Add Array.unsafe_get for compatibility

Author: cknitt

runtime/array.res

@@ -3,6 +3,8 @@
 external getUnsafe: (array<'a>, int) => 'a = "%array_unsafe_get"
 external setUnsafe: (array<'a>, int, 'a) => unit = "%array_unsafe_set"
 
+external unsafe_get: (array<'a>, int) => 'a = "%array_unsafe_get"
+
 @val external fromIterator: Iterator.t<'a> => array<'a> = "Array.from"
 @val external fromArrayLike: Js.Array2.array_like<'a> => array<'a> = "Array.from"
 @val

runtime/array.resi

@@ -862,6 +862,25 @@ for index in 0 to array->Array.length - 1 {
 */
 external getUnsafe: (array<'a>, int) => 'a = "%array_unsafe_get"
 
+/**
+`unsafe_get(array, index)` returns the element at `index` of `array`.
+
+This is _unsafe_, meaning it will return `undefined` value if `index` does not exist in `array`.
+
+Use `Array.unsafe_get` only when you are sure the `index` exists (i.e. when using for-loop).
+
+## Examples
+```rescript
+let array = [1, 2, 3]
+for index in 0 to array->Array.length - 1 {
+  let value = array->Array.unsafe_get(index)
+  Console.log(value)
+}
+```
+*/
+@deprecated("Use getUnsafe instead. This will be removed in v13")
+external unsafe_get: (array<'a>, int) => 'a = "%array_unsafe_get"
+
 /**
 `setUnsafe(array, index, item)` sets the provided `item` at `index` of `array`.