std/storage

Bytes at a reference, wherever the scheme of the reference reaches (docs/design/URI.md section 11). Storage is the capability - read, exists, list, write, delete - and a driver is a shared type that has it for its schemes: FileStorage for file: over std/fs, and MemoryStorage for memory:, the double every test of a program that stores things needs. S3, WebDAV and the rest are packages of their own, whose drivers have the same trait.

The program names its drivers, and nothing registers itself. Storage.registry is one storage over several drivers, chosen by the scheme of each reference it is handed, and a scheme it was not given is a failure that lists the ones it was:

use Storage, StorageFailure, FileStorage, MemoryStorage from "std/storage"

fn stored(): Task<Result<String, StorageFailure>> {
  var storage = Storage.registry([FileStorage(), MemoryStorage()])
  storage.writeText("memory:/notes/first", "hello").await()?
  storage.readText("memory:/notes/first").await()
}

A reference is a Uri, so a relative one has no scheme to choose a driver by and is resolved against a base first (reference.resolved(against: base)). Every failure carries the reference as show() wrote it, so a password in a reference never reaches a log through a failure.