Effect.ts + SvelteKit remote functions

effect-remote-functions.ts

import type {
	RemoteCommand,
	RemoteForm,
	RemoteFormInput,
	RemoteQueryFunction
} from "@sveltejs/kit";
import { command, form, query } from "$app/server";
import { Effect, Schema } from "effect";

/**
 * Creates a remote query defined with `Effect`. Shares the same behaviour as
 * SvelteKit's `query`.
 *
 * @param schema The `Schema` to validate arguments against.
 * @param handler The `Effect` to run when this function is ran. When `E` is `never`, then the return value will be non-nullish, otherwise the result can be `undefined`.
 * @template A success value for the given `Effect`.
 * @template E possible error for the given `Effect`.
 * @template QueryReturn `A` when `E == never`, otherwise `A | undefined`.
 * @see query
 */
export const effectfulQuery = <
	A,
	E,
	ASchema,
	ISchema,
	QueryReturn = E extends never ? A : A | undefined
>(
	schema: Schema.Schema<ASchema, ISchema, never>,
	handler: (args: ASchema) => Effect.Effect<A, E, never>
): RemoteQueryFunction<ISchema, QueryReturn> =>
	query(Schema.standardSchemaV1(schema), async args =>
		Effect.runPromise(
			Effect.gen(function* () {
				const result = handler(args);

				if (yield* Effect.isSuccess(result)) {
					return yield* result;
				} else {
					yield* Effect.tapError(result, error =>
						Effect.logError(`An error occurred in remote query function: ${error}`)
					);

					return undefined;
				}
			})
		)
	) as RemoteQueryFunction<ISchema, QueryReturn>;

/**
 * Creates a remote batch query defined with `Effect`. Shares the same
 * behaviour as SvelteKit's `query.batch`.
 *
 * @param schema The `Schema` to validate arguments against.
 * @param handler The `Effect` to run when this function is ran. When `E` is `never`, then the return value will be non-nullish, otherwise the result can be `undefined`.
 * @template A success value for the given `Effect`.
 * @template E possible error for the given `Effect`.
 * @template BatchQueryReturn `A` when `E == never`, otherwise `A | undefined`.
 * @see query.batch
 */
export const effectfulBatchQuery = <
	A,
	E,
	ASchema,
	ISchema,
	BatchQueryReturn = E extends never ? A : A | undefined
>(
	schema: Schema.Schema<ASchema, ISchema, never>,
	handler: (
		args: ASchema[]
	) => Effect.Effect<(args: ASchema, index?: number) => Effect.Effect<BatchQueryReturn, E, never>>
): RemoteQueryFunction<ISchema, BatchQueryReturn> =>
	query.batch(Schema.standardSchemaV1(schema), async args => {
		const lookup = handler(args);

		return (arg, index) =>
			Effect.runSync(
				Effect.gen(function* () {
					const fn = yield* lookup;
					const result = fn(arg, index);

					if (yield* Effect.isSuccess(result)) {
						return yield* result;
					} else {
						yield* Effect.tapError(result, error =>
							Effect.logError(
								`An error occurred in remote query batch function [index: ${index}, arg: ${arg}]: ${error}`
							)
						);

						return undefined;
					}
				})
			);
	}) as RemoteQueryFunction<ISchema, BatchQueryReturn>;

/* eslint-disable @typescript-eslint/no-explicit-any */
/**
 * Creates a remote form function defined with `Effect`. Shares the same
 * behaviour as SvelteKit's `form`.
 *
 * @param schema The `Schema` to validate arguments and fields against.
 * @param handler The `Effect` to run when this function is ran. When `E` is `never`, then the return value will be non-nullish, otherwise the result can be `undefined`.
 * @template A success value for the given `Effect`.
 * @template E possible error for the given `Effect`.
 * @template FormReturn `A` when `E == never`, otherwise `A | undefined`.
 * @see form
 */
export const effectfulForm = <
	A,
	E,
	ASchema extends Record<string, any>,
	ISchema extends RemoteFormInput,
	FormReturn = E extends never ? A : A | undefined
>(
	schema: Schema.Schema<ASchema, ISchema, never>,
	handler: (args: ASchema) => Effect.Effect<A, E, never>
): RemoteForm<ISchema, FormReturn> =>
	form(Schema.standardSchemaV1(schema), async args =>
		Effect.runPromise(
			Effect.gen(function* () {
				const result = handler(args);

				if (yield* Effect.isSuccess(result)) {
					return yield* result;
				} else {
					yield* Effect.tapError(result, error =>
						Effect.logError(`An error occurred in remote form function: ${error}`)
					);

					return undefined;
				}
			})
		)
	) as RemoteForm<ISchema, FormReturn>;
/* eslint-enable @typescript-eslint/no-explicit-any */

/**
 * Creates a remote command function defined with `Effect`. Shares the same
 * behaviour as SvelteKit's `command`.
 *
 * @param schema The `Schema` to validate arguments and fields against.
 * @param handler The `Effect` to run when this function is ran. When `E` is `never`, then the return value will be non-nullish, otherwise the result can be `undefined`.
 * @template A success value for the given `Effect`.
 * @template E possible error for the given `Effect`.
 * @template CommandReturn `A` when `E == never`, otherwise `A | undefined`.
 * @see command
 */
export const effectfulCommand = <
	A,
	E,
	ASchema,
	ISchema,
	CommandReturn = E extends never ? A : A | undefined
>(
	schema: Schema.Schema<ASchema, ISchema, never>,
	handler: (args: ASchema) => Effect.Effect<A, E, never>
): RemoteCommand<ISchema, CommandReturn> =>
	command(Schema.standardSchemaV1(schema), async args =>
		Effect.runPromise(
			Effect.gen(function* () {
				const result = handler(args);

				if (yield* Effect.isSuccess(result)) {
					return yield* result;
				} else {
					yield* Effect.tapError(result, error =>
						Effect.logError(`An error occurred in remote command function: ${error}`)
					);

					return undefined;
				}
			})
		)
	) as RemoteCommand<ISchema, CommandReturn>;