export type TaggedStruct<Tag extends SchemaAST.LiteralValue, Fields extends Struct.Fields> = Struct<
  Simplify<{ readonly _tag: tag<Tag> } & Fields>
>

/**
 * Creates a struct schema with an automatically populated `_tag` field.
 *
 * **When to use**
 *
 * Use to define a tagged union case from a literal tag and a set of fields.
 *
 * **Details**
 *
 * When using the `make` method, the `_tag` field is optional and will be
 * added automatically. However, when decoding or encoding, the `_tag` field
 * must be present in the input.
 *
 * **Example** (Defining a tagged struct shorthand)
 *
 * ```ts
 * import { Schema } from "effect"
 *
 * // Defines a struct with a fixed `_tag` field
 * const tagged = Schema.TaggedStruct("A", {
 *   a: Schema.String
 * })
 *
 * // This is the same as writing:
 * const equivalent = Schema.Struct({
 *   _tag: Schema.tag("A"),
 *   a: Schema.String
 * })
 * ```
 *
 * **Example** (Accessing the literal value of the tag)
 *
 * ```ts
 * import { Schema } from "effect"
 *
 * const tagged = Schema.TaggedStruct("A", {
 *   a: Schema.String
 * })
 *
 * // literal: "A"
 * const literal = tagged.fields._tag.schema.literal
 * ```
 *
 * @category constructors
 * @since 3.10.0
 */
export function TaggedStruct<const Tag extends SchemaAST.LiteralValue, const Fields extends Struct.Fields>(
  value: Tag,
  fields: Fields
): TaggedStruct<Tag, Fields> {
  return Struct({ _tag: tag(value), ...fields })
}