A database to cache workflow result and execution traces
It is implemented as a directory in the file system.
init path creates a database located at path path, which can
be absolute or relative. If the path already exists, its contents
is inspected to see if it looks like a bistro database; if not, a
fresh database is created on the filesystem.
Returns an error message if path is occupied with something else
than a bistro database.
val tmp_dir : t ‑> stringval cache_dir : t ‑> stringval stdout_dir : t ‑> stringval stderr_dir : t ‑> stringval build_dir : t ‑> stringval tmp : t ‑> string ‑> stringval cache : t ‑> string ‑> stringval stdout : t ‑> string ‑> stringval stderr : t ‑> string ‑> stringval build : t ‑> string ‑> stringval workflow_path : t ‑> _ Bistro.Workflow.t ‑> string