Update only specific field of specific item (data) in List from YAML

Question

I don't like the logic to update [Repository] list here because I need to map whole list to change only specific field of specific node, I especially don't like that I need to provide all other fields in changing node alike (location x) etc... Major trouble there is that if I will edit data model I will be forced to edit a lot of code where I use it like this.

hashupdate :: String -> String -> IO ()
hashupdate hash rep =
 withConfig $ \ymlx ->
 let ymlprocess = ifSo $ do
 rsdata <- yDecode ymlx :: IO [Repository]
 let ed = map enR rsdata
 where enR x = if rep == (location x)
 then (Repository (location x)
 (branches x)
 (upstream x)
 (enabled x)
 (clean x)
 (post_rebuild x)
 (syncGroup x)
 (Just hash))
 else x
 yEncode ymlx ed
 in doesFileExist ymlx >>= ymlprocess

The other definitions used there is here:

data Repository = Repository { location :: String
 , branches :: [String]
 , upstream :: String
 , enabled :: Maybe Bool
 , clean :: Maybe Bool
 , post_rebuild :: Maybe [String]
 , syncGroup :: Maybe String
 , hash :: Maybe String
 } deriving (Show, Eq)
yEncode :: ToJSON iToJSONable => FilePath -> iToJSONable -> IO()
yEncode fnm dat = do
 let bs = Data.Yaml.encode dat
 BS.writeFile fnm bs

Answer 1

I don't like that I need to provide all other fields in changing node alike (location x) etc...

You can "update" a field of a record like so:

where enR x = if rep == location x then x { hash = Just hash } else x

I would recommend against names like fnm, dat, ed, enR, etc. You should also use consistent casing (postRebuild instead of post_rebuild).