implement Trait?

[droundy]

Now that implement Trait is stable, could you use it both for code and examples in order to simplify the API?

[Marwes]

There are some examples that uses impl Trait but I have held of using it in the library itself to enable combine to be used on older compilers.

Thanks to https://docs.rs/combine/3.6.2/combine/macro.parser.html I don't see a large win in readability from updating to impl Trait so weighing the pros and cons I rather stick with supporting older rustc's for the time being.

[Marwes]

Unfortunately issues such as rust-lang/rust#42940 causes rustc to error in some cases where it shouldn't so this might not be possible to fix in 4.x