os-string as a typeclass?

[domenkozar]

I've started writing a typeclass for all conversions:

class ToOS a b where
  toOS :: a -> b

instance ToOS ByteString OsString where
  toOS = OsString . toOS

instance ToOS PosixPath OsString where
  toOS = OsString 

instance ToOS ByteString PosixPath where
  toOS = coerce . BSS.toShort

instance ToOS PosixPath ByteString where
  toOS = BSS.fromShort . coerce

...

Then I've realized that some of the conversions would raise an exception like FilePath -> m PosixPath.

On top of that, a lot of these conversions are O(n) and now each library has to implement all the different interfaces.

Doesn't that smell like there should be a OsString typeclass for common operations just like we have Num?

class OsString a where
  pathSeparator :: a
  pathSeparators :: [a]
...

[hasufell]

Yes, I don't think this is generally a good idea. On top of that, the conversion ByteString -> WindowsString expects [Word16]. It is not a good interface.

When we're dealing with FilePath we don't want to make implicit choices. The user has to decide what is the right encoding.