From 8dcc1dfc1d19eb80180a4985e488b822acf2012b Mon Sep 17 00:00:00 2001
From: Michael Arnaldi <arnaldimichael@gmail.com>
Date: Thu, 25 Aug 2022 12:13:23 +0000
Subject: [PATCH] chore: add Ord.tuple

---
 .changeset/heavy-steaks-hope.md           |  5 +++++
 packages/stdlib/_src/prelude/Ord.ts       |  1 +
 packages/stdlib/_src/prelude/Ord/tuple.ts | 27 +++++++++++++++++++++++
 3 files changed, 33 insertions(+)
 create mode 100644 .changeset/heavy-steaks-hope.md
 create mode 100644 packages/stdlib/_src/prelude/Ord/tuple.ts

diff --git a/.changeset/heavy-steaks-hope.md b/.changeset/heavy-steaks-hope.md
new file mode 100644
index 00000000..714b48e7
--- /dev/null
+++ b/.changeset/heavy-steaks-hope.md
@@ -0,0 +1,5 @@
+---
+"@tsplus/stdlib": patch
+---
+
+Add Ord.tuple
diff --git a/packages/stdlib/_src/prelude/Ord.ts b/packages/stdlib/_src/prelude/Ord.ts
index 145ab995..8e2f8022 100644
--- a/packages/stdlib/_src/prelude/Ord.ts
+++ b/packages/stdlib/_src/prelude/Ord.ts
@@ -5,4 +5,5 @@ export * from "@tsplus/stdlib/prelude/Ord/definition"
 export * from "@tsplus/stdlib/prelude/Ord/getAssociative"
 export * from "@tsplus/stdlib/prelude/Ord/getAssociativeIdentity"
 export * from "@tsplus/stdlib/prelude/Ord/operations"
+export * from "@tsplus/stdlib/prelude/Ord/tuple"
 // codegen:end
diff --git a/packages/stdlib/_src/prelude/Ord/tuple.ts b/packages/stdlib/_src/prelude/Ord/tuple.ts
new file mode 100644
index 00000000..b64811d2
--- /dev/null
+++ b/packages/stdlib/_src/prelude/Ord/tuple.ts
@@ -0,0 +1,27 @@
+export type NonEmptyArrayOrd = Array<Ord<any>> & { readonly 0: Ord<any> }
+
+export type TupleOrd<T extends NonEmptyArrayOrd> = {
+  [K in keyof T]: [T[K]] extends [Ord<infer A>] ? A : never
+}
+
+/**
+ * Derives an Ord instance for a tuple
+ *
+ * @tsplus static Ord/Ops tuple
+ */
+export function tuple<T extends NonEmptyArrayOrd>(
+  ...ords: T & {
+    readonly 0: Ord<any>
+  }
+): Ord<ForcedTuple<TupleOrd<T>>> {
+  return Ord((first, second) => {
+    let i = 0
+    for (; i < ords.length - 1; i++) {
+      const r = ords[i]!.compare(first[i], second[i])
+      if (r !== 0) {
+        return r
+      }
+    }
+    return ords[i]!.compare(first[i], second[i])
+  })
+}