# Gleam File Streams
This Gleam library provides access to Erlang's file streams for reading and
writing files. If you don't require streaming behavior then consider using
[`simplifile`](https://hex.pm/packages/simplifile) instead.
This library only supports the Erlang target.
[](https://hex.pm/packages/file_streams)
[](https://hexdocs.pm/file_streams/)
## Example
Add this library to your project:
```sh
gleam add file_streams
```
The following code writes data to a file using a write stream, reads it back in
using a binary file stream, then reads it again with a text file stream.
```gleam
import file_streams/read_stream
import file_streams/read_stream_error
import file_streams/read_text_stream
import file_streams/write_stream
import gleam/bit_array
// Write file
let assert Ok(ws) = write_stream.open("test.txt")
let assert Ok(Nil) = write_stream.write_string(ws, "Hello, world!\n")
let assert Ok(Nil) = write_stream.write_bytes(ws, <<"12":utf8>>)
let assert Ok(Nil) = write_stream.close(ws)
// Read file as a binary stream
let assert Ok(rs) = read_stream.open("test.txt")
let assert Ok(bytes) = read_stream.read_bytes(rs, 14)
let assert Ok("Hello, world!\n") = bit_array.to_string(bytes)
let assert Ok([49, 50]) = read_stream.read_list(rs, read_stream.read_uint8, 2)
let assert Error(read_stream_error.EndOfStream) = read_stream.read_bytes(rs, 1)
let assert Ok(Nil) = read_stream.close(rs)
// Read file as a text stream so UTF-8 characters and lines can be read
let assert Ok(rts) = read_text_stream.open("test.txt")
let assert Ok("Hello") = read_text_stream.read_chars(rts, 5)
let assert Ok(", world!\n") = read_text_stream.read_line(rts)
let assert Ok("12") = read_text_stream.read_line(rts)
let assert Error(read_stream_error.EndOfStream) = read_text_stream.read_line(rts)
let assert Ok(Nil) = read_text_stream.close(rts)
```
Further documentation can be found at <https://hexdocs.pm/file_streams/>.
## License
This library is published under the MIT license, a copy of which is included.
