Added initial Result implementation

src/core/result.ts

@@ -0,0 +1,43 @@
+export type Ok<T> = [null, T];
+export type Error<E> = [E, null];
+export type Result<T, E> = Ok<T> | Error<E>;
+
+/**
+ * A type predicate for the Error type
+ * ```ts
+ * if (isError(result)) {
+ *   // can safely call `getError(result)` here
+ * } else {
+ *   // can safely call `getValue(result)` here
+ * }
+ * ```
+ */
+export function isError<E>(input: Result<unknown, E>): input is Error<E> {
+    return input[1] === null;
+}
+
+export function getValue<T>(input: Ok<T>): T {
+    return input[1];
+}
+
+export function getError<E>(input: Error<E>): E {
+    return input[0];
+}
+
+/**
+ * Returns the value of a result, or throws the error if present.
+ */
+export function unsafeUnwrap<T>(input: Result<T, unknown>): T {
+    if (isError(input)) {
+        throw getError(input);
+    }
+    return getValue(input);
+}
+
+export function ok<T>(value: T): Ok<T> {
+    return [null, value];
+}
+
+export function error<E>(error: E): Error<E> {
+    return [error, null];
+}