docs(calculator_example): bumps `chumsky` crate from 0.9.0 to 0.10.0 #474

your-diary · 2025-03-26T15:06:17Z

#439 added a simple calculator example to the book, and the example used chumsky crate as a parser combinator library.

Recently, chumsky v0.10.0 was released and it contains relatively many breaking changes. So I try to upgrade the dependency in this PR.

Please note the crate is only used in the example (I checked $ rg chumsky at the root of the repository).

References

… which is only used in the example

codspeed-hq · 2025-03-26T15:08:20Z

CodSpeed Performance Report

Merging #474 will not alter performance

_{Comparing your-diary:docs/bump_dependency_of_simple_calculator_example (162dbea) with master (ea83d46)}

Summary

✅ 6 untouched benchmarks

codecov · 2025-03-26T15:08:40Z

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 49.26%. Comparing base (ea83d46) to head (162dbea).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #474      +/-   ##
==========================================
- Coverage   49.31%   49.26%   -0.05%     
==========================================
  Files          33       33              
  Lines        2054     2054              
==========================================
- Hits         1013     1012       -1     
- Misses       1041     1042       +1

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your-diary · 2025-03-26T15:14:22Z

examples/calculator.rs

@@ -80,7 +80,9 @@ impl Expr {

 #[allow(clippy::let_and_return)]
 /* ANCHOR: parser */
-fn parser() -> impl Parser<Token, Expr, Error = Simple<Token>> {
+fn parser<'src>(
+) -> impl Parser<'src, &'src [Token], Expr, chumsky::extra::Err<chumsky::error::Simple<'src, Token>>>


ref: migration guide

The Parser trait has now gained a lifetime parameter, representing the lifetime of the input. Most of the time you just want to have your parser function be generic over it, like fn my_parser<'src>() -> impl Parser<'src, I, O> { ... }.

The I parameter of Parser<'src, I, O> now refers to the entire input, not just the token type. For example, if your parser previously parsed Tokens, your input type will likely be &'src [Token].

The optional E parameter of Parser<'src, I, O, E>, which previously indicated the error type, has been renamed as the 'Extra' parameter, which continues to specify the error type, along with other features like state, context, etc. There is a convenient short-hand in the form of the the extra::Err type alias, which preserves the same behaviour.

your-diary · 2025-03-26T15:16:36Z

examples/calculator.rs

-                    .repeated(),
-            )
-            .foldl(|lhs, (op, rhs)| match op {
+            .foldr(atom, |_op, rhs| Expr::Neg(Box::new(rhs)));


then(X).foldr(Y) in v0.9.0 corresponds to foldr(X, Y) in v0.10.0: zesterer/chumsky#746

your-diary · 2025-03-26T15:17:03Z

examples/calculator.rs

+            .foldr(atom, |_op, rhs| Expr::Neg(Box::new(rhs)));
+
+        let binary_1 = unary.clone().foldl(
+            just(Token::Multiply)


then(X).foldl(Y) in v0.9.0 corresponds to foldl(X, Y) in v0.10.0: zesterer/chumsky#746

your-diary · 2025-03-26T15:17:31Z

examples/calculator.rs

+            },
+        );
+
+        let binary_2 = binary_1.clone().foldl(


then(X).foldl(Y) in v0.9.0 corresponds to foldl(X, Y) in v0.10.0: zesterer/chumsky#746

your-diary · 2025-03-26T15:19:15Z

examples/calculator.rs

@@ -156,7 +152,7 @@ fn main() {
    }

    //parses the tokens to construct an AST
-    let ast = match parser().parse(tokens) {
+    let ast = match parser().parse(&tokens).into_result() {


Parser::parse() now returns ParseResult instead of std::result::Result so I added .into_result() to preserve the old behavior.

your-diary · 2025-03-26T15:20:12Z

examples/calculator.rs


        binary_2
    })
-    .then_ignore(end())


ref: migration guide

Parsers are no longer lazy by default. Previously, one had to add .then_ignore(end()) to the top-level parser to 'force' it to keep consuming tokens until the end of the input. This is no longer the case, calling parser.parse(...) will produce an error if all input is not consumed.

your-diary · 2025-03-26T15:44:33Z

The CI failed:

/Users/runner/.cargo/bin/cargo test --workspace --verbose --features forbid_unsafe

<snip>

error: package `half v2.5.0` cannot be built because it requires rustc 1.81 or newer, while the currently active rustc version is 1.74.0
Either upgrade to rustc 1.81 or newer, or use
cargo update half@2.5.0 --precise ver
where `ver` is the latest version of `half` supporting rustc 1.74.0
Error: The process '/Users/runner/.cargo/bin/cargo' failed with exit code 101

but I don't understand the reason...

A similar command

$ cargo +1.74.0 build --workspace --verbose --features forbid_unsafe

succeeded on my local environment.

jeertmans · 2025-03-26T16:21:13Z

Hi @your-diary! Thanks for your PR :-)

The CI failed:

/Users/runner/.cargo/bin/cargo test --workspace --verbose --features forbid_unsafe

<snip>

error: package `half v2.5.0` cannot be built because it requires rustc 1.81 or newer, while the currently active rustc version is 1.74.0
Either upgrade to rustc 1.81 or newer, or use
cargo update half@2.5.0 --precise ver
where `ver` is the latest version of `half` supporting rustc 1.74.0
Error: The process '/Users/runner/.cargo/bin/cargo' failed with exit code 101

but I don't understand the reason...

A similar command

$ cargo +1.74.0 build --workspace --verbose --features forbid_unsafe

succeeded on my local environment.

You may need to update the lock file (Cargo.lock).

your-diary · 2025-03-27T12:06:48Z

@jeertmans
Hi!

You may need to update the lock file (Cargo.lock).

Cargo.lock is listed in .gitignore, so when I execute git add -f Cargo.lock, it is staged as a new file.

Am I missing something?

your-diary · 2025-03-27T12:42:19Z

@jeertmans

It seems the failure is reproducible in master branch:

$ docker run -it --rm alpine sh

$ apk add curl libgcc git
$ curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
$ . "$HOME/.cargo/env"
$ rustup install 1.74.0
$ git clone 'https://github.com/maciejhirsz/logos.git'
$ cd logos
$ cargo +1.74.0 test --workspace --verbose --features forbid_unsafe

Possible cause: This repository doesn't have Cargo.lock, so latest compatible crates are fetched in CI. And v2.5.0 of half crate was recently released. The release note says "MSRV has been changed to 1.81".

A similar command
$ cargo +1.74.0 build --workspace --verbose --features forbid_unsafe
succeeded on my local environment.

I'm sorry this was incorrect. I should have executed cargo +1.74.0 TEST instead of cargo +1.74.0 BUILD. When I retried with cargo +1.74.0 test, it failed as in the CI.

jeertmans · 2025-03-30T07:44:55Z

@jeertmans

It seems the failure is reproducible in master branch:
$ docker run -it --rm alpine sh
$ apk add curl libgcc git
$ curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
$ . "$HOME/.cargo/env"
$ rustup install 1.74.0
$ git clone 'https://github.com/maciejhirsz/logos.git'
$ cd logos
$ cargo +1.74.0 test --workspace --verbose --features forbid_unsafe
Possible cause: This repository doesn't have Cargo.lock, so latest compatible crates are fetched in CI. And v2.5.0 of half crate was recently released. The release note says "MSRV has been changed to 1.81".
A similar command
$ cargo +1.74.0 build --workspace --verbose --features forbid_unsafe
succeeded on my local environment.
I'm sorry this was incorrect. I should have executed cargo +1.74.0 TEST instead of cargo +1.74.0 BUILD. When I retried with cargo +1.74.0 test, it failed as in the CI.

Yes, you are right, and I totally forgot we didn’t include a lock file, which we should definitely do for better testing about versions. Could you include a lock file with your PR?

…/tests

your-diary · 2025-03-30T08:27:23Z

@jeertmans

Yes, you are right, and I totally forgot we didn’t include a lock file, which we should definitely do for better testing about versions. Could you include a lock file with your PR?

Of course!

I executed the following command.

$ cargo +1.74.0 clean
$ cargo +1.74.0 test --workspace --verbose --features forbid_unsafe
$ cargo +1.74.0 test --workspace --verbose
$ cargo +1.74.0 build --workspace --verbose --features forbid_unsafe
$ cargo +1.74.0 build --workspace --verbose
$ git add -f Cargo.lock

Now CI passed except for codecov/project :)
Should I do something else to make the check pass?

docs(calculator_example): bumps chumsky crate from 0.9.0 to 0.10.0,…

35d64ec

… which is only used in the example

your-diary commented Mar 26, 2025

View reviewed changes

your-diary marked this pull request as ready for review March 26, 2025 15:23

build(cargo): adds missing Cargo.lock to enable reproducible builds…

162dbea

…/tests

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docs(calculator_example): bumps `chumsky` crate from 0.9.0 to 0.10.0 #474

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docs(calculator_example): bumps chumsky crate from 0.9.0 to 0.10.0 #474

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docs(calculator_example): bumps chumsky crate from 0.9.0 to 0.10.0 #474

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docs(calculator_example): bumps `chumsky` crate from 0.9.0 to 0.10.0 #474

docs(calculator_example): bumps `chumsky` crate from 0.9.0 to 0.10.0 #474