Multisplit: Difference between revisions

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@@ Line 676: / Line 676: @@
 Or as a fold:
-<lang haskell>import Data.Maybe (isNothing, fromJust)
+<lang haskell>multiSplit :: [String] -> String -> [(String, String, Int)]
-import Data.List (find, isPrefixOf)
-multiSplit :: [String] -> String -> [(String, String, Int)]
 multiSplit ds s =
   let lng = length s
-      (tokens, parts, offset) =
+      (ts, ps, o) =
         foldl
           (\(tokens, parts, offset) (c, i) ->
               let inDelim = offset > i
-                  mb =
+              in case (if inDelim
-                    if inDelim
+                         then Nothing
-                      then Nothing
+                         else find (`isPrefixOf` drop i s) ds) of
-                      else find (`isPrefixOf` drop i s) ds
+                   Just x -> ([], mappend parts [(tokens, x, i)], i + length x)
-              in if isNothing mb
+                   Nothing ->
-                   then ( mappend
+                     ( mappend
-                            tokens
+                         tokens
-                            (if inDelim
+                         (if inDelim
-                               then []
+                            then []
-                               else [c])
+                            else [c])
-                        , parts
+                     , parts
-                        , offset)
+                     , offset))
-                   else ( []
-                        , mappend parts [(tokens, fromJust mb, i)]
-                        , i + length (fromJust mb)))
           ([], [], 0)
           (zip s [0 .. lng])
-  in mappend parts [(tokens, [], lng)]
+  in mappend ps [(ts, [], lng)]
 main :: IO ()
-main = print $ multiSplit ["==", "!=", "="] "a!===b=!=c"
+main = print $ multiSplit ["==", "!=", "="] "a!===b=!=c"</lang>
-</lang>
 {{Out}}
 <pre>[("a","!=",1),("","==",3),("b","=",6),("","!=",7),("c","",10)]</pre>