DRAFT: implement sequence

src/sequence/minByOrNull.ts

@@ -0,0 +1,14 @@
+export function minByOrNull<T>(value: Iterable<T>, transform: (it: T) => number): T | null {
+    let minIt!: T;
+    let min!: number;
+    let found = false;
+    for (const it of value) {
+        const val = transform(it);
+        if (found && val >= min) continue;
+        minIt = it;
+        min = val;
+        found = true;
+    }
+    if (!found) return null;
+    return minIt;
+}