Bun compatibility for IO and HTTP

In the interest of supporting Bun, this commit makes many breaking
changes across existing modules. It also introduces Bun-specific IO
and HTTP modules, and auto-resolution between environment-specific
modules via `package.json` `imports` directives.

Due to inevitable breaking changes, opportunity was taken to cleanup
some other modules as well.

---

Breaking: replaced `live_deno.mjs` with a reworked `http_live.mjs`.
This module now works in both Bun and Deno.

---

Breaking: replaced `http_srv.mjs` with a reworked `http_shared.mjs`.

Added `concatStreams`.

Moved `EXT_TO_MIME_TYPE` and `guessContentType` to this file.

All features of this module are also exported by `http_deno.mjs`
and the new `http_bun.mjs`.

---

`http_deno.mjs`:

Breaking:
- Dropped:
  - `isErrCancel`
  - `dirAbs`
  - `dirRel`
  - `DirBase`
  - `Fil`
  - `HttpFileInfo` (see `HttpFile`)
  - `HttpFileStream` (no longer needed in Deno)
- Renamed:
  - `DirBase` → `BaseHttpDir`
  - `DirAbs` → `HttpDir`
  - `DirRel` → `HttpDir`
  - `DirRelFil` → `HttpDir` (merged 3 into 1)
  - `Dirs` → `HttpDirs`
- All "resolve file" directory methods now require a properly parsed
  URL pathname string, expecting the caller to handle its parsing.
  However, they do perform URL component decoding.

Added: `HttpFile`, which serves the same role as the earlier
`HttpFileInfo`, with almost the same API.

---

Added `http_bun.mjs` whose API nearly mirrors `http_deno.mjs`.

The environment-appropriate module is auto-resolved when importing
the pseudo-module `http`.

---

`io_deno.mjs`:

Breaking:
- Dropped:
  - `create` (use `writeFile`)
  - `touch`
  - `readTextCreate`
  - `readJson`
  - `filterWatch`
  - `FileInfo`
  - `isReader`
  - `reqReader`
  - `isCloser`
  - `reqCloser`
  - `ReaderStreamSource` (no longer needed in Deno)
  - `FileStream` (no longer needed in Deno)
  - `EnvMap`
- Renamed:
  - `readText` → `readFileText`
  - `readTextOpt` → `readFileTextOpt`
  - `readTextSync` → `readFileTextSync`
  - `readTextSyncOpt` → `readFileTextOptSync`
- Moved:
  - `ConcatStreamSource`: to `http_shared.mjs` / `http_deno.mjs`.
- Modified:
  - `watchCwd` and `watchRel` now yield events one-by-one.

Added:
- `ENV`
- `exit`
- `skipErrNotFound`
- `readFileBytes`
- `readFileBytesSync`
- `writeFileSync`
- `remove`
- `removeSync`
- `exists`
- `existsSync`
- `stat`
- `statSync`
- `statOpt`
- `statOptSync`
- `fileReadStream`
- `fileWriteStream`
- `readDir`
- `readDirSync`
- `validPath`

---

Added `io_bun.mjs` whose API almost mirrors `io_deno.mjs`, with some
differences which are expensive to fix:
- No `fileWriteStream`.
- `readDir` and `readDirSync` list strings, not stringable objects
  with metadata.

The environment-appropriate module is auto-resolved when importing
the pseudo-module `io`.

---

`dom.mjs`:

Breaking: dropped:
- `DOM_EXISTS`
- `isDomHandler`
- `reqDomHandler`
- `optDomHandler`
- `addEvents`
- `removeEvents`
- `clipNode`
- `setText`
- `mutDoc`
- `DocHeadMut`
- `DocBodyMut`
- `DocFoc`

Added:
- `eventDispatch`
- `eventListen`
- `ListenRef`

---

`http.mjs`:

Breaking: dropped:
- `Ctx..link`
- `Ctx..unlink`
- `Ctx..handleEvent`
- `Ctx..sub`

Improved memory management in `Ctx`. When linking a `Ctx` against a
parent signal, the signal and the child context now hold each other
weakly, via `ListenRef`. User code is now free to drop either the
parent signal or the child context without calling `.abort`, and the
dropped object will now be eligible for GC while the other one is
still in use. When a child context is GC-d, its listener is removed
from the parent signal. In engines without support for `WeakRef` or
`FinalizationRegistry`, references work as before this change.

Added `notFound`.

---

`iter.mjs`:

Breaking:
- Dropped:
  - `setOf`
  - `setCopy`
  - `mapOf`
- Renamed:
  - `setFrom` → `toSet`

---

`path.mjs`:

Breaking: dropped:
- `isPath` (use `lang.mjs` → `isScalar`)
- `reqPath` (use `lang.mjs` → `reqScalar`)
- `optPath` (use `lang.mjs` → `optScalar`)

Added `hasExt` which should be slightly faster than `!!ext(path)`.

---

`prax.mjs`:

`Ren..replaceChi` now avoids touching child nodes which occur in the
exact same positions at the start of both lists: existing child nodes
and new list of putative child nodes; but only at the start. This
avoids side-effectful disconnect / reconnect when repeatedly passing
the same starting children for the same target element.

---

`lang.mjs`:

Added `errSkip`.

Author: mitranim

.eslint.config.mjs

@@ -0,0 +1,120 @@
+export default [
+  {
+    languageOptions: {
+      ecmaVersion: 2022,
+      sourceType: `module`,
+      globals: {
+        console: `readonly`,
+        performance: `readonly`,
+        crypto: `readonly`,
+        queueMicrotask: `readonly`,
+        setTimeout: `readonly`,
+        clearTimeout: `readonly`,
+        setInterval: `readonly`,
+        clearInterval: `readonly`,
+        fetch: `readonly`,
+        URL: `readonly`,
+        URLSearchParams: `readonly`,
+        Request: `readonly`,
+        Response: `readonly`,
+        Headers: `readonly`,
+        AbortController: `readonly`,
+        AbortSignal: `readonly`,
+        Blob: `readonly`,
+        File: `readonly`,
+        Intl: `readonly`,
+        TextDecoder: `readonly`,
+        TextEncoder: `readonly`,
+        ReadableStream: `readonly`,
+        Event: `readonly`,
+        EventTarget: `readonly`,
+        CustomEvent: `readonly`,
+        FormData: `readonly`,
+      },
+    },
+    rules: {
+      [`no-restricted-globals`]: [`error`,
+        // window (browser)
+        `alert`, `blur`, `confirm`, `event`, `find`, `focus`, `history`,
+        `length`, `location`, `name`, `open`, `parent`, `print`,
+        `prompt`, `scroll`, `self`, `status`, `stop`, `top`,
+        // global (node)
+        `root`,
+        /* other */
+        `test`,
+        /* These global functions are broken */
+        `isNaN`, `isFinite`,
+      ],
+
+      [`consistent-return`]: `error`,
+      [`constructor-super`]: `error`,
+      [`eqeqeq`]: [`error`, `always`, {null: `never`}],
+      [`for-direction`]: `error`,
+      [`no-async-promise-executor`]: `error`,
+      [`no-case-declarations`]: `error`,
+      [`no-class-assign`]: `error`,
+      [`no-compare-neg-zero`]: `error`,
+      [`no-cond-assign`]: `error`,
+      [`no-const-assign`]: `error`,
+      [`no-constant-condition`]: `error`,
+      [`no-control-regex`]: `error`,
+      [`no-debugger`]: `error`,
+      [`no-delete-var`]: `error`,
+      [`no-dupe-args`]: `error`,
+      [`no-dupe-class-members`]: `error`,
+      [`no-dupe-else-if`]: `error`,
+      [`no-dupe-keys`]: `error`,
+      [`no-duplicate-case`]: `error`,
+      [`no-empty`]: [`error`, {allowEmptyCatch: true}],
+      [`no-empty-character-class`]: `error`,
+      [`no-empty-pattern`]: `error`,
+      [`no-ex-assign`]: `error`,
+      [`no-extra-boolean-cast`]: `error`,
+      [`no-extra-semi`]: `error`,
+      [`no-fallthrough`]: `error`,
+      [`no-func-assign`]: `error`,
+      [`no-global-assign`]: `error`,
+      [`no-import-assign`]: `error`,
+      [`no-inner-declarations`]: `error`,
+      [`no-invalid-regexp`]: `error`,
+      [`no-invalid-this`]: [`error`, {capIsConstructor: false}],
+      [`no-irregular-whitespace`]: `error`,
+      [`no-misleading-character-class`]: `error`,
+      [`no-mixed-spaces-and-tabs`]: `error`,
+      [`no-new-symbol`]: `error`,
+      [`no-obj-calls`]: `error`,
+      [`no-octal`]: `error`,
+      [`no-prototype-builtins`]: `error`,
+      [`no-redeclare`]: `error`,
+      [`no-regex-spaces`]: `error`,
+      [`no-self-assign`]: `error`,
+      [`no-setter-return`]: `error`,
+      [`no-shadow-restricted-names`]: `error`,
+      [`no-sparse-arrays`]: `error`,
+      [`no-this-before-super`]: `error`,
+      [`no-undef`]: `error`,
+      [`no-unexpected-multiline`]: `error`,
+      [`no-unreachable`]: `error`,
+      [`no-unsafe-finally`]: `error`,
+      [`no-unsafe-negation`]: `error`,
+      [`no-unused-expressions`]: `error`,
+      [`no-unused-labels`]: `error`,
+      [`no-unused-vars`]: [`error`, {argsIgnorePattern: `^_`, varsIgnorePattern: `^_`}],
+      [`no-useless-catch`]: `error`,
+      [`no-useless-escape`]: `error`,
+      [`no-warning-comments`]: [`error`, {location: `anywhere`, terms: [`FIXME`]}],
+      [`no-with`]: `error`,
+      [`object-curly-spacing`]: [`error`, `never`],
+      [`require-yield`]: `error`,
+      [`semi`]: [`error`, `never`],
+      [`use-isnan`]: `error`,
+      [`valid-typeof`]: `error`,
+
+      // [`quotes`]: [`error`, `backtick`], // Doesn't work properly.
+    },
+  },
+  {
+    files: [`doc/*.mjs`],
+    languageOptions: {ecmaVersion: 2025},
+  },
+]

.eslintrc

@@ -141,8 +141,7 @@ export class Flag extends s.StrMap {
 /*
 Simple "env" map with support for parsing "env properties" strings. The parser
 supports comments with `#` but not `!`, doesn't support backslash escapes, and
-doesn't allow whitespace around `=`. Doesn't perform any IO; see `io_deno.mjs`
-→ `EnvMap` which is a subclass.
+doesn't allow whitespace around `=`. Doesn't perform any IO.
 */
 export class EnvMap extends c.Bmap {
   set(key, val) {return super.set(l.reqStr(key), l.render(val))}
@@ -215,17 +214,21 @@ export function arrClearHard() {
   return ARR_CLEAR_HARD ??= new TextEncoder().encode(TERM_ESC_CLEAR_HARD)
 }
 
-export async function timed(tag, fun) {
+export function timed(tag, fun) {
   const pre = tag ? s.san`[${tag}] ` : ``
   const start = performance.now()
+  const out = fun()
+  if (l.isPromise(out)) return timedAsync(out, pre, start)
+  const end = performance.now()
+  console.log(s.san`${pre}done in ${end - start} ms`)
+  return out
+}
 
-  try {
-    return await fun()
-  }
-  finally {
-    const end = performance.now()
-    console.log(s.san`${pre}done in ${end - start} ms`)
-  }
+async function timedAsync(out, pre, start) {
+  out = await out
+  const end = performance.now()
+  console.log(s.san`${pre}done in ${end - start} ms`)
+  return out
 }
 
 /* Internal */

cli.mjs

@@ -8,7 +8,7 @@ Parser for CLI args. Features:
   * On-demand parsing of booleans and numbers.
 
 ```js
-const cli = cl.Flag.os()
-const args = cli.args
-const watch = cli.boolOpt(`w`)
+const flags = cl.Flag.os()
+const args = flags.args
+const watch = flags.boolOpt(`-w`)
 ```