diff --git a/jsr.json b/jsr.json
index 94e5ffa..a26d61e 100644
--- a/jsr.json
+++ b/jsr.json
@@ -2,16 +2,13 @@
   "name": "@ihate-work/ts-commonutil",
   "version": "0.1.0",
   "exports": {
-    "./algebra/monoid": "./src/algebra/monoid.ts",
     "./algebra/topological-sort": "./src/algebra/topological-sort.ts",
-    "./algebra/total-ordered": "./src/algebra/total-ordered.ts",
-    "./binary-conversion/array-buffer": "./src/binary-conversion/array-buffer.ts",
-    "./binary-conversion/string": "./src/binary-conversion/string.ts",
-    "./binary-conversion/web": "./src/binary-conversion/web.ts",
+    "./bytes/array-buffer": "./src/bytes/array-buffer.ts",
+    "./bytes/string": "./src/bytes/string.ts",
+    "./bytes/web": "./src/bytes/web.ts",
     "./collection/btree": "./src/collection/btree.ts",
     "./collection/default-map": "./src/collection/default-map.ts",
     "./collection/iterables": "./src/collection/iterables.ts",
-    "./collection/maps": "./src/collection/maps.ts",
     "./collection/min-heap": "./src/collection/min-heap.ts",
     "./collection/multiset": "./src/collection/multiset.ts",
     "./collection/segment-tree": "./src/collection/segment-tree.ts",
@@ -20,17 +17,10 @@
     "./concurrency/deferred": "./src/concurrency/deferred.ts",
     "./concurrency/lazy-thenable": "./src/concurrency/lazy-thenable.ts",
     "./concurrency/lease": "./src/concurrency/lease.ts",
-    "./concurrency/lockable": "./src/concurrency/lockable.ts",
-    "./concurrency/promise-container": "./src/concurrency/promise-container.ts",
     "./concurrency/resource-pool": "./src/concurrency/resource-pool.ts",
     "./concurrency/tic-toc": "./src/concurrency/tic-toc.ts",
     "./concurrency/timing": "./src/concurrency/timing.ts",
-    "./event-emitter/typed-event-emitter": "./src/event-emitter/typed-event-emitter.ts",
     "./fp-ts/monoid": "./src/fp-ts/monoid.ts",
-    "./frontend/dummy-img": "./src/frontend/dummy-img.ts",
-    "./frontend/fps-observable": "./src/frontend/fps-observable.ts",
-    "./frontend/measure-img": "./src/frontend/measure-img.ts",
-    "./frontend/observe-dom-mutation": "./src/frontend/observe-dom-mutation.ts",
     "./index": "./src/index.ts",
     "./logging/console-logger": "./src/logging/console-logger.ts",
     "./logging/get-debug-namespace": "./src/logging/get-debug-namespace.ts",
@@ -39,6 +29,8 @@
     "./node/fsp": "./src/node/fsp.ts",
     "./node/index": "./src/node/index.ts",
     "./node/subprocess": "./src/node/subprocess.ts",
+    "./random/number": "./src/random/number.ts",
+    "./random/series": "./src/random/series.ts",
     "./react/component/font-awesome": "./src/react/component/font-awesome.tsx",
     "./react/component/inspect-render-count": "./src/react/component/inspect-render-count.tsx",
     "./react/component/pre-json": "./src/react/component/pre-json.tsx",
@@ -54,17 +46,21 @@
     "./react/hook/use-promised": "./src/react/hook/use-promised.ts",
     "./react/hook/use-versioned-memo": "./src/react/hook/use-versioned-memo.ts",
     "./react/mobx/use-derived": "./src/react/mobx/use-derived.ts",
+    "./react/mobx/use-mobx-derived": "./src/react/mobx/use-mobx-derived.ts",
     "./react/util/prop-of": "./src/react/util/prop-of.ts",
-    "./rxjs/distributions": "./src/rxjs/distributions.ts",
-    "./rxjs/stochastic-processes": "./src/rxjs/stochastic-processes.ts",
+    "./rxjs/poisson-observable": "./src/rxjs/poisson-observable.ts",
+    "./stress/chunk": "./src/stress/chunk.ts",
+    "./stress/groupBy": "./src/stress/groupBy.ts",
+    "./stress/sortBy": "./src/stress/sortBy.ts",
     "./text/chunk-to-lines": "./src/text/chunk-to-lines.ts",
     "./text/random-string": "./src/text/random-string.ts",
     "./type/freeze": "./src/type/freeze.ts",
     "./type/index": "./src/type/index.ts",
     "./type/omit": "./src/type/omit.ts",
-    "./util/lru": "./src/util/lru.ts",
-    "./util/proxys": "./src/util/proxys.ts",
-    "./util/randoms": "./src/util/randoms.ts",
-    "./util/with-retry": "./src/util/with-retry.ts"
+    "./util/with-retry": "./src/util/with-retry.ts",
+    "./web/dummy-img": "./src/web/dummy-img.ts",
+    "./web/fps-observable": "./src/web/fps-observable.ts",
+    "./web/measure-img": "./src/web/measure-img.ts",
+    "./web/observe-dom-mutation": "./src/web/observe-dom-mutation.ts"
   }
 }
\ No newline at end of file
diff --git a/obsolete/algebra/promise.spec.ts b/obsolete/algebra/promise.spec.ts
new file mode 100644
index 0000000..1abda42
--- /dev/null
+++ b/obsolete/algebra/promise.spec.ts
@@ -0,0 +1,9 @@
+import { liftA2 } from './promise';
+
+describe('liftA2', () => {
+    it('lifts a sync function to promise', async () => {
+        const liftedPlus = liftA2((a: number, b: number) => a + b);
+        const sum = await liftedPlus(3, Promise.resolve(5));
+        expect(sum).toEqual(8);
+    });
+});
diff --git a/obsolete/algebra/promise.ts b/obsolete/algebra/promise.ts
new file mode 100644
index 0000000..bf2e1cc
--- /dev/null
+++ b/obsolete/algebra/promise.ts
@@ -0,0 +1,13 @@
+
+/**
+ * lift2 f to Promise
+ */
+export function liftA2<T1, T2, T3>(f: (a1: T1, a2: T2) => T3) {
+    async function transformed(pa1: PromiseLike<T1> | T1, pa2: PromiseLike<T2> | T2): Promise<T3> {
+        const v1 = await pa1;
+        const v2 = await pa2;
+        return Promise.resolve(f(v1, v2));
+    }
+
+    return transformed;
+}
diff --git a/src/concurrency/promise-container.spec.ts b/obsolete/concurrency/promise-container.spec.ts
similarity index 96%
rename from src/concurrency/promise-container.spec.ts
rename to obsolete/concurrency/promise-container.spec.ts
index c362604..53de664 100644
--- a/src/concurrency/promise-container.spec.ts
+++ b/obsolete/concurrency/promise-container.spec.ts
@@ -1,6 +1,6 @@
 import { PromiseContainer, PromiseState } from './promise-container';
-import { wait } from './timing';
-import { TicToc } from './tic-toc';
+import { wait } from '../../src/concurrency/timing';
+import { TicToc } from '../../src/concurrency/tic-toc';
 
 describe('promise-container', () => {
   it('keeps promised value', async () => {
diff --git a/src/concurrency/promise-container.ts b/obsolete/concurrency/promise-container.ts
similarity index 98%
rename from src/concurrency/promise-container.ts
rename to obsolete/concurrency/promise-container.ts
index c791119..2a4861b 100644
--- a/src/concurrency/promise-container.ts
+++ b/obsolete/concurrency/promise-container.ts
@@ -1,4 +1,4 @@
-import { Doomed } from './timing';
+import { Doomed } from '../../src/concurrency/timing';
 
 export enum PromiseState {
   pending = 'pending',
diff --git a/obsolete/node/read-stream.ts b/obsolete/node/read-stream.ts
new file mode 100644
index 0000000..f253f7b
--- /dev/null
+++ b/obsolete/node/read-stream.ts
@@ -0,0 +1,22 @@
+/**
+ * Read stream until end
+ * @deprecated use 'node:stream/consumers' instead.
+ * @see https://nodejs.org/api/webstreams.html#streamconsumersjsonstream
+ */
+export function readStream(stream: NodeJS.ReadableStream | NodeJS.ReadStream): Promise<Buffer> {
+  return new Promise<Buffer>((resolve, reject) => {
+    const buffers = [] as Buffer[];
+
+    stream.once('end', () => resolve(Buffer.concat(buffers)));
+
+    stream.on('error', reject);
+
+    stream.on('data', (chunk: string | Buffer) => {
+      if (Buffer.isBuffer(chunk)) {
+        buffers.push(chunk);
+      } /* (typeof chunk === "string") */ else {
+        buffers.push(Buffer.from(chunk));
+      }
+    });
+  });
+}
diff --git a/package.json b/package.json
index 0b90cf5..169c8d2 100644
--- a/package.json
+++ b/package.json
@@ -47,6 +47,7 @@
     "fp-ts": "^2",
     "gts": "^5.2.0",
     "jest": "^29",
+    "jsr": "^0.12.4",
     "loglevel": "^1.8.0",
     "mobx": "^6.6.1",
     "react": "^18.2.0",
@@ -57,35 +58,25 @@
     "winston": "^3.8.0"
   },
   "exports": {
-    "./lib/algebra/monoid": {
-      "import": "./lib/__esm/algebra/monoid.js",
-      "require": "./lib/algebra/monoid.js",
-      "type": "./lib/algebra/monoid.d.ts"
-    },
     "./lib/algebra/topological-sort": {
       "import": "./lib/__esm/algebra/topological-sort.js",
       "require": "./lib/algebra/topological-sort.js",
       "type": "./lib/algebra/topological-sort.d.ts"
     },
-    "./lib/algebra/total-ordered": {
-      "import": "./lib/__esm/algebra/total-ordered.js",
-      "require": "./lib/algebra/total-ordered.js",
-      "type": "./lib/algebra/total-ordered.d.ts"
-    },
-    "./lib/binary-conversion/array-buffer": {
-      "import": "./lib/__esm/binary-conversion/array-buffer.js",
-      "require": "./lib/binary-conversion/array-buffer.js",
-      "type": "./lib/binary-conversion/array-buffer.d.ts"
+    "./lib/bytes/array-buffer": {
+      "import": "./lib/__esm/bytes/array-buffer.js",
+      "require": "./lib/bytes/array-buffer.js",
+      "type": "./lib/bytes/array-buffer.d.ts"
     },
-    "./lib/binary-conversion/string": {
-      "import": "./lib/__esm/binary-conversion/string.js",
-      "require": "./lib/binary-conversion/string.js",
-      "type": "./lib/binary-conversion/string.d.ts"
+    "./lib/bytes/string": {
+      "import": "./lib/__esm/bytes/string.js",
+      "require": "./lib/bytes/string.js",
+      "type": "./lib/bytes/string.d.ts"
     },
-    "./lib/binary-conversion/web": {
-      "import": "./lib/__esm/binary-conversion/web.js",
-      "require": "./lib/binary-conversion/web.js",
-      "type": "./lib/binary-conversion/web.d.ts"
+    "./lib/bytes/web": {
+      "import": "./lib/__esm/bytes/web.js",
+      "require": "./lib/bytes/web.js",
+      "type": "./lib/bytes/web.d.ts"
     },
     "./lib/collection/btree": {
       "import": "./lib/__esm/collection/btree.js",
@@ -102,11 +93,6 @@
       "require": "./lib/collection/iterables.js",
       "type": "./lib/collection/iterables.d.ts"
     },
-    "./lib/collection/maps": {
-      "import": "./lib/__esm/collection/maps.js",
-      "require": "./lib/collection/maps.js",
-      "type": "./lib/collection/maps.d.ts"
-    },
     "./lib/collection/min-heap": {
       "import": "./lib/__esm/collection/min-heap.js",
       "require": "./lib/collection/min-heap.js",
@@ -147,16 +133,6 @@
       "require": "./lib/concurrency/lease.js",
       "type": "./lib/concurrency/lease.d.ts"
     },
-    "./lib/concurrency/lockable": {
-      "import": "./lib/__esm/concurrency/lockable.js",
-      "require": "./lib/concurrency/lockable.js",
-      "type": "./lib/concurrency/lockable.d.ts"
-    },
-    "./lib/concurrency/promise-container": {
-      "import": "./lib/__esm/concurrency/promise-container.js",
-      "require": "./lib/concurrency/promise-container.js",
-      "type": "./lib/concurrency/promise-container.d.ts"
-    },
     "./lib/concurrency/resource-pool": {
       "import": "./lib/__esm/concurrency/resource-pool.js",
       "require": "./lib/concurrency/resource-pool.js",
@@ -172,36 +148,11 @@
       "require": "./lib/concurrency/timing.js",
       "type": "./lib/concurrency/timing.d.ts"
     },
-    "./lib/event-emitter/typed-event-emitter": {
-      "import": "./lib/__esm/event-emitter/typed-event-emitter.js",
-      "require": "./lib/event-emitter/typed-event-emitter.js",
-      "type": "./lib/event-emitter/typed-event-emitter.d.ts"
-    },
     "./lib/fp-ts/monoid": {
       "import": "./lib/__esm/fp-ts/monoid.js",
       "require": "./lib/fp-ts/monoid.js",
       "type": "./lib/fp-ts/monoid.d.ts"
     },
-    "./lib/frontend/dummy-img": {
-      "import": "./lib/__esm/frontend/dummy-img.js",
-      "require": "./lib/frontend/dummy-img.js",
-      "type": "./lib/frontend/dummy-img.d.ts"
-    },
-    "./lib/frontend/fps-observable": {
-      "import": "./lib/__esm/frontend/fps-observable.js",
-      "require": "./lib/frontend/fps-observable.js",
-      "type": "./lib/frontend/fps-observable.d.ts"
-    },
-    "./lib/frontend/measure-img": {
-      "import": "./lib/__esm/frontend/measure-img.js",
-      "require": "./lib/frontend/measure-img.js",
-      "type": "./lib/frontend/measure-img.d.ts"
-    },
-    "./lib/frontend/observe-dom-mutation": {
-      "import": "./lib/__esm/frontend/observe-dom-mutation.js",
-      "require": "./lib/frontend/observe-dom-mutation.js",
-      "type": "./lib/frontend/observe-dom-mutation.d.ts"
-    },
     "./lib/index": {
       "import": "./lib/__esm/index.js",
       "require": "./lib/index.js",
@@ -242,6 +193,16 @@
       "require": "./lib/node/subprocess.js",
       "type": "./lib/node/subprocess.d.ts"
     },
+    "./lib/random/number": {
+      "import": "./lib/__esm/random/number.js",
+      "require": "./lib/random/number.js",
+      "type": "./lib/random/number.d.ts"
+    },
+    "./lib/random/series": {
+      "import": "./lib/__esm/random/series.js",
+      "require": "./lib/random/series.js",
+      "type": "./lib/random/series.d.ts"
+    },
     "./lib/react/component/font-awesome": {
       "import": "./lib/__esm/react/component/font-awesome.jsx",
       "require": "./lib/react/component/font-awesome.jsx",
@@ -317,20 +278,35 @@
       "require": "./lib/react/mobx/use-derived.js",
       "type": "./lib/react/mobx/use-derived.d.ts"
     },
+    "./lib/react/mobx/use-mobx-derived": {
+      "import": "./lib/__esm/react/mobx/use-mobx-derived.js",
+      "require": "./lib/react/mobx/use-mobx-derived.js",
+      "type": "./lib/react/mobx/use-mobx-derived.d.ts"
+    },
     "./lib/react/util/prop-of": {
       "import": "./lib/__esm/react/util/prop-of.js",
       "require": "./lib/react/util/prop-of.js",
       "type": "./lib/react/util/prop-of.d.ts"
     },
-    "./lib/rxjs/distributions": {
-      "import": "./lib/__esm/rxjs/distributions.js",
-      "require": "./lib/rxjs/distributions.js",
-      "type": "./lib/rxjs/distributions.d.ts"
+    "./lib/rxjs/poisson-observable": {
+      "import": "./lib/__esm/rxjs/poisson-observable.js",
+      "require": "./lib/rxjs/poisson-observable.js",
+      "type": "./lib/rxjs/poisson-observable.d.ts"
+    },
+    "./lib/stress/chunk": {
+      "import": "./lib/__esm/stress/chunk.js",
+      "require": "./lib/stress/chunk.js",
+      "type": "./lib/stress/chunk.d.ts"
+    },
+    "./lib/stress/groupBy": {
+      "import": "./lib/__esm/stress/groupBy.js",
+      "require": "./lib/stress/groupBy.js",
+      "type": "./lib/stress/groupBy.d.ts"
     },
-    "./lib/rxjs/stochastic-processes": {
-      "import": "./lib/__esm/rxjs/stochastic-processes.js",
-      "require": "./lib/rxjs/stochastic-processes.js",
-      "type": "./lib/rxjs/stochastic-processes.d.ts"
+    "./lib/stress/sortBy": {
+      "import": "./lib/__esm/stress/sortBy.js",
+      "require": "./lib/stress/sortBy.js",
+      "type": "./lib/stress/sortBy.d.ts"
     },
     "./lib/text/chunk-to-lines": {
       "import": "./lib/__esm/text/chunk-to-lines.js",
@@ -357,29 +333,34 @@
       "require": "./lib/type/omit.js",
       "type": "./lib/type/omit.d.ts"
     },
-    "./lib/util/lru": {
-      "import": "./lib/__esm/util/lru.js",
-      "require": "./lib/util/lru.js",
-      "type": "./lib/util/lru.d.ts"
-    },
-    "./lib/util/proxys": {
-      "import": "./lib/__esm/util/proxys.js",
-      "require": "./lib/util/proxys.js",
-      "type": "./lib/util/proxys.d.ts"
-    },
-    "./lib/util/randoms": {
-      "import": "./lib/__esm/util/randoms.js",
-      "require": "./lib/util/randoms.js",
-      "type": "./lib/util/randoms.d.ts"
-    },
     "./lib/util/with-retry": {
       "import": "./lib/__esm/util/with-retry.js",
       "require": "./lib/util/with-retry.js",
       "type": "./lib/util/with-retry.d.ts"
+    },
+    "./lib/web/dummy-img": {
+      "import": "./lib/__esm/web/dummy-img.js",
+      "require": "./lib/web/dummy-img.js",
+      "type": "./lib/web/dummy-img.d.ts"
+    },
+    "./lib/web/fps-observable": {
+      "import": "./lib/__esm/web/fps-observable.js",
+      "require": "./lib/web/fps-observable.js",
+      "type": "./lib/web/fps-observable.d.ts"
+    },
+    "./lib/web/measure-img": {
+      "import": "./lib/__esm/web/measure-img.js",
+      "require": "./lib/web/measure-img.js",
+      "type": "./lib/web/measure-img.d.ts"
+    },
+    "./lib/web/observe-dom-mutation": {
+      "import": "./lib/__esm/web/observe-dom-mutation.js",
+      "require": "./lib/web/observe-dom-mutation.js",
+      "type": "./lib/web/observe-dom-mutation.d.ts"
     }
   },
   "resolutions": {
     "@types/node": "18",
     "@types/react": "^18"
   }
-}
\ No newline at end of file
+}
diff --git a/src/binary-conversion/array-buffer.ts b/src/bytes/array-buffer.ts
similarity index 100%
rename from src/binary-conversion/array-buffer.ts
rename to src/bytes/array-buffer.ts
diff --git a/src/binary-conversion/string.ts b/src/bytes/string.ts
similarity index 100%
rename from src/binary-conversion/string.ts
rename to src/bytes/string.ts
diff --git a/src/binary-conversion/web.ts b/src/bytes/web.ts
similarity index 100%
rename from src/binary-conversion/web.ts
rename to src/bytes/web.ts
diff --git a/src/concurrency/deferred.ts b/src/concurrency/deferred.ts
index 0e4f4ff..65043a7 100644
--- a/src/concurrency/deferred.ts
+++ b/src/concurrency/deferred.ts
@@ -19,7 +19,7 @@ export class Deferred<T> implements PromiseLike<T> {
     return d;
   }
 
-  private readonly _promise = new Promise<T>((fulfill, reject) => {
+  readonly #promise = new Promise<T>((fulfill, reject) => {
     this.#fulfill = (v: T | PromiseLike<T>) => {
       fulfill(v);
       this.#resolved = true;
@@ -38,7 +38,7 @@ export class Deferred<T> implements PromiseLike<T> {
     return this.#resolved;
   }
 
-  readonly then = this._promise.then.bind(this._promise);
+  readonly then = this.#promise.then.bind(this.#promise);
 
   /**
    * @param v the value
diff --git a/src/concurrency/lockable.ts b/src/concurrency/lockable.ts
deleted file mode 100644
index e69de29..0000000
diff --git a/src/node/fsp.ts b/src/node/fsp.ts
index e04cc55..9ed8fc9 100644
--- a/src/node/fsp.ts
+++ b/src/node/fsp.ts
@@ -1,4 +1,4 @@
-import { promises as fsPromised } from 'fs';
+import fsPromised from 'node:fs/promises';
 import { chunkToLines } from '../text/chunk-to-lines';
 
 export const readText = (filename: string, encoding: BufferEncoding = 'utf-8'): Promise<string> =>
diff --git a/src/node/index.ts b/src/node/index.ts
index a97ee58..81dc3d3 100644
--- a/src/node/index.ts
+++ b/src/node/index.ts
@@ -1,29 +1,3 @@
-/**
- * Read stream until end
- * @deprecated use 'node:stream/consumers' instead.
- * @see https://nodejs.org/api/webstreams.html#streamconsumersjsonstream
- */
-export function readStream(stream: NodeJS.ReadableStream): Promise<Buffer> {
-  return new Promise<Buffer>((resolve, reject) => {
-    const buffers = [] as Buffer[];
-
-    stream.once('end', () => resolve(Buffer.concat(buffers)));
-
-    stream.on('error', reject);
-
-    stream.on('data', (chunk: string | Buffer) => {
-      if (Buffer.isBuffer(chunk)) {
-        buffers.push(chunk);
-      } /* (typeof chunk === "string") */ else {
-        buffers.push(Buffer.from(chunk));
-      }
-    });
-  });
-}
-
-/**
- * @deprecated use 'node:fs/promises' instead.
- */
 import * as fsp from './fsp';
 
 export { fsp };
diff --git a/src/random/number.ts b/src/random/number.ts
new file mode 100644
index 0000000..535abd8
--- /dev/null
+++ b/src/random/number.ts
@@ -0,0 +1,30 @@
+export const defaultRng = Math.random;
+
+function sample<T>(from: ReadonlyArray<T>, count: number, rng = defaultRng): T[] {
+  const sampled: T[] = from.slice(0, count); // 'reservoir'
+
+  for (let i = count; i < from.length; i++) {
+    const j = Math.floor(1 + Math.random() * i);
+    if (j < count) {
+      sampled[j] = from[i];
+    }
+  }
+
+  return sampled;
+}
+
+export function binomialRandom(n: number, p: number, rng = defaultRng): number {
+  let s = 0;
+  for (let sample = 0; sample < n; ++sample) {
+    if (rng() <= p) ++s;
+  }
+  return s;
+}
+
+export function gaussianRandom(rng = defaultRng): number {
+  const u1 = rng(),
+    u2 = rng();
+
+  // basic form of Box-Muller transform
+  return Math.sqrt(-2 * Math.log(u1)) * Math.cos(2 * Math.PI * u2);
+}
diff --git a/src/random/series.ts b/src/random/series.ts
new file mode 100644
index 0000000..4f9e1a3
--- /dev/null
+++ b/src/random/series.ts
@@ -0,0 +1,14 @@
+import { defaultRng, gaussianRandom } from './number';
+
+export function* bernoulliSeries(p: number, rng = defaultRng): Generator<boolean, void> {
+  while (true) yield rng() < p;
+}
+
+export function* wienerSeries(dt: number, rng = defaultRng): Generator<number, void> {
+  let sum = 0;
+  yield sum;
+  while (true) {
+    const d = Math.sqrt(dt) * gaussianRandom(rng);
+    yield (sum += d);
+  }
+}
diff --git a/src/react/component/inspect-render-count.tsx b/src/react/component/inspect-render-count.tsx
index 54c5731..d8eb3e6 100644
--- a/src/react/component/inspect-render-count.tsx
+++ b/src/react/component/inspect-render-count.tsx
@@ -6,7 +6,7 @@ import {
   MutationCounts,
   resolveHTMLElement,
   startObserve,
-} from '../../frontend/observe-dom-mutation';
+} from '../../web/observe-dom-mutation';
 
 export const RenderCountsToWidget: React.FC<MutationCounts> = (counter) => (
   <>
diff --git a/src/react/component/pre-json.tsx b/src/react/component/pre-json.tsx
index 531568b..fdb8d76 100644
--- a/src/react/component/pre-json.tsx
+++ b/src/react/component/pre-json.tsx
@@ -1,4 +1,4 @@
-import React from 'react';
+import type React from 'react';
 
 export const PreJson: React.FunctionComponent<{ value: any }> = ({ value }) => {
   return <pre>{JSON.stringify(value, null, 2)}</pre>;
diff --git a/src/react/hook/use-fps.ts b/src/react/hook/use-fps.ts
index 41d6b54..6fa67c1 100644
--- a/src/react/hook/use-fps.ts
+++ b/src/react/hook/use-fps.ts
@@ -1,5 +1,5 @@
 import { useMemo } from 'react';
-import { createFpsObservable } from '../../frontend/fps-observable';
+import { createFpsObservable } from '../../web/fps-observable';
 import { useExternalObservable } from './use-observable-store';
 
 export function useFps(windowSize: number): number {
diff --git a/src/react/hook/use-observable-store.ts b/src/react/hook/use-observable-store.ts
index 122b329..f8924b0 100644
--- a/src/react/hook/use-observable-store.ts
+++ b/src/react/hook/use-observable-store.ts
@@ -1,4 +1,4 @@
-import { Observable } from 'rxjs';
+import type { Observable } from 'rxjs';
 import { useDeferredValue, useEffect, useRef, useState, useSyncExternalStore, useTransition } from 'react';
 
 export function useExternalObservable<T>(observable: Observable<T>, defaultValue: T): T {
diff --git a/src/react/util/prop-of.ts b/src/react/util/prop-of.ts
index d820742..81f4be2 100644
--- a/src/react/util/prop-of.ts
+++ b/src/react/util/prop-of.ts
@@ -1,3 +1,3 @@
 import * as React from 'react';
 
-export type PropOf<T extends React.ComponentType<any>> = T extends React.ComponentType<infer P> ? P : never;
+export type PropOf<T extends React.ComponentType<any>> = T extends React.ComponentType<infer P> ? P : unknown;
diff --git a/src/rxjs/distributions.ts b/src/rxjs/distributions.ts
deleted file mode 100644
index 7508967..0000000
--- a/src/rxjs/distributions.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-export function binomialRandom(n: number, p: number): number {
-  let s = 0;
-  for (let sample = 0; sample < n; ++sample) {
-    if (Math.random() <= p) ++s;
-  }
-  return s;
-}
-
-export function gaussianRandom(): number {
-  const u1 = Math.random(),
-    u2 = Math.random();
-
-  // basic form of Box-Muller transform
-  return Math.sqrt(-2 * Math.log(u1)) * Math.cos(2 * Math.PI * u2);
-}
diff --git a/src/rxjs/poisson-observable.ts b/src/rxjs/poisson-observable.ts
new file mode 100644
index 0000000..a429e7f
--- /dev/null
+++ b/src/rxjs/poisson-observable.ts
@@ -0,0 +1,31 @@
+import { Observable, Subscriber } from 'rxjs';
+import { wait } from '../concurrency/timing';
+import { defaultRng } from '../random/number';
+
+/**
+ * @param {number} lambda expected occurrence rate in {@code $ s^{-1} $ }
+ * @param rng random number generator
+ * @returns A cold observable that emits 0-based integers, at Poissonic random interval
+ */
+export function poissonObservable(lambda = 1, rng = defaultRng): Observable<number> {
+  return new Observable<number>((subscriber) => {
+    setTimeout(() => postPoissonEvents(subscriber, lambda, () => subscriber.closed));
+  });
+}
+/**
+ * @internal
+ */
+async function postPoissonEvents(
+  subscriber: Subscriber<number>,
+  lambda: number,
+  shouldStop: () => boolean,
+  rng = defaultRng,
+): Promise<void> {
+  let eventNo = 0;
+  while (true) {
+    const poissonDelay = (-1 / lambda) * Math.log(rng()) * 1e3;
+    await wait(poissonDelay);
+    if (shouldStop()) break;
+    subscriber.next(eventNo++);
+  }
+}
diff --git a/src/rxjs/stochastic-processes.ts b/src/rxjs/stochastic-processes.ts
deleted file mode 100644
index f9b5067..0000000
--- a/src/rxjs/stochastic-processes.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-import { Observable, from, Subscriber } from 'rxjs';
-import { gaussianRandom } from './distributions';
-import { wait } from '../concurrency/timing';
-
-export function bernoulli(p: number): Observable<boolean> {
-  return from(bernoulliIterator(p));
-}
-
-/**
- * @internal
- * @param p
- */
-function* bernoulliIterator(p: number) {
-  while (true) yield Math.random() < p;
-}
-
-/**
- * @internal
- * @param dt
- */
-export function wiener(dt = 1): Observable<number> {
-  return from(wienerIterator(dt));
-}
-
-function* wienerIterator(dt: number) {
-  let sum = 0;
-  yield sum;
-  while (true) {
-    const d = Math.sqrt(dt) * gaussianRandom();
-    yield (sum += d);
-  }
-}
-
-/**
- * @param {number} lambda expected occurrence rate in {@code $ s^{-1} $ }
- * @returns {Observable<number>} A observable that emits 0-based integers at Poissonic random interval
- */
-export function poisson(lambda = 1): Observable<number> {
-  return new Observable<number>((subscriber) => {
-    setTimeout(() => postPoissonEvents(subscriber, lambda, () => subscriber.closed));
-  });
-}
-
-/**
- * @internal
- */
-async function postPoissonEvents(
-  subscriber: Subscriber<number>,
-  lambda: number,
-  shouldStop: () => boolean,
-): Promise<void> {
-  let eventNo = 0;
-  while (true) {
-    const poissonDelay = (-1 / lambda) * Math.log(Math.random()) * 1e3;
-    await wait(poissonDelay);
-    if (shouldStop()) break;
-    subscriber.next(eventNo++);
-  }
-}
diff --git a/src/type/index.ts b/src/type/index.ts
index ef184bf..7bd710a 100644
--- a/src/type/index.ts
+++ b/src/type/index.ts
@@ -2,16 +2,3 @@
  * Type transformers and etc
  */
 export * from './freeze';
-
-/**
- * lift2 f to Promise
- */
-export function liftA2<T1, T2, T3>(f: (a1: T1, a2: T2) => T3) {
-  async function transformed(pa1: PromiseLike<T1> | T1, pa2: PromiseLike<T2> | T2): Promise<T3> {
-    const v1 = await pa1;
-    const v2 = await pa2;
-    return Promise.resolve(f(v1, v2));
-  }
-
-  return transformed;
-}
diff --git a/src/type/type.spec.ts b/src/type/type.spec.ts
deleted file mode 100644
index 7de1ee9..0000000
--- a/src/type/type.spec.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-import { liftA2 } from './index';
-
-describe('liftA2', () => {
-  it('lifts a sync function to promise', async () => {
-    const liftedPlus = liftA2((a: number, b: number) => a + b);
-    const sum = await liftedPlus(3, Promise.resolve(5));
-    expect(sum).toEqual(8);
-  });
-});
diff --git a/src/util/proxys.ts b/src/util/proxys.ts
deleted file mode 100644
index 3eef599..0000000
--- a/src/util/proxys.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-export const Proxies = {
-  // eslint-disable-next-line @typescript-eslint/ban-types
-  revoked<T extends object>(): T {
-    const { proxy, revoke } = Proxy.revocable<T>({} as any, {});
-    revoke();
-    return proxy;
-  },
-} as const;
diff --git a/src/util/randoms.ts b/src/util/randoms.ts
deleted file mode 100644
index df621d0..0000000
--- a/src/util/randoms.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-function sample<T>(from: ReadonlyArray<T>, count: number): T[] {
-  const sampled: T[] = from.slice(0, count); // 'reservoir'
-
-  for (let i = count; i < from.length; i++) {
-    const j = Math.floor(1 + Math.random() * i);
-    if (j < count) {
-      sampled[j] = from[i];
-    }
-  }
-
-  return sampled;
-}
diff --git a/src/frontend/dummy-img.ts b/src/web/dummy-img.ts
similarity index 100%
rename from src/frontend/dummy-img.ts
rename to src/web/dummy-img.ts
diff --git a/src/frontend/fps-observable.ts b/src/web/fps-observable.ts
similarity index 100%
rename from src/frontend/fps-observable.ts
rename to src/web/fps-observable.ts
diff --git a/src/frontend/measure-img.ts b/src/web/measure-img.ts
similarity index 100%
rename from src/frontend/measure-img.ts
rename to src/web/measure-img.ts
diff --git a/src/frontend/observe-dom-mutation.ts b/src/web/observe-dom-mutation.ts
similarity index 100%
rename from src/frontend/observe-dom-mutation.ts
rename to src/web/observe-dom-mutation.ts
diff --git a/yarn.lock b/yarn.lock
index 06e61c8..9b52c24 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2430,6 +2430,15 @@ json5@^2.1.3, json5@^2.2.3:
   resolved "https://registry.yarnpkg.com/json5/-/json5-2.2.3.tgz#78cd6f1a19bdc12b73db5ad0c61efd66c1e29283"
   integrity sha512-XmOWe7eyHYH14cLdVPoyg+GOH3rYX++KpzrylJwSW98t3Nk+U8XOl8FWKOgwtzdb8lXGf6zYwDUzeHMWfxasyg==
 
+jsr@^0.12.4:
+  version "0.12.4"
+  resolved "https://registry.yarnpkg.com/jsr/-/jsr-0.12.4.tgz#f353cf10f9dadf147528c7be56bf38db51536b69"
+  integrity sha512-ZWDvqQE8014fWz9QBrkiuvRQ8mH97PRD13VIDzoMXDem3ff2S+wfXw+YAvrZE0aKzxh9FuHJX0HQRQ2MUHshig==
+  dependencies:
+    kolorist "^1.8.0"
+    node-stream-zip "^1.15.0"
+    semiver "^1.1.0"
+
 keyv@^4.5.3:
   version "4.5.4"
   resolved "https://registry.yarnpkg.com/keyv/-/keyv-4.5.4.tgz#a879a99e29452f942439f2a405e3af8b31d4de93"
@@ -2447,6 +2456,11 @@ kleur@^3.0.3:
   resolved "https://registry.yarnpkg.com/kleur/-/kleur-3.0.3.tgz#a79c9ecc86ee1ce3fa6206d1216c501f147fc07e"
   integrity sha512-eTIzlVOSUR+JxdDFepEYcBMtZ9Qqdef+rnzWdRZuMbOywu5tO2w2N7rqjoANZ5k9vywhL6Br1VRjUIgTQx4E8w==
 
+kolorist@^1.8.0:
+  version "1.8.0"
+  resolved "https://registry.yarnpkg.com/kolorist/-/kolorist-1.8.0.tgz#edddbbbc7894bc13302cdf740af6374d4a04743c"
+  integrity sha512-Y+60/zizpJ3HRH8DCss+q95yr6145JXZo46OTpFvDZWLfRCE4qChOyk1b26nMaNpfHHgxagk9dXT5OP0Tfe+dQ==
+
 kuler@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/kuler/-/kuler-2.0.0.tgz#e2c570a3800388fb44407e851531c1d670b061b3"
@@ -2673,6 +2687,11 @@ node-releases@^2.0.14:
   resolved "https://registry.yarnpkg.com/node-releases/-/node-releases-2.0.14.tgz#2ffb053bceb8b2be8495ece1ab6ce600c4461b0b"
   integrity sha512-y10wOWt8yZpqXmOgRo77WaHEmhYQYGNA6y421PKsKYWEK8aW+cqAphborZDhqfyKrbZEN92CN1X2KbafY2s7Yw==
 
+node-stream-zip@^1.15.0:
+  version "1.15.0"
+  resolved "https://registry.yarnpkg.com/node-stream-zip/-/node-stream-zip-1.15.0.tgz#158adb88ed8004c6c49a396b50a6a5de3bca33ea"
+  integrity sha512-LN4fydt9TqhZhThkZIVQnF9cwjU3qmUH9h78Mx/K7d3VvfRqqwthLwJEUOEL0QPZ0XQmNN7be5Ggit5+4dq3Bw==
+
 normalize-package-data@^2.5.0:
   version "2.5.0"
   resolved "https://registry.yarnpkg.com/normalize-package-data/-/normalize-package-data-2.5.0.tgz#e66db1838b200c1dfc233225d12cb36520e234a8"
@@ -3059,6 +3078,11 @@ scheduler@^0.23.0:
   dependencies:
     loose-envify "^1.1.0"
 
+semiver@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/semiver/-/semiver-1.1.0.tgz#9c97fb02c21c7ce4fcf1b73e2c7a24324bdddd5f"
+  integrity sha512-QNI2ChmuioGC1/xjyYwyZYADILWyW6AmS1UH6gDj/SFUUUS4MBAWs/7mxnkRPc/F4iHezDP+O8t0dO8WHiEOdg==
+
 "semver@2 || 3 || 4 || 5":
   version "5.7.2"
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.7.2.tgz#48d55db737c3287cd4835e17fa13feace1c41ef8"