move hs2js package here + improve readme

packages/hs2js/src/parser.mjs

@@ -0,0 +1,37 @@
+import Parser from "web-tree-sitter";
+
+let base = "/";
+export function setBase(path) {
+  base = path;
+}
+
+async function _loadParser() {
+  await Parser.init({
+    locateFile(scriptName, scriptDirectory) {
+      return `${base}${scriptName}`;
+    },
+  });
+  const parser = new Parser();
+  const Lang = await Parser.Language.load(`${base}tree-sitter-haskell.wasm`);
+  parser.setLanguage(Lang);
+  return parser;
+}
+
+let parserLoaded;
+export function loadParser() {
+  if (!parserLoaded) {
+    parserLoaded = _loadParser();
+  }
+  return parserLoaded;
+}
+
+export async function parse(code) {
+  const parser = await loadParser();
+  // for some reason, the parser doesn't like new lines..
+  return parser.parse(
+    code
+      .replaceAll("\n\n", "~~~~")
+      .replaceAll("\n", "")
+      .replaceAll("~~~~", "\n")
+  );
+}