feat: Add isSomeAnd and isNoneOr (#265)

src/option.test.ts

@@ -147,6 +147,24 @@ Deno.test("xor", () => {
     assertEquals(Option.xor(Option.some(100))(Option.some(2)), Option.none());
 });
 
+Deno.test("isSomeAnd", () => {
+    assertEquals(Option.isSomeAnd((x: number) => x >= 2)(Option.some(2)), true);
+    assertEquals(
+        Option.isSomeAnd((x: number) => x >= 2)(Option.some(1.9)),
+        false,
+    );
+    assertEquals(Option.isSomeAnd((x: number) => x >= 2)(Option.none()), false);
+});
+
+Deno.test("isNoneOr", () => {
+    assertEquals(Option.isNoneOr((x: number) => x >= 2)(Option.some(2)), true);
+    assertEquals(
+        Option.isNoneOr((x: number) => x >= 2)(Option.some(1.9)),
+        false,
+    );
+    assertEquals(Option.isNoneOr((x: number) => x >= 2)(Option.none()), true);
+});
+
 Deno.test("filter", () => {
     const isEven = Option.filter((x: number) => x % 2 === 0);
     assertEquals(isEven(Option.none()), Option.none());

src/option.ts

@@ -405,6 +405,30 @@ export const xor = <T>(optB: Option<T>) => (optA: Option<T>): Option<T> => {
     return none();
 };
 
+/**
+ * Checks an {@link Option.Option | `Option`} is a `Some` and satisfies the predicate `pred`.
+ *
+ * It is equivalent to `!isNoneOr((item) => !pred(item))`.
+ *
+ * @param pred - The predicate to check.
+ * @returns Whether the condition is satisfied.
+ */
+export const isSomeAnd =
+    <T>(pred: (item: T) => boolean) => (opt: Option<T>): boolean =>
+        isSome(opt) && pred(opt[1]);
+
+/**
+ * Checks an {@link Option.Option | `Option`} is a `None` or satisfies the predicated `pred`.
+ *
+ * It is equivalent to `!isSomeAnd((item) => !pred(item))`.
+ *
+ * @param pred - The predicate to check.
+ * @returns Whether the condition is satisfied.
+ */
+export const isNoneOr =
+    <T>(pred: (item: T) => boolean) => (opt: Option<T>): boolean =>
+        isNone(opt) || pred(opt[1]);
+
 /**
  * Returns `Some` only if `opt` is a `Some` and its value satisfies `predicate`, otherwise returns `None`.
  *