feat(stdlib): Add ** operator to Int64 module (#1937)

Author: spotandjake

compiler/test/stdlib/int64.test.gr

@@ -65,3 +65,31 @@ from Pervasives use { (==) }
 // Regression #1339
 let arr = [> 1, 2, 3]
 assert arr[toNumber(1L)] == 2
+
+// pow
+assert 0L ** 3L == 0L
+assert 0L ** 2L == 0L
+assert 0L ** 1L == 0L
+assert 0L ** 0L == 1L
+assert 1L ** 0L == 1L
+assert -1L ** 0L == 1L
+assert 1L ** 1L == 1L
+assert 2L ** 1L == 2L
+assert 300L ** 1L == 300L
+assert -1L ** 1L == -1L
+assert -2L ** 1L == -2L
+assert -300L ** 1L == -300L
+assert 0L ** 1L == 0L
+assert 1L ** 0L == 1L
+assert 0L ** 0L == 1L
+assert 1L ** 5L == 1L
+assert 5L ** 5L == 3125L
+assert -5L ** 5L == -3125L
+assert 5L ** 6L == 15625L
+assert -5L ** 6L == 15625L
+assert 1L ** 1L == 1L
+assert 2L ** 1L == 2L
+assert 300L ** 1L == 300L
+assert -1L ** 1L == -1L
+assert -2L ** 1L == -2L
+assert -300L ** 1L == -300L

stdlib/int64.gr

@@ -505,3 +505,30 @@ provide let popcnt = (value: Int64) => {
   let ptr = newInt64(WasmI64.popcnt(nv))
   WasmI32.toGrain(ptr): Int64
 }
+
+// Exponentiation by squaring https://en.wikipedia.org/wiki/Exponentiation_by_squaring special path for int^int
+let rec expBySquaring = (y, x, n) => {
+  if (n == 0L) {
+    1L
+  } else if (n == 1L) {
+    x * y
+  } else if (n % 2L == 0L) {
+    expBySquaring(y, x * x, n / 2L)
+  } else {
+    expBySquaring(x * y, x * x, (n - 1L) / 2L)
+  }
+}
+
+/**
+ * Computes the exponentiation of the given base and power.
+ *
+ * @param base: The base number
+ * @param power: The exponent number
+ * @returns The base raised to the given power
+ *
+ * @since v0.6.0
+ */
+provide let (**) = (base, power) => {
+  if (power < 0L) return expBySquaring(1L, 1L / base, power * -1L)
+  else return expBySquaring(1L, base, power)
+}

stdlib/int64.md

@@ -880,3 +880,29 @@ Returns:
 |----|-----------|
 |`Int64`|The amount of 1-bits in its operand|
 
+### Int64.**(\*\*)**
+
+<details disabled>
+<summary tabindex="-1">Added in <code>next</code></summary>
+No other changes yet.
+</details>
+
+```grain
+(**) : (base: Int64, power: Int64) => Int64
+```
+
+Computes the exponentiation of the given base and power.
+
+Parameters:
+
+|param|type|description|
+|-----|----|-----------|
+|`base`|`Int64`|The base number|
+|`power`|`Int64`|The exponent number|
+
+Returns:
+
+|type|description|
+|----|-----------|
+|`Int64`|The base raised to the given power|
+