Mercurial > 12ws.info2
annotate exercises/src/AdditionParser.hs @ 29:53732b9605c7
add AdditionParser
| author | Markus Kaiser <markus.kaiser@in.tum.de> |
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| date | Fri, 11 Jan 2013 00:49:48 +0100 |
| parents | |
| children |
| rev | line source |
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| 29 | 1 module AdditionParser where |
| 2 | |
| 3 import Data.Char | |
| 4 import Parser | |
| 5 | |
| 6 digit :: Parser Char Char | |
| 7 digit = one isDigit | |
| 8 | |
| 9 number :: Parser Char String | |
| 10 number = list1(one isDigit) | |
| 11 | |
| 12 addition :: Parser Char [String] | |
| 13 addition = number *** optional (item '+' *** addition >>> snd) >>> ints | |
| 14 where | |
| 15 ints (x, Just y) = x : y | |
| 16 ints (x, _) = [x] | |
| 17 | |
| 18 test = addition "2134+123+1+2+3" |