error.log

warning: `part1` (bin "part1") generated 1 warning
error: could not compile `part1` due to previous error; 1 warning emitted
d474c7e06993:/workspace/day2/part1$ cargo run
   Compiling part1 v0.1.0 (/workspace/day2/part1)
error[E0283]: type annotations needed
  --> src/main.rs:26:26
   |
26 |     let mut dir_parser = alt((
   |         --------------   ^^^ cannot infer type for type parameter `E` declared on the function `alt`
   |         |
   |         consider giving `dir_parser` a type
   |
   = note: cannot satisfy `_: ParseError<&str>`
note: required by a bound in `alt`
  --> /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/nom-7.1.0/src/branch/mod.rs:71:28
   |
71 | pub fn alt<I: Clone, O, E: ParseError<I>, List: Alt<I, O, E>>(
   |                            ^^^^^^^^^^^^^ required by this bound in `alt`
help: consider specifying the type arguments in the function call
   |
26 |     let mut dir_parser = alt::<I, O, E, List>((
   |                             +++++++++++++++++

For more information about this error, try `rustc --explain E0283`.
error: could not compile `part1` due to previous error

main.rs

#![feature(stdin_forwarders)]

use nom::{
    branch::alt,
    bytes::complete::tag,
    character::complete::digit1,
    combinator::{map_res, value},
    sequence::separated_pair,
};

use std::io::{self};

#[derive(Clone, Debug)]
enum Direction {
    Forward,
    Down,
    Up,
}

struct Move {
    dir: Direction,
    count: i32,
}

fn main() {
    let mut dir_parser = alt((
        value(Direction::Forward, tag("forward")),
        value(Direction::Down, tag("down")),
        value(Direction::Up, tag("up")),
    ));

    let mut dec_parser = map_res(digit1, |s: &str| Ok(s.parse::<u32>().unwrap()));

    let mut move_parser = separated_pair(dir_parser, tag(" "), dec_parser);

    let mut moves = io::stdin().lines().map(|l| {
        let (rest, parsed) = move_parser(&l.unwrap())?;
        Ok(parsed)
    });

    println!("Hello, world!");
}