Help typing a not-so-generic combinator

[basro]

I want to write a custom combinator that is not generic over the input and output type but I'm having a lot of trouble writing the output type.

What I wanted to do:

fn example_combinator(prefix: &'static str) -> impl Parser<_, _, _> // What types go here?
{
  (prefix, take_while(0.., '_')).recognize()
}

As a work around I can do this:

fn example_combinator2<'s>(prefix: &'static str) -> impl Fn(&mut &'s str) -> PResult<&'s str> {
    move |input| (prefix, take_while(0.., '_')).recognize().parse_next(input)
}

[epage]

fn example_combinator(prefix: &'static str) -> impl Parser<&str, &str, ContextError>` // What types go here?
{
  (prefix, take_while(0.., '_')).recognize()
}

With Parser<I, O, E>

• I maps to the input to your Fn
• O maps to the first (or only) parameter for PResult
• E maps to the second parameter to PResult which is defaulted to be ContextError

[basro]

Thanks for your answer and this great library!