Data commit

Task/Update-a-configuration-file/Haskell/update-a-configuration-file-1.hs

@@ -0,0 +1,2 @@
+import Data.Char (toUpper)
+import qualified System.IO.Strict  as S

Task/Update-a-configuration-file/Haskell/update-a-configuration-file-2.hs

@@ -0,0 +1,27 @@
+data INI = INI { entries :: [Entry] } deriving Show
+
+data Entry = Comment String
+           | Field String String
+           | Flag String Bool
+           | EmptyLine
+
+instance Show Entry where
+  show entry = case entry of
+    Comment text -> "# " ++ text
+    Field f v    -> f ++ " " ++ v
+    Flag f True  -> f
+    Flag f False -> "; " ++ f
+    EmptyLine    -> ""
+
+instance Read Entry where
+  readsPrec _ s = [(interprete (clean " " s), "")]
+    where
+      clean chs = dropWhile (`elem` chs)
+      interprete ('#' : text) = Comment text
+      interprete (';' : f)= flag (clean " ;" f) False
+      interprete entry = case words entry of
+        []    -> EmptyLine
+        [f]   -> flag f True
+        f : v -> field f (unwords v)
+      field f = Field (toUpper <$> f)
+      flag f = Flag (toUpper <$> f)

Task/Update-a-configuration-file/Haskell/update-a-configuration-file-3.hs

@@ -0,0 +1,19 @@
+setValue :: String -> String -> INI -> INI
+setValue f v = INI . replaceOn (eqv f) (Field f v) . entries
+
+setFlag :: String -> Bool -> INI -> INI
+setFlag f v = INI . replaceOn (eqv f) (Flag f v) . entries
+
+enable f = setFlag f True
+disable f = setFlag f False
+
+eqv f entry = (toUpper <$> f) == (toUpper <$> field entry)
+  where field (Field f _) = f
+        field (Flag f _) = f
+        field _ = ""
+
+replaceOn p x lst = prev ++ x : post
+  where
+    (prev,post) = case break p lst of
+      (lst, []) -> (lst, [])
+      (lst, _:xs) -> (lst, xs)

Task/Update-a-configuration-file/Haskell/update-a-configuration-file-4.hs

@@ -0,0 +1,14 @@
+readIni :: String -> IO INI
+readIni file = INI . map read . lines <$> S.readFile file
+
+writeIni :: String -> INI -> IO ()
+writeIni file = writeFile file . unlines . map show . entries
+
+updateIni :: String -> (INI -> INI) -> IO ()
+updateIni file f = readIni file >>= writeIni file . f
+
+main = updateIni "test.ini" $
+  disable "NeedsPeeling" .
+  enable "SeedsRemoved" .
+  setValue "NumberOfBananas" "1024" .
+  setValue "NumberOfStrawberries" "62000"