From 67bee5c0982d35f0d6a1350e002b7062a498afe7 Mon Sep 17 00:00:00 2001
From: Spotandjake <40705786+spotandjake@users.noreply.github.com>
Date: Sat, 4 Mar 2023 18:40:45 -0500
Subject: [PATCH] feat(stdlib)!: Add optimization for `Number.pow(Rational,
 Int)` (#1716)

* feat!: Add Optimization for `Rationional^Int`

* Update stdlib/runtime/numbers.gr

---------

Co-authored-by: Oscar Spencer <oscar.spen@gmail.com>
---
 compiler/test/stdlib/number.test.gr |  5 +++++
 stdlib/runtime/numbers.gr           | 23 ++++++++++++++++++++---
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/compiler/test/stdlib/number.test.gr b/compiler/test/stdlib/number.test.gr
index 2d6cd929a..8bcb4a20d 100644
--- a/compiler/test/stdlib/number.test.gr
+++ b/compiler/test/stdlib/number.test.gr
@@ -217,6 +217,11 @@ assert Number.pow(10223372036854775809, 10) ==
   12472159440978016923768615307032788210916694000775261660538874886865415760948494778813645195039710006678013364969179502650466497057008288260604039903029954443675868581729857084924132550246401
 assert Number.pow(1, 9223372036854775809) == 1
 assert Number.pow(2.0, 9223372036854775809) == Infinity
+assert Number.pow(1/2, 2) == 1/4
+assert Number.pow(1/2, 3) == 1/8
+assert Number.isRational(Number.pow(1/2, 2))
+assert Number.isRational(Number.pow(1/2, 3))
+assert Number.pow(1/2, -2) == 4
 // exp
 assert Number.exp(1) == 2.718281828459045
 assert Number.exp(10) == 22026.465794806703
diff --git a/stdlib/runtime/numbers.gr b/stdlib/runtime/numbers.gr
index 1cb22ea06..e1c5caa33 100644
--- a/stdlib/runtime/numbers.gr
+++ b/stdlib/runtime/numbers.gr
@@ -2803,13 +2803,30 @@ let rec expBySquaring = (y, x, n) => {
 provide let (**) = (base, power) => {
   let (==) = numberEq
   let (!=) = (x, y) => !numberEq(x, y)
+  let basePtr = WasmI32.fromGrain(base)
+  let powerPtr = WasmI32.fromGrain(power)
   if (base == 1 && power != 0) {
     return 1
-  } else if (
-    isInteger(WasmI32.fromGrain(base)) && isInteger(WasmI32.fromGrain(power))
-  ) {
+  } else if (isInteger(basePtr) && isInteger(powerPtr)) {
     if (power < 0) return expBySquaring(1, 1 / base, power * -1)
     else return expBySquaring(1, base, power)
+  } else if (isRational(basePtr) && isInteger(powerPtr)) {
+    // Apply expBySquaring to numerator and denominator
+    let numerator = WasmI32.fromGrain(base)
+    Memory.incRef(numerator)
+    let numerator = WasmI32.toGrain(numerator): Rational
+    let numerator = rationalNumerator(numerator)
+    let denominator = WasmI32.fromGrain(base)
+    Memory.incRef(denominator)
+    let denominator = WasmI32.toGrain(denominator): Rational
+    let denominator = rationalDenominator(denominator)
+    let numerator =
+      if (power < 0) expBySquaring(1, 1 / numerator, power * -1)
+      else expBySquaring(1, numerator, power)
+    let denominator =
+      if (power < 0) expBySquaring(1, 1 / denominator, power * -1)
+      else expBySquaring(1, denominator, power)
+    return numerator / denominator
   } else {
     // Based on https://git.musl-libc.org/cgit/musl/tree/src/math/pow.c
     from WasmF64 use {