init commit

shared/utils/src/optional.ts

@@ -0,0 +1,22 @@
+export type Optional<T> = T | None;
+export type None = null | undefined;
+
+/**
+ * Determine if an optional value is present.
+ *
+ * @param optional value
+ * @return true if present, false otherwise
+ */
+export function isSome<T>(optional: Optional<T>): optional is T {
+    return optional !== null && optional !== undefined;
+}
+
+/**
+ * Determine if an optional value is not present.
+ *
+ * @param optional value
+ * @return true if not present, false otherwise
+ */
+export function isNone<T>(optional: Optional<T>): optional is None {
+    return optional === null || optional === undefined;
+}