This is already pretty nice. We are running 5 parsers on the input string, and the error message has made it much easier for us to track down that something is wrong with the boolean in the string.

Now luckily the input string is quite short, and there’s only one boolean we are trying to parse, so it’s simple to figure out exactly what went wrong. However, if the input was hundreds or thousands of characters long and there were multiple places we were parsing booleans then it wouldn’t be super helpful to know that somewhere a boolean failed to parse. We’d also like to know where exactly the parse failure happened.

Let’s see what it takes to do that.