Source code

 1 | fn lol(a: Box<for<'a> fn(x:&'a u32)->()>) {
   |                ↑
 2 | }

Location: line 1, column 15

What I got

"Function Type. The type of a free standing function." spanning the whole generic argument of the Box.

What I expected

"The type of a free standing function" can contain many tricky things inside it. I expect some individual tokens within that type to be selectable.

What I expected

Brief explanation of type annotations (and possibly link to book).

Source code

 0 | fn main() {
 1 |   let mut rdr: Box<io::Read> = match input {
   |              ↑-------------↑
 2 |     "-" => Box::new(io::stdin()),
 3 |     _   => Box::new(fs::File::open(input).unwrap()),
 4 |   };
 5 | }

Location: line 1, column 13

Generated links don't work. Here is a link I've just generated:
https://jrvidal.github.io/?code=fn%20main()%7B%7D
I get error 404 when I try to access it.

It looks like the correct link should be
https://jrvidal.github.io/explaine.rs/?code=fn%20main()%7B%7D

i.e. recognize #[derive(...)], #[cfg(...)], etc. and link to the Rust reference.

This is awesome for learning!

I wonder if it could be possible to somehow combine this with rust-patterns to also show common idiomatic constructs used throughout Rust programs?

?Sized Trait Bound

A bound that expresses that the Sized trait may not be implemented for a given type parameter.

is what the website says. I think it should say "may or may not" instead, like in the Rust book.

What I expected

:: is the path separator (https://doc.rust-lang.org/book/appendix-02-operators.html)

Source code

 4 |     let list_tables = ListTablesOperation::new().limit(50).build(dynamo_config);
   |                                          ↑

 9 | }

Location: line 4, column 41

What I expected

It would be super awesome to have a hint for ' lifetime annotations, since they're non-trivial to google for when you don't know what they're called.

Source code

I hope I'm getting the terminology right here. For the example code, I used an example from https://doc.rust-lang.org/1.9.0/book/lifetimes.html

0 | struct Foo<'a> {
  |         /* ↑ lifetime annotation */
1 |   x: &'a i32,
  |    /* ↑ lifetime annotation */
2 | }

What I expected

Please see https://users.rust-lang.org/t/a-question-about-syntax/52790/2 & https://doc.rust-lang.org/stable/book/ch19-03-advanced-traits.html#default-generic-type-parameters-and-operator-overloading.

Source code

 0 | struct Foo<T = String>(T);
   |              ↑
 1 | 
 2 | fn main() {
 3 |   let x: Foo = Foo(String::from("thunk"));
 4 |   let y: Foo<i32> = Foo(17);
 5 | }

Location: line 0, column 13

Adding an extra &edition=2018 param to "Open in Playground" button will activate the recent Rust 2018 edition by default.

Tapping on text doesn't seem to work.

I'm on Chrome for Android.
Chrome v80.0.3987.162
Android 9