Api improvements

src/index.ts

@@ -52,3 +52,4 @@ export * from './constants';
 export * from './schema';
 export * from './type';
 export * from './system';
+export * from './value';

src/random/generators.ts

@@ -65,10 +65,14 @@ export const num = (type: NumberType): number => {
   let min = Number.MIN_SAFE_INTEGER;
   let max = Number.MAX_SAFE_INTEGER;
   const schema = type.getSchema();
-  if (schema.gt !== undefined) min = schema.gt;
-  if (schema.gte !== undefined) min = schema.gte + 0.000000000000001;
-  if (schema.lt !== undefined) max = schema.lt;
-  if (schema.lte !== undefined) max = schema.lte - 0.000000000000001;
+  const {lt, lte, gt, gte} = schema;
+  if (gt !== undefined) min = gt;
+  if (gte !== undefined)
+    if (gte === lte) return gte;
+    else min = gte + 0.000000000000001;
+  if (lt !== undefined) max = lt;
+  if (lte !== undefined) max = lte - 0.000000000000001;
+  if (min >= max) return max;
   if (schema.format) {
     switch (schema.format) {
       case 'i8':

src/schema/SchemaBuilder.ts

@@ -19,6 +19,7 @@ import type {
   FunctionSchema,
   FunctionStreamingSchema,
   TType,
+  Narrow,
 } from '.';
 
 export class SchemaBuilder {
@@ -127,7 +128,7 @@ export class SchemaBuilder {
    * ```
    */
   public Const<V>(
-    value: V,
+    value: Narrow<V>,
     options?: Optional<ConstSchema<V>>,
   ): ConstSchema<
     string extends V ? never : number extends V ? never : boolean extends V ? never : any[] extends V ? never : V

src/schema/__tests__/SchemaBuilder.spec.ts

@@ -1,4 +1,4 @@
-import {s} from '..';
+import {type ConstSchema, s} from '..';
 
 describe('string', () => {
   test('can create a string type', () => {
@@ -79,3 +79,14 @@ describe('or', () => {
     });
   });
 });
+
+describe('const', () => {
+  test('can create an "const" type', () => {
+    const type = s.Const('Hello');
+    const type2: ConstSchema<'Hello'> = type;
+    expect(type2).toEqual({
+      kind: 'const',
+      value: 'Hello',
+    });
+  });
+});

src/schema/index.ts

@@ -1,9 +1,14 @@
+import type {TypeOf} from './schema';
 import {SchemaBuilder} from './SchemaBuilder';
 
 export * from './common';
 export * from './schema';
 
 /**
- * JSON Type AST builder.
+ * JSON Type default AST builder.
  */
 export const s = new SchemaBuilder();
+
+export namespace s {
+  export type infer<T> = TypeOf<T>;
+}

src/schema/schema.ts

@@ -16,6 +16,13 @@ export interface TType<Value = unknown> extends Display, Partial<Identifiable> {
    */
   meta?: Record<string, unknown>;
 
+  /**
+   * Default value for this type. This may be used when the value is not provided
+   * during validation or serialization. The default value should match the
+   * type of this schema node.
+   */
+  default?: Value;
+
   /**
    * List of example usages of this type.
    */
@@ -52,6 +59,17 @@ export interface WithValidator {
 
 /**
  * Represents something of which type is not known.
+ *
+ * Example:
+ *
+ * ```json
+ * {
+ *   "kind": "any",
+ *   "metadata": {
+ *     "description": "Any type"
+ *   }
+ * }
+ * ```
  */
 export interface AnySchema extends TType<unknown>, WithValidator {
   kind: 'any';
@@ -65,13 +83,35 @@ export interface AnySchema extends TType<unknown>, WithValidator {
 
 /**
  * Represents a JSON boolean.
+ *
+ * Example:
+ *
+ * ```json
+ * {
+ *   "kind": "bool",
+ *   "meta": {
+ *     "description": "A boolean value"
+ *   }
+ * }
+ * ```
  */
 export interface BooleanSchema extends TType<boolean>, WithValidator {
   kind: 'bool';
 }
 
 /**
  * Represents a JSON number.
+ *
+ * Example:
+ *
+ * ```json
+ * {
+ *   "kind": "num",
+ *   "format": "i32",
+ *   "gte": 0,
+ *   "lte": 100
+ * }
+ * ```
  */
 export interface NumberSchema extends TType<number>, WithValidator {
   kind: 'num';
@@ -112,6 +152,17 @@ export interface NumberSchema extends TType<number>, WithValidator {
 
 /**
  * Represents a JSON string.
+ *
+ * Example:
+ *
+ * ```json
+ * {
+ *   "kind": "str",
+ *   "format": "utf8",
+ *   "min": 1,
+ *   "max": 255
+ * }
+ * ```
  */
 export interface StringSchema extends TType<string>, WithValidator {
   kind: 'str';
@@ -150,6 +201,20 @@ export interface StringSchema extends TType<string>, WithValidator {
 
 /**
  * Represents a binary type.
+ *
+ * Example:
+ *
+ * ```json
+ * {
+ *   "kind": "bin",
+ *   "type": {
+ *     "kind": "str"
+ *   },
+ *   "format": "json",
+ *   "min": 10,
+ *   "max": 1024
+ * }
+ * ```
  */
 export interface BinarySchema<T extends TType = any> extends TType, WithValidator {
   kind: 'bin';
@@ -169,6 +234,19 @@ export interface BinarySchema<T extends TType = any> extends TType, WithValidato
 
 /**
  * Represents a JSON array.
+ *
+ * Example:
+ *
+ * ```json
+ * {
+ *   "kind": "arr",
+ *   "type": {
+ *     "kind": "num"
+ *   },
+ *   "min": 1,
+ *   "max": 10
+ * }
+ * ```
  */
 export interface ArraySchema<T extends TType = any> extends TType<Array<unknown>>, WithValidator {
   kind: 'arr';
@@ -182,6 +260,13 @@ export interface ArraySchema<T extends TType = any> extends TType<Array<unknown>
 
 /**
  * Represents a constant value.
+ * Example:
+ * ```json
+ * {
+ *   "kind": "const",
+ *   "value": 42
+ * }
+ * ```
  */
 export interface ConstSchema<V = any> extends TType, WithValidator {
   /** @todo Rename to "con". */
@@ -202,6 +287,32 @@ export interface TupleSchema<T extends TType[] = any> extends TType, WithValidat
 /**
  * Represents a JSON object type, the "object" type excluding "null" in JavaScript,
  * the "object" type in JSON Schema, and the "obj" type in MessagePack.
+ * Example:
+ * ```json
+ * {
+ *   "kind": "obj",
+ *   "fields": [
+ *     {
+ *       "kind": "field",
+ *       "key": "name",
+ *       "type": {
+ *         "kind": "str"
+ *       },
+ *       "optional": false
+ *     },
+ *     {
+ *       "kind": "field",
+ *       "key": "age",
+ *       "type": {
+ *         "kind": "num",
+ *         "gte": 0
+ *       },
+ *       "optional": true
+ *     }
+ *   ],
+ *   "unknownFields": false
+ * }
+ * ```
  */
 export interface ObjectSchema<
   Fields extends ObjectFieldSchema<string, TType>[] | readonly ObjectFieldSchema<string, TType>[] = any,
@@ -246,8 +357,14 @@ export interface ObjectFieldSchema<K extends string = string, V extends TType =
   kind: 'field';
   /** Key name of the field. */
   key: K;
-  /** One or more "one-of" types of the field. */
+
+  /**
+   * One or more "one-of" types of the field.
+   *
+   * @todo Rename to `val`.
+   */
   type: V;
+
   optional?: boolean;
 }
 
@@ -262,7 +379,11 @@ export interface ObjectOptionalFieldSchema<K extends string = string, V extends
  */
 export interface MapSchema<T extends TType = any> extends TType<Record<string, unknown>>, WithValidator {
   kind: 'map';
-  /** Type of all values in the map. */
+  /**
+   * Type of all values in the map.
+   *
+   * @todo Rename to `val`. And add `key` field for the key type. Make `key` default to `str`.
+   */
   type: T;
 }
 
@@ -299,6 +420,7 @@ export interface FunctionSchema<Req extends TType = TType, Res extends TType = T
 export type FunctionStreamingValue<Req, Res, Ctx = unknown> = (req: Observable<Req>, ctx?: Ctx) => Observable<Res>;
 
 export interface FunctionStreamingSchema<Req extends TType = TType, Res extends TType = TType> extends TType {
+  /** @todo Rename to `fn`. Make it a property on the schema instead. */
   kind: 'fn$';
   req: Req;
   res: Res;
@@ -396,3 +518,8 @@ export type OptionalProps<T extends object> = Exclude<
 
 export type Optional<T extends object> = Pick<T, OptionalProps<T>>;
 export type Required<T extends object> = Omit<T, OptionalProps<T>>;
+
+export type Narrow<T> =
+  | (T extends infer U ? U : never)
+  | Extract<T, number | string | boolean | bigint | symbol | null | undefined | []>
+  | ([T] extends [[]] ? [] : {[K in keyof T]: Narrow<T[K]>});

src/system/types.ts

@@ -23,3 +23,5 @@ export type ResolveType<T> = T extends TypeAlias<any, infer T>
     : T extends Schema
       ? TypeOf<T>
       : never;
+
+export type infer<T> = ResolveType<T>;