# init - INI config file manipulation for OCaml

Init provides bidirectional codecs for INI files following Python's
configparser semantics. Define your configuration types once, and Init
handles both parsing and serialization.

## Features

- **Python-compatible**: Follows configparser semantics for maximum compatibility
- **Bidirectional codecs**: Define once, use for both decoding and encoding
- **Type-safe**: Strongly-typed configuration with compile-time guarantees
- **Multiline values**: Support for continuation lines via indentation
- **Interpolation**: Basic `%(name)s` and extended `${section:name}` variable substitution
- **DEFAULT section**: Automatic inheritance of default values
- **Optional values**: Graceful handling of missing configuration options

## Installation

```bash
opam install init
```

For parsing/encoding support, also install the bytesrw sub-library:

```bash
opam install init bytesrw
```

For Eio file system integration:

```bash
opam install init bytesrw eio bytesrw-eio
```

## Quick Start

```ocaml
(* Define your configuration type *)
type server_config = {
  host : string;
  port : int;
  debug : bool;
}

(* Define the codec *)
let server_codec = Init.Section.(
  obj (fun host port debug -> { host; port; debug })
  |> mem "host" Init.string ~enc:(fun c -> c.host)
  |> mem "port" Init.int ~enc:(fun c -> c.port)
  |> mem "debug" Init.bool ~dec_absent:false ~enc:(fun c -> c.debug)
  |> finish
)

let config_codec = Init.Document.(
  obj (fun server -> server)
  |> section "server" server_codec ~enc:Fun.id
  |> finish
)

(* Parse an INI file *)
let () =
  let ini = {|
[server]
host = localhost
port = 8080
debug = yes
|} in
  match Init_bytesrw.decode_string config_codec ini with
  | Ok config ->
      Printf.printf "Server: %s:%d (debug=%b)\n"
        config.host config.port config.debug
  | Error msg ->
      Printf.printf "Error: %s\n" msg
```

## Sub-libraries

- **init**: Core codec combinators (no dependencies)
- **init.bytesrw**: Parsing and encoding using bytesrw
- **init.eio**: Eio file system integration

## Documentation

See the [API documentation](https://ocaml.org/p/init/latest/doc/Init/index.html) for complete reference.

## License

ISC License. See [LICENSE](LICENSE) for details.