Anonymous user
Tokenize a string: Difference between revisions
Undo revision 115192 by 86.145.79.157 (talk) revert Haskell entry; new version uses non-standard library and deleted many examples
(Added two solutions for Bracmat) |
(Undo revision 115192 by 86.145.79.157 (talk) revert Haskell entry; new version uses non-standard library and deleted many examples) |
||
Line 548:
=={{header|Haskell}}==
The necessary operations are unfortunately not in the standard library (yet), but simple to write:
import Data.List▼
<lang haskell>splitBy :: (a -> Bool) -> [a] -> [[a]]
main = putStrLn $ intercalate "." $ splitOn "," "Hello,How,Are,You,Today"▼
splitBy _ [] = []
</lang>▼
splitBy f list = first : splitBy f (dropWhile f rest) where
(first, rest) = break f list
splitRegex :: Regex -> String -> [String]
joinWith :: [a] -> [[a]] -> [a]
joinWith d xs = concat $ List.intersperse d xs
-- "concat $ intersperse" can be replaced with "intercalate" from the Data.List in GHC 6.8 and later
-- using regular expression to split:
putStrLn $ joinWith "." $ splitRegex (mkRegex ",") $ "Hello,How,Are,You,Today"</lang>
Tokenizing can also be realized by using unfoldr and break:
<lang Haskell>*Main> mapM_ putStrLn $ takeWhile (not.null) $ unfoldr (Just . second(drop 1). break (==',')) "Hello,How,Are,You,Today"
Hello
How
Are
You
▲Today</lang>
* You need to import the modules Data.List and Control.Arrow
As special cases, splitting / joining by white space and by newlines are provided by the Prelude functions <tt>words</tt> / <tt>unwords</tt> and <tt>lines</tt> / <tt>unlines</tt>, respectively.
=={{header|Groovy}}==
| |||