feat: Optional type is no longer exported

src/json/serializr.ts

@@ -3,8 +3,8 @@ import type { AdditionalPropArgs, ModelSchema, PropDeserializer, PropSchema, Pro
 
 import { Err, Ok } from '../factory';
 import { RustlikeResult } from '../result';
-import type { Optional, Result } from '../types';
-import type { ResultType } from '../types.internal';
+import type { Result } from '../types';
+import type { Optional, ResultType } from '../types.internal';
 
 import type { ResultJson } from './types';
 

src/result.ts

@@ -1,5 +1,5 @@
-import type { Optional, Result } from './types';
-import type { ResultType } from './types.internal';
+import type { Result } from './types';
+import type { Optional, ResultType } from './types.internal';
 
 /**
  * The default implementation of interface `Result`.

src/types.internal.ts

@@ -1 +1,16 @@
 export type ResultType = 'ok' | 'err';
+
+/**
+ * JavaScript ECMAScript 2020 contains two new proposals that can help us deal with undefined/null more easily:
+ * - https://github.com/tc39/proposal-optional-chaining
+ * - https://github.com/tc39/proposal-nullish-coalescing
+ *
+ * We don't need Rust-like Option anymore in most cases unless we want functional programming.
+ *
+ * This type doesn't use the name `Option`,
+ * by giving it a different name we can easily know that this is not Rust-like Option.
+ *
+ * This type is not exported since there's no convention for using `Optional` type in TypeScript world.
+ * People just simply write `T | undefined`.
+ */
+export type Optional<T> = T | undefined;

src/types.ts

@@ -1,14 +1,4 @@
-/**
- * JavaScript ECMAScript 2020 contains two new proposals that can help us deal with undefined/null more easily:
- * - https://github.com/tc39/proposal-optional-chaining
- * - https://github.com/tc39/proposal-nullish-coalescing
- *
- * We don't need Rust-like Option anymore in most cases unless we want functional programming.
- *
- * This type doesn't use the name `Option`,
- * by giving it a different name we can easily know that this is not Rust-like Option.
- */
-export type Optional<T> = T | undefined;
+import type { Optional } from './types.internal';
 
 /**
  * The interface of `Result` that defines the methods that `Result` should support.