ma, 2006-07-10 kello 14:26 +0200, Christian Maeder kirjoitti: ...
Maybe someone can extract a result from the old discussion about "Prelude function suggestions"
http://thread.gmane.org/gmane.comp.lang.haskell.libraries/1684/focus=1684 splitOn :: Eq a => a -- ^ seperator -> [a] -- ^ list to split -> [[a]]
Was the consensus that several functions should be added to the predule, wasn't it? splitOn :: Eq a => a -> [a] -> [[a]] breakWhere :: ([a] -> Bool) -> [a] -> [[a]] splitter :: ([a] -> (b,[a])) -> [a] -> [b] etc How about the following? 1) On split splitRE :: [a] -> [a] -> [[a]] where the first list is a regular exression like in vim-editor. E.g. splitRE "(<br>){2}" myHTMLString Ok, the type has to be String and there seems to be the regexlib, giving splitRE = splitRegex . mkRegex splitList :: Eq a => [a] -> [a] -> [[a]] where the first list is a sublist used to split the second list. Somehow, I more often need this one than the breakWhere -version (but still finding it helpfull if breakWhere is put somewhere). See also the suggestion 4. 2) Other string/list functions taking string/lists as argument and not just a char/item. E.g. intersperse [a] -> [a] -> [a] map ([a] -> [b]) -> [a] -> [b] replicate :: Int -> [a] -> [b] etc I'll guess the "list versions" of takeWhile, dropWhile and the other in this section (sublist, extracting) are almost the same as splitRE above, except that splitRE is only for strings. "List versions" of elem and notElem are subList and notSubList. Are these somewhere (couldn't spot them in 2 seconds and don't rembr)? 3) Reshaping of a list Couldn't spot this either in another 2 seconds... Sorry if this is somewhere. reshape :: Int -> Int -> [a] -> [[a]] reshape r c a = [map (a!!) [c*i..c*i+(c-1)] | i<-[0..(r-1)]] Prelude Text.Regex> reshape 2 4 [1..8] [[1,2,3,4],[5,6,7,8]] Prelude Text.Regex> reshape 4 2 [1..8] [[1,2],[3,4],[5,6],[7,8]] Ok, it seems that sometimes there is a need for a version where multidimensional matrices are reshaped freely to any dimension as long as there are the correct number of items... (but haven't thought how to implement this one). 4) splitRE again splitRE :: [a] -> String -> [a] -> [[a]] First one here is the regex pattern basic elements of type a. Second one is the regex string having place holders for the basic elements. Third one is the list over which the split is done. E.g. splitRE [1, 15, 3] "\(@1@2\){2}@3" myNumberList would make splits when it faces sublist [1,15,1,15,3]. Here, @ would be used as a metacharacter to place the list items in to the regular expression of type a. Other text.regex-functions for type a? br, Isto