Feature: error printer

[mindplay-dk]

What do you think about including a formatError function?

I wrote a function that takes the input string and a Failure instance, and prints out the surrounding +/- n lines with line-numbers etc.

I don't know if it's wise to include this in the library, since parser errors aren't the only type of errors you'd want to print - though, on the other hand, if the function was just something like formatError(input: string, offset: number, expectation: string), then this could be used to inject whatever expectation you want, to print out semantic errors and so on.

Not 100% sure if this is a good idea, as error formats can be quite different in different projects - but on the other hand, it might be nice to have something you can use just to get your project started and get something useful on the screen without doing a lot of ground work?

Up to you, but I do have something I could PR, if you'd like. 🙂