Hello Typescript!

hydro/lib/rank.ts

@@ -0,0 +1,14 @@
+function* ranked(diter, equ = (a, b) => a === b) {
+    let last = null;
+    let r = 0;
+    let count = 0;
+    for (const doc of diter) {
+        count++;
+        if (count === 1 || !equ(last, doc)) r = count;
+        last = doc;
+        yield [r, doc];
+    }
+}
+
+global.Hydro.lib.rank = ranked;
+export default ranked;