+## Structured Concurrency and Effects
+
+> Note: For an general introduction to the concept of structured
+> concurrency, and why it is so important, see [this excellent primer
+> on the subject][1] by Nathaniel Smith.
+
+There's an entire hive of bugs that occur when asynchronous processes
+outlive their welcome. The concept of structured concurrency eliminates
+these altogether by providing the following guarantees:
+
+1. A process is considered pending (unfinished) while it is either
+   running or when it has _any_ child process that is pending.
+2. If an error occurs in a process that is not caught, then that error
+   propagates to the parent process.
+3. If a process finishes in error or by halting, then all of its child
+   process are immediately halted.
+
+For example, if you have the following processes:
+
+``` text
++ - parent
+  |
+  + --- child A
+  |
+  + --- child B
+```
+
+We can make the following assertions based on these guarantees :
+
+a. If the code associated with `parent` finishes running, but _either_ `A`
+_or_ `B` are pending, then `parent` is still considered pending.
+
+b. If `parent` is halted, then _both_ `A` and `B` are halted.
+
+c. If an error is raised in `parent`, then _both_ `A` and `B` are
+halted.
+
+d. if an error is raised in `A`, then that error is also raised in
+`parent`, _and_ child `B` is halted.
+
+scenario `d` is of particular importance. It means that if a child
+throws an error and its parent doesn't catch it, then all of its
+siblings are immediately halted.
+
+## Execution
+
+The process primitive is the `Execution`. To create (and start) an
+`Execution`, use the `execute` function and pass it a generator. This
+simplest example waits for 1 second, then prints out "hello world" to
+the console.
+
+``` javascript
+import { execute, timeout } from 'effection';
+
+let process = execute(function*() {
+  yield timeout(1000);
+  return 'hello world';
+});
+
+process.isRunning //=> true
+// 1000ms passes
+// process.isRunning //=> false
+// process.result //=> 'hello world'
+```
+
+Child processes can be composed freely. So instead of yielding for
+1000 ms, we could instead, yield 10 times for 100ms.
+
+``` javascript
+execute(function*() {
+  yield function*() {
+    for (let i = 0; i < 10; i++) {
+      yield timeout(100);
+    }
+  }
+  return 'hello world';
+})
+```
+
+And in fact, processes can be easily and arbitrarly deeply nested:
+
+``` javascript
+let process = execute(function*() {
+  return yield function*() {
+    return yield function*() {
+      return yield function*() {
+        return 'hello world';
+      }
+    };
+  };
+});
+
+process.isCompleted //=> true
+process.result //=> "hello world"
+```
+
+In order to abstract a process so that it can take arguments, you can
+use the `call` function:
+
+``` javascript
+
+import { execute, timeout, call } from 'effection';
+
+function* waitForSeconds(durationSeconds) {
+  yield timeout(durationSeconds * 1000);
+}
+
+execute(function*() {
+  yield call(waitforseconds, 10);
+});
+```
+
+More likely though, you would want to define a higher-order function
+that took your argument and returned a generator:
+
+
+``` javascript
+function waitForSeconds(durationSeconds) {
+  return function*() {
+    yield timeout(durationSeconds * 1000);
+  }
+}
+```
+
+### Asynchronous Execution
+
+Sometimes you want to execute some processes in parallel and not
+necessarily block further execution on them. You still want the
+guarantees associated with structured concurrency however. For
+example, you might want to create a couple of different servers as
+part of your main process. To do this, you would use the `fork` method
+on the execution:
+
+``` javascript
+import { execute } from 'effection';
+
+execute(function*() {
+  this.fork(createFileServer);
+  this.fork(createHttpServer);
+});
+```
+
+Even though it exits almost immediately, the main process is not
+considered completed until _both_ servers shutdown. More importantly
+though, if we shutdown the main process, then both servers will be
+halted.
+
+## Development
+
+yarn install
+
+``` text
+$ yarn
+```
+
+run tests:
+
+``` text
+$ yarn test
+```
+
+[1]: https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/

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