Pop a value from the current state and return it as a monadic value. The state is assumed to be a list.

Restore the file set ("nar bundle") read from PORT to the store. The format of the data on PORT must be as created by 'export-paths'---i.e., a series of Nar-formatted archives with interspersed meta-data joining them together, possibly with a digital signature at the end. Log progress to LOG-PORT. Return the list of files restored.

When LOCK? is #f, assume locks for the files to be restored are already held. This is the case when the daemon calls a build hook.

Note that this procedure accesses the store directly, so it's only meant to be used by the daemon's build hooks since they cannot call back to the daemon while the locks are held.

Return the sorted list of "preferred" nar URIs from NARINFO (preferred comes first) where each entry is a tuple containing: the URI, its compression method (a string), and the compressed file size.

When FAST-DECOMPRESSION? is true, prefer substitutes with faster decompression (typically zstd) rather than substitutes with a higher compression ratio (typically lzip).