move hs2js package here + improve readme

packages/hs2js/README.md

@@ -0,0 +1,49 @@
+# hs2js
+
+Experimental haskell in javascript interpreter.
+
+## Usage
+
+### Via Script Tag
+
+You can load the library directly from a script tag via unpkg:
+
+```html
+<script src="https://unpkg.com/hs2js@0.0.3"></script>
+<button id="hello">hello</button>
+<script>
+  hs2js.setBase('https://unpkg.com/hs2js@0.0.3/dist/');
+  hs2js.loadParser();
+  document.getElementById('hello').addEventListener('click', () => {
+    hs2js.evaluate('alert "hello from haskell!"');
+  });
+</script>
+```
+
+### Via npm
+
+You need to add `postinstall` to your `package.json` script to copy the parser to your `public` folder:
+
+```json
+{
+  "scripts": {
+    "postinstall": "cp node_modules/hs2js/dist/tree-sitter.wasm public && cp node_modules/hs2js/dist/tree-sitter-haskell.wasm public"
+  }
+}
+```
+
+Depending on your setup, replace `public` with the folder that will serve your assets to `/`. Then install the package:
+
+```sh
+npm i hs2js
+```
+
+and use it:
+
+```js
+import * as hs2js from 'hs2js';
+hs2js.loadParser();
+document.getElementById('hello').addEventListener('click', () => {
+  hs2js.evaluate('alert "hello from haskell!"');
+});
+```