fs

POSIX file I/O on integer fds. open is read-only; create is write/trunc. read/write/close use the fd; pread(fd, off, n) reads at an offset. mkdir creates one directory. Every call returns result[_, str], except fstat(fd), which is [kind, size, mtime_sec, mtime_nsec] of an open file (kind 0 a regular file, 1 a directory, 2 anything else; [] for a closed fd). realpath(path) resolves ., .. and every symlink to an absolute path: what a file server compares with its root, so a link cannot lead out of it. These calls block the worker — use them for config and small files, not the accept loop. To read standard input use io instead: fs.read(0, n) works, but waits by blocking a whole worker thread, and a program waiting on a person at a keyboard would stall every other task with it.

import "fs";

let cr = fs.create("/tmp/note");
guard let fd = cr else { exit(1); }
fs.write(fd, b"hi");
fs.close(fd);

let or = fs.open("/tmp/note");
guard let in_fd = or else { exit(1); }
let rr = fs.read(in_fd, 16);
guard let data = rr else { exit(1); }
fs.close(in_fd);

API#