v6; more modular (#374)

* more modular

* 6.0.0

* fix #328; document module.builtin

* delete obsolete tests

* serialize variable reevaluation

* fix stale computation with no inputs

* runtime.dispose tests

* 6.0.0-rc.1

* italicize variable names

* remove blank lines

* shared undefined promise

* 6.0.0

Author: mbostock

Diff for: .eslintignore

@@ -0,0 +1,24 @@
+name: Publish
+
+on:
+  workflow_dispatch: {}
+  release:
+    types: [published]
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: yarn
+      - run: yarn --frozen-lockfile
+      - run: yarn test
+      - run: npm publish
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}

Diff for: .github/workflows/nodejs.yml

@@ -0,0 +1,19 @@
+name: Test
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: yarn
+      - run: yarn --frozen-lockfile
+      - run: yarn test

Diff for: .github/workflows/publish.yml

@@ -1,6 +1,4 @@
-*.sublime-workspace
 .DS_Store
-.esm-cache/
 dist/
 node_modules
 npm-debug.log

Diff for: .github/workflows/test.yml

@@ -2,24 +2,14 @@ The Observable runtime is open source and released under the [ISC License](https
 
 ## Development
 
-Install dependencies:
+We use Yarn 1.x (Classic). To install dependencies:
 
 ```
 yarn
 ```
 
-Run tests with Mocha:
+To run tests with Mocha:
 
 ```
 yarn test
 ```
-
-Build with Rollup:
-
-```
-yarn prepublishOnly
-```
-
-## For internal use
-
-See our checklist for [publishing a new release](https://observablehq.com/@observablehq/publishing-new-open-source-releases).

Diff for: .gitignore

@@ -1,4 +1,4 @@
-Copyright 2018-2023 Observable, Inc.
+Copyright 2018-2024 Observable, Inc.
 
 Permission to use, copy, modify, and/or distribute this software for any purpose
 with or without fee is hereby granted, provided that the above copyright notice

Diff for: CONTRIBUTING.md

@@ -1,6 +1,6 @@
 {
   "name": "@observablehq/runtime",
-  "version": "5.9.9",
+  "version": "6.0.0",
   "author": {
     "name": "Observable, Inc.",
     "url": "https://observablehq.com"
@@ -9,38 +9,25 @@
   "type": "module",
   "main": "src/index.js",
   "module": "src/index.js",
-  "jsdelivr": "dist/runtime.umd.js",
-  "unpkg": "dist/runtime.umd.js",
   "exports": {
-    "umd": "./dist/runtime.umd.js",
     "default": "./src/index.js"
   },
   "repository": {
     "type": "git",
     "url": "https://github.com/observablehq/runtime.git"
   },
   "files": [
-    "dist/**/*.js",
     "src/**/*.js"
   ],
   "scripts": {
-    "test": "mocha 'test/**/*-test.js' && eslint src test",
-    "prepublishOnly": "rm -rf dist && rollup -c",
-    "postpublish": "git push && git push --tags"
+    "test": "mocha 'test/**/*-test.js' && eslint src test"
   },
   "_moduleAliases": {
     "@observablehq/runtime": "./src/index.js"
   },
-  "dependencies": {
-    "@observablehq/inspector": "^5.0.0",
-    "@observablehq/stdlib": "^5.0.0"
-  },
   "devDependencies": {
-    "@rollup/plugin-node-resolve": "^15.0.1",
     "eslint": "^8.27.0",
     "mocha": "^10.1.0",
-    "module-alias": "^2.2.2",
-    "rollup": "^3.2.5",
-    "rollup-plugin-terser": "^7.0.2"
+    "module-alias": "^2.2.2"
   }
 }

Diff for: LICENSE

@@ -1,4 +1,2 @@
-export {Inspector} from "@observablehq/inspector";
-export {Library} from "@observablehq/stdlib";
 export {RuntimeError} from "./errors.js";
 export {Runtime} from "./runtime.js";

Diff for: README.md

@@ -1,4 +1,3 @@
-import {Library, FileAttachments} from "@observablehq/stdlib";
 import {RuntimeError} from "./errors.js";
 import {generatorish} from "./generatorish.js";
 import {Module, variable_variable, variable_invalidation, variable_visibility} from "./module.js";
@@ -9,7 +8,7 @@ const frame = typeof requestAnimationFrame === "function" ? requestAnimationFram
   : typeof setImmediate === "function" ? setImmediate
   : f => setTimeout(f, 0);
 
-export function Runtime(builtins = new Library, global = window_global) {
+export function Runtime(builtins, global = window_global) {
   const builtin = this.module();
   Object.defineProperties(this, {
     _dirty: {value: new Set},
@@ -34,8 +33,7 @@ Object.defineProperties(Runtime.prototype, {
   _computeSoon: {value: runtime_computeSoon, writable: true, configurable: true},
   _computeNow: {value: runtime_computeNow, writable: true, configurable: true},
   dispose: {value: runtime_dispose, writable: true, configurable: true},
-  module: {value: runtime_module, writable: true, configurable: true},
-  fileAttachments: {value: FileAttachments, writable: true, configurable: true}
+  module: {value: runtime_module, writable: true, configurable: true}
 });
 
 function runtime_dispose() {
@@ -223,16 +221,22 @@ function variable_compute(variable) {
 
   const value0 = variable._value;
   const version = ++variable._version;
+  const inputs = variable._inputs;
+  const definition = variable._definition;
 
   // Lazily-constructed invalidation variable; only constructed if referenced as an input.
   let invalidation = null;
 
-  // If the variable doesn’t have any inputs, we can optimize slightly.
-  const promise = variable._promise = (variable._inputs.length
-      ? Promise.all(variable._inputs.map(variable_value)).then(define)
-      : new Promise(resolve => resolve(variable._definition.call(value0))))
+  // Wait for the previous definition to compute before recomputing.
+  const promise = variable._promise = variable._promise
+    .then(init, init)
+    .then(define)
     .then(generate);
 
+  function init() {
+    return Promise.all(inputs.map(variable_value));
+  }
+
   // Compute the initial value of the variable.
   function define(inputs) {
     if (variable._version !== version) throw variable_stale;
@@ -256,7 +260,7 @@ function variable_compute(variable) {
       }
     }
 
-    return variable._definition.apply(value0, inputs);
+    return definition.apply(value0, inputs);
   }
 
   // If the value is a generator, then retrieve its first value, and dispose of

Diff for: package.json

@@ -9,6 +9,7 @@ export const TYPE_IMPLICIT = 2; // created on reference
 export const TYPE_DUPLICATE = 3; // created on duplicate definition
 
 export const no_observer = Symbol("no-observer");
+export const no_value = Promise.resolve();
 
 export function Variable(type, module, observer, options) {
   if (!observer) observer = no_observer;
@@ -23,7 +24,7 @@ export function Variable(type, module, observer, options) {
     _module: {value: module},
     _name: {value: null, writable: true},
     _outputs: {value: new Set, writable: true},
-    _promise: {value: Promise.resolve(undefined), writable: true},
+    _promise: {value: no_value, writable: true},
     _reachable: {value: observer !== no_observer, writable: true}, // Is this variable transitively visible?
     _rejector: {value: variable_rejector(this)},
     _shadow: {value: initShadow(module, options)},