Question

https://github.com/xich/scotty/issues/26

https://github.com/xich/scotty/pull/27

class ScottyString a where
  toContent :: a -> Content
  toText :: a -> T.Text
  fromScotty :: T.Text -> a

instance ScottyString B.ByteString where
  toContent bs = ContentBuilder (fromByteString bs)
  toText bs = toText $ BL.fromChunks [bs]
  fromScotty = B.concat . BL.toChunks . fromScotty

instance ScottyString BL.ByteString where
  toContent bs = ContentBuilder (fromLazyByteString bs)
  toText = decodeUtf8
  fromScotty = encodeUtf8

instance ScottyString T.Text where
  toContent = toContent . encodeUtf8
  toText = id
  fromScotty = id

instance ScottyString String where
  toContent = toContent . T.pack
  toText = T.pack
  fromScotty = T.unpack

For me it works fine, but old code is breaked… Because now there is no default type for some functions.

How add default type for this typeclass (for example, Text)?

Answer 1

BTW, I’ve started an almost identical Stringable typeclass on hackage: http://hackage.haskell.org/package/stringable

Written because I got tired of having to remember how to convert everything to each other.