#miniio

#Public API

• args_get()
• environ_get()
• get_env_var(), get_env_vars()
• moonbit-community/miniio/io::{Data, Reader, Writer}
• stdin, stdout, stderr
• open, create
• File::close
• File::write_all
• File::write_text
• File::seek
• File::tell
• Reader::{read, read_exactly, read_some, read_all, read_until}
• Writer::{write, write_reader}
• mkdir, remove_file, remove, rmdir
• readdir
• exists, kind, is_dir, is_file
• read_file, write_file, copy_file
• read_text_file, write_text_file
• read_json_file, write_json_file
• Errno, CreateMode, FileKind, Mode, SeekFrom

#Scope

• args_sizes_get, args_get
• environ_sizes_get, environ_get
• fd_read, fd_write, fd_close, fd_readdir, fd_prestat_*, fd_seek, fd_tell
• path_open, path_create_directory, path_unlink_file, path_remove_directory
• preopen discovery and path resolution
• rights, flags, cookies, raw fd types

• async runtime and async I/O
• detailed metadata/stat helpers such as mtime, sizes, permissions, and file descriptor rights
• symlink, rename, link, walk
• raw preview1-shaped public calls

#Common File Patterns

///|
test "copy text between files" {
  let dir = "readme_copy_text"
  @miniio.remove(dir) catch {
    Noent => ()
    Notempty => @miniio.rmdir(dir, recursive=true)
    e => raise e
  }
  @miniio.mkdir(dir)
  defer ignore(try! @miniio.rmdir(dir, recursive=true))

  @miniio.write_text_file(dir + "/input.txt", "hello\n")
  @miniio.copy_file(dir + "/input.txt", dir + "/output.txt")
  inspect(@miniio.read_text_file(dir + "/output.txt"), content="hello\n")
}

///|
test "append log file" {
  let dir = "readme_append_log"
  @miniio.remove(dir) catch {
    Noent => ()
    Notempty => @miniio.rmdir(dir, recursive=true)
    e => raise e
  }
  @miniio.mkdir(dir)
  defer ignore(try! @miniio.rmdir(dir, recursive=true))

  let path = dir + "/tool.log"
  @miniio.write_text_file(path, "start\n")
  @miniio.write_text_file(path, "done\n", append=true)
  inspect(@miniio.read_text_file(path), content="start\ndone\n")
}

///|
test "read and write json" {
  let dir = "readme_json"
  @miniio.remove(dir) catch {
    Noent => ()
    Notempty => @miniio.rmdir(dir, recursive=true)
    e => raise e
  }
  @miniio.mkdir(dir)
  defer ignore(try! @miniio.rmdir(dir, recursive=true))

  let path = dir + "/manifest.json"
  @miniio.write_json_file(path, { "name": "miniio", "portable": true })
  inspect(
    @miniio.read_json_file(path).stringify(),
    content="{\"name\":\"miniio\",\"portable\":true}",
  )
}

///|
test "list and remove directories" {
  let dir = "readme_list_remove"
  @miniio.remove(dir) catch {
    Noent => ()
    Notempty => @miniio.rmdir(dir, recursive=true)
    e => raise e
  }
  @miniio.mkdir(dir)

  @miniio.write_text_file(dir + "/b.txt", "b")
  @miniio.write_text_file(dir + "/a.txt", "a")
  debug_inspect(
    @miniio.readdir(dir, sort=true),
    content="[\"a.txt\", \"b.txt\"]",
  )

  @miniio.rmdir(dir, recursive=true)
  inspect(@miniio.exists(dir), content="false")
}

#WASIp1 Guest Paths

wasmtime run --dir ./data::data _build/wasm/debug/build/<module>/<package>.wasm data/input.txt

#Quick Eval

printf '{"name":"miniio","ok":true}' | moon run -c 'import {
  "moonbit-community/miniio" @miniio,
  "moonbit-community/miniio/io",
  "moonbitlang/core/json" @json,
}

fn main {
  try {
    let input = @miniio.stdin.read_all().text()
    let value = @json.parse(input)
    @miniio.stdout.write_text(value.stringify(indent=2) + "\n")
  } catch {
    e => {
      @miniio.stderr.write_text("jq failed: \{e}\n") catch { _ => () }
      @miniio.exit(1)
    }
  }
}'

#Examples

• example/cli_tools: small cat, cp, ls, and tree commands.
• example/lottie_manifest: reads Lottie JSON with cg-zhou/moon_lottie@0.3.0 and writes a text manifest. The renderer package is not used because it is wasm-gc-oriented.
• example/morm_query: writes SQL text using the synchronous query-builder surface of oboard/morm@0.3.12. It does not use Morm's async database engine APIs.

moon check
moon test
deno task test

• skills/miniio-portable-wasm: agent guidance and a small template for building WASIp1 executables with moonbit-community/miniio installed through moon add.

moon run demo