val copy_file :
B0_memo.t ->src_root:B0_std.Fpath.t ->dst_root:B0_std.Fpath.t ->B0_std.Fpath.t ->
unit
copy m ~src_root ~dst_root src copies src to destination root_path ~src_root ~dst_root src.
val ensure_exec_build :
B0_memo.t ->srcs:B0_file_exts.map ->need_ext:B0_std.Fpath.ext ->unit B0_std.Fut.t
ensure_exe_build m ~srcs ~need_ext k continues iff there's at least a file in srcs that has exention need_ext and fails with a message that no executable can be built otherwise.
val run :
with_log:B0_std.Fpath.t option->B0_memo.t ->(unit ->'aB0_std.Fut.t)->('a, unit)Stdlib.result