How to create a parser? I get error "Required: fastparse.ParsingRun[Any]"

[halloleo]

I try to get started with a minimal parser. In a Scala file for scala-cli file I have:

//> using dep com.lihaoyi::fastparse::3.1.0

import fastparse._

def parser[_: P] = 
    P( "hello" )

@main
def theWork() =
    println(fastparse.parse("hello", parser(_)))

But on P( "hello" ) I get "Required: fastparse.ParsingRun[Any]".

What's going wrong?