src/walk/disk.bend
bolt@1.12.0.0 · 76 lines · 0 definitions
1# walk/disk: an effect (CPU event loop only): the names directly in a
2# directory, whether a path is a directory, and the working directory
3# relative paths are named from. A name that is itself a directory ends in
4# "/"; "." and ".." are never in the list, and a directory that cannot be
5# opened lists as empty. Order is the file system's; the lint planner
6# (src/lint/plan.bend) sorts what it keeps.
7#
8# It is the real file system, through a foreign effect (dir.c, dir.js) that
9# lists one directory: its names, one a line, a directory's name ending in
10# "/"; one (cwd.c, cwd.js) that names the working directory; and Base's
11# File, which tells a directory from a file.
12import Base
13
14# every name directly in the directory, one a line
15def walkdir.entries(dir: String) -> IO(String):
16 import "./dir.c"
17 import "./dir.js"
18
19# the named lines: the text ends in a newline, so the last line is empty
20def named(ls: List<&2, String>) -> List<&2, String>:
21 match ls:
22 case Nil{}:
23 Nil{}
24 case Con{+l, t}:
25 +more = named(t)
26 Bool.pick(List<&2, String>, String.is_empty(l), more, l <> more)
27
28# a directory's entries, a directory marked by a `/`
29def entries(dir: String) -> IO(List<&2, String>): # noqa: L001 disk effect
30 do IO<List<&2, String>>:
31 text : String <- walkdir.entries(dir)
32 return named(String.lines(text))
33
34# whether a first read failed as a directory's does (EISDIR, 21, in C and
35# in node alike)
36def is_dir.code(rr: Result<&1, &1, U32 & String, List<&2, U32>>) -> Bool:
37 match rr:
38 case Fail{e}:
39 (code, _msg) = e
40 U32.is_eq(code, 21)
41 case Done{_bytes}:
42 False{}
43
44# the file closed, and what its first read said
45def is_dir.got(got: File & Result<&1, &1, U32 & String, List<&2, U32>>) -> IO(Bool):
46 (file, rr) = got
47 do IO<Bool>:
48 File.close(file)
49 return is_dir.code(rr)
50
51# a path that opened: read one byte and see; one that did not is no directory
52def is_dir.opened(rr: Result<&1, &1, U32 & String, File>) -> IO(Bool):
53 match rr:
54 case Fail{_e}:
55 IO.pure(Bool, False{})
56 case Done{file}:
57 do IO<Bool>:
58 got : File & Result<&1, &1, U32 & String, List<&2, U32>> <- File.read_bytes(file, 1)
59 is_dir.got(got)
60
61# whether a path is a directory: it opens, and reading it fails as a
62# directory's read does. Base's File has no stat, and a directory opens for
63# reading on both lanes.
64def is_dir(path: String) -> IO(Bool): # noqa: L001 disk effect
65 do IO<Bool>:
66 r : Result<&1, &1, U32 & String, File> <- File.open(path, "r")
67 is_dir.opened(r)
68
69# the working directory, from the root; "" when it cannot be named
70def walkdir.cwd() -> IO(String):
71 import "./cwd.c"
72 import "./cwd.js"
73
74# the working directory, from the root ("" when it cannot be named)
75def cwd() -> IO(String): # noqa: L001 disk effect
76 walkdir.cwd()