Return a fixed-output derivation that fetches REF, a <bzr-reference> object. The output is expected to have recursive hash HASH of type HASH-ALGO (a symbol). Use NAME as the file name, or a generic name if #f.

Like 'delete-file', but does not raise an error when FILE does not exist.

Return #t if DATE is obsolete compared to NOW + TTL seconds.

Given ENTRIES, a list of file names, remove those whose expiration time, as returned by ENTRY-EXPIRATION, has passed. Use DELETE-ENTRY to delete them.

Return a procedure that, when passed a file, returns its "expiration time" computed as its timestamp + TTL seconds. Call TIMESTAMP to obtain the relevant timestamp from the result of 'stat'.

Remove expired narinfo entries from the cache if deemed necessary. Call CACHE-ENTRIES with CACHE to retrieve the list of cache entries.

ENTRY-EXPIRATION must be a procedure that, when passed an entry, returns the expiration time of that entry in seconds since the Epoch. DELETE-ENTRY is a procedure that removes the entry passed as an argument. Finally, CLEANUP-PERIOD denotes the minimum time between two cache cleanups.

Return a new channel introduction: COMMIT is the introductory where authentication starts, and SIGNER is the OpenPGP fingerprint (a bytevector) of the signer of that commit.

Return the list of channels that are declared as dependencies for the given channel INSTANCE.

Raise an error if RELATION is not 'ancestor, meaning that START is not an ancestor of COMMIT, unless CHANNEL specifies a commit.

This procedure implements a channel update policy meant to be used as a #:validate-pull argument.

Return a channel instance for CHECKOUT, which is assumed to be a checkout of COMMIT at URL. Use NAME as the channel name.