diff --git a/evaluator.ts b/evaluator.ts
new file mode 100644
index 0000000..34982a5
--- /dev/null
+++ b/evaluator.ts
@@ -0,0 +1,18 @@
+import type Card from './card';
+import Pile from './pile'
+import type Rule from './rules/rule';
+
+export type winner = {
+  index: number,
+  hand: Card[]
+}
+
+export default function(piles: Pile[], rule: Rule): winner | null {
+  if (piles.length < 1) return null
+
+  return piles.reduce((accumulator: winner, pile: Pile) => {
+    const priorPile = new Pile(accumulator.hand)
+    const priorPileEvaluated = rule(priorPile)
+    const pileEvaluated = rule(pile)
+  }, { index: -1, hand: [] })
+}
diff --git a/rules/highcard.test.ts b/rules/highcard.test.ts
new file mode 100644
index 0000000..38aec31
--- /dev/null
+++ b/rules/highcard.test.ts
@@ -0,0 +1,40 @@
+import { expect, test } from 'bun:test'
+import ruleHighcard from './highcard'
+import Pile from '../pile'
+import Card, { Index, Suit } from '../card'
+
+test('Ten beats One', () => {
+  const cardTen = new Card(Index.Ten, Suit.Club)
+  const cardOne = new Card(Index.One, Suit.Club)
+
+  const pile = new Pile([cardTen, cardOne])
+  expect(ruleHighcard(pile)).toBe(cardTen)
+
+  // Ensure it isn't just lucky ordering
+  const pileFlipped = new Pile([cardOne, cardTen])
+  expect(ruleHighcard(pileFlipped)).toBe(cardTen)
+})
+
+test('Ace beats King', () => {
+  const cardAce = new Card(Index.Ace, Suit.Club)
+  const cardKing = new Card(Index.King, Suit.Club)
+
+  const pile = new Pile([cardAce, cardKing])
+  expect(ruleHighcard(pile)).toBe(cardAce)
+
+  // Ensure it isn't just lucky ordering
+  const pileFlipped = new Pile([cardKing, cardAce])
+  expect(ruleHighcard(pileFlipped)).toBe(cardAce)
+})
+
+test('two hands compared for a winner', () => {
+  const cardAce = new Card(Index.Ace, Suit.Club)
+  const cardKing = new Card(Index.King, Suit.Club)
+  const cardTwo = new Card(Index.Two, Suit.Club)
+  const cardOne = new Card(Index.One, Suit.Club)
+  const hand1 = new Pile([cardAce, cardKing])
+  const hand2 = new Pile([cardOne, cardTwo])
+
+  expect(ruleHighcard(hand1)).toBe(cardAce)
+  expect(ruleHighcard(hand2)).toBe(cardTwo)
+})
diff --git a/rules/highcard.ts b/rules/highcard.ts
new file mode 100644
index 0000000..c9fe80e
--- /dev/null
+++ b/rules/highcard.ts
@@ -0,0 +1,15 @@
+import type Rule from './rule'
+import Card from '../card'
+
+let rule: Rule
+rule = function(pile) {
+  if (pile.cards.length < 1) return null
+
+  return pile
+    .cards
+    .reduce((accumulator: Card, card: Card) => {
+      if (card.decimalIndex > accumulator.decimalIndex) return card
+      return accumulator
+    }, pile.cards[0] as Card)
+}
+export default rule
diff --git a/rules/rule.ts b/rules/rule.ts
new file mode 100644
index 0000000..c3a1eb9
--- /dev/null
+++ b/rules/rule.ts
@@ -0,0 +1,7 @@
+import Pile from '../pile'
+import Card from '../card'
+
+export default interface Rule {
+  (pile: Pile): Card | null
+}
+