2009/3/11 Manlio Perillo
minh thu ha scritto:
[...] I suggest you try an alternative strategy. That altenrative strategy is twofold, just like you have quiz' and quiz'. This alternate strategy avoid pattern matching on strings (which would be cumbersome for a bit more complex syntax).
But for this specific case it is very compact and elegant (IMHO).
I would say it is difficult to see what you're doing in the code without the desciption you gave in the mail. But you're right, it's not the string pattern matching which is the problem. It is more the pair (Int, rest of the bytestring which can begin or not with ':')... Why not have quiz' accepting just the bytestring (and not the id value), and returning the (Int,[Int]) ?
[...] Now, given those two functions, try to apply them on your input string, feeding the next function application with the resulting string of the current application.
So, I should not split the string into lines?
See below.
An useful feature of my program is that it parses both an input like:
1: 1046323,2005-12-19
and 1: 1046323
If I write a parser from scratch I need to implement two separate functions.
I didn't think to that but nothing prevent you to write the second function I suggested to account for that case, or for an end of line (if can 'eat' the ':' from the input, you can also eat a newline). Thu