B0_dirval build_dir : b0_dir:B0_std.Fpath.t -> variant:string -> B0_std.Fpath.tval store_dir : build_dir:B0_std.Fpath.t -> B0_std.Fpath.tval unit_build_dir : build_dir:B0_std.Fpath.t -> name:string -> B0_std.Fpath.tval scratch_dir : b0_dir:B0_std.Fpath.t -> B0_std.Fpath.t