Following the tutorial and got error after the "parsing digits" section

[0x7FFFFFFFFFFFFFFF]

I'm new to Rust and and I'm following the tutorial. After the "parsing digits" section, I have the following files.

.
├── Cargo.lock
├── Cargo.toml
├── src
│   └── main.rs
└── test.foo

test.foo

3

main.rs

use chumsky::prelude::*;

fn main() {
    let src = std::fs::read_to_string("test.foo").unwrap();

    println!("{:?}", parser().parse(src));
}

#[derive(Debug)]
enum Expr{
    Num(f64),
    Var(String),

    Neg(Box<Expr>),
    Add(Box<Expr>, Box<Expr>),
    Sub(Box<Expr>, Box<Expr>),
    Mul(Box<Expr>, Box<Expr>),
    Div(Box<Expr>, Box<Expr>),

    Call(String, Vec<Expr>),
    Let {
        name: String,
        rhs: Box<Expr>,
        then: Box<Expr>,
    },
    Fn {
        name: String,
        args: Vec<String>,
        body: Box<Expr>,
        then: Box<Expr>,
    },
}

fn parser() -> impl Parser<char, Expr, Error = Simple<char>>{

    filter(|c: &char| c.is_ascii_digit()).map(|c| Expr::Num(c.to_digit(10).unwrap() as f64))
}

Cargo.toml

[package]
name = "foo"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
chumsky = "0.6.0"

When I run it, I got the following error:

error[E0277]: the trait bound `chumsky::Stream<'_, char, std::ops::Range<usize>, _>: From<String>` is not satisfied
 --> src\main.rs:6:31
  |
6 |     println!("{:?}", parser().parse(src));
  |                               ^^^^^ the trait `From<String>` is not implemented for `chumsky::Stream<'_, char, std::ops::Range<usize>, _>`
  |
  = help: the following implementations were found:
            <chumsky::Stream<'a, T, std::ops::Range<usize>, Box<(dyn Iterator<Item = (T, std::ops::Range<usize>)> + 'a)>> as From<&'a [T]>>
            <chumsky::Stream<'a, T, std::ops::Range<usize>, Box<(dyn Iterator<Item = (T, std::ops::Range<usize>)> + 'a)>> as From<[T; N]>>
            <chumsky::Stream<'a, char, std::ops::Range<usize>, Box<(dyn Iterator<Item = (char, std::ops::Range<usize>)> + 'a)>> as From<&'a str>>
  = note: required because of the requirements on the impl of `Into<chumsky::Stream<'_, char, std::ops::Range<usize>, _>>` for `String`

I can't figure out where is the problem. Could anyone give me some help? Thanks.

Btw, I'm using Rust 1.57 on Windows.

c:\>cargo --version
cargo 1.57.0 (b2e52d7ca 2021-10-21)
c:\>rustc --version
rustc 1.57.0 (f1edd0429 2021-11-29)

[zesterer]

Hi!

This isn't your fault, I think the problem is that you're relying on the latest stable version of the crate while the tutorial is written against the master branch. The master branch has some new features that aren't in the latest stable version.

In the case of this error, you can use src.as_str() to borrow the String as a &str.

However, it might be easier to have your project depend on the master branch for now, because there are some later parts of the tutorial that you'll run into similar issues with if you're only using the latest stable version. You can do that with the following in your Cargo.toml:

chumsky = { git = "https://github.com/zesterer/chumsky.git" }

[0x7FFFFFFFFFFFFFFF]

Thanks, it works now.