src/walk/disk.bend source

src/walk/disk.bend on the hub · documented module

# walk/disk: an effect (CPU event loop only): the names directly in a# directory, whether a path is a directory, and the working directory# relative paths are named from. A name that is itself a directory ends in# "/"; "." and ".." are never in the list, and a directory that cannot be# opened lists as empty. Order is the file system's; the lint planner# (src/lint/plan.bend) sorts what it keeps.## It is the real file system, through a foreign effect (dir.c, dir.js) that# lists one directory: its names, one a line, a directory's name ending in# "/"; one (cwd.c, cwd.js) that names the working directory; and Base's# File, which tells a directory from a file.import Base# every name directly in the directory, one a linedef walkdir.entries(dir: String) -> IO(String):  import "./dir.c"  import "./dir.js"# the named lines: the text ends in a newline, so the last line is emptydef named(ls: List<&2, String>) -> List<&2, String>:  match ls:    case Nil{}:      Nil{}    case Con{+l, t}:      +more = named(t)      Bool.pick(List<&2, String>, String.is_empty(l), more, l <> more)# a directory's entries, a directory marked by a `/`def entries(dir: String) -> IO(List<&2, String>):  # noqa: L001 disk effect  do IO<List<&2, String>>:    text : String <- walkdir.entries(dir)    return named(String.lines(text))# whether a first read failed as a directory's does (EISDIR, 21, in C and# in node alike)def is_dir.code(rr: Result<&1, &1, U32 & String, List<&2, U32>>) -> Bool:  match rr:    case Fail{e}:      (code, _msg) = e      U32.is_eq(code, 21)    case Done{_bytes}:      False{}# the file closed, and what its first read saiddef is_dir.got(got: File & Result<&1, &1, U32 & String, List<&2, U32>>) -> IO(Bool):  (file, rr) = got  do IO<Bool>:    File.close(file)    return is_dir.code(rr)# a path that opened: read one byte and see; one that did not is no directorydef is_dir.opened(rr: Result<&1, &1, U32 & String, File>) -> IO(Bool):  match rr:    case Fail{_e}:      IO.pure(Bool, False{})    case Done{file}:      do IO<Bool>:        got : File & Result<&1, &1, U32 & String, List<&2, U32>> <- File.read_bytes(file, 1)        is_dir.got(got)# whether a path is a directory: it opens, and reading it fails as a# directory's read does. Base's File has no stat, and a directory opens for# reading on both lanes.def is_dir(path: String) -> IO(Bool):  # noqa: L001 disk effect  do IO<Bool>:    r : Result<&1, &1, U32 & String, File> <- File.open(path, "r")    is_dir.opened(r)# the working directory, from the root; "" when it cannot be nameddef walkdir.cwd() -> IO(String):  import "./cwd.c"  import "./cwd.js"# the working directory, from the root ("" when it cannot be named)def cwd() -> IO(String):  # noqa: L001 disk effect  walkdir.cwd()