haskell - ¿Cómo consigo que funcione la extensión de lenguaje OverloadedStrings?

ghc overloaded-strings

Question

He habilitado cadenas sobrecargadas, pero no puedo hacer que funcionen:

$ cat overloadedstrings.hs
{-# LANGUAGE OverloadedStrings #-}
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as BL
lazy :: BL.ByteString
lazy = "I''m a lazy ByteString"
strict :: B.ByteString
strict = "I''m a strict ByteString"
$ ghci
GHCi, version 6.12.1: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude> :l overloadedstrings.hs
[1 of 1] Compiling Main ( overloadedstrings.hs, interpreted )
overloadedstrings.hs:7:7:
No instance for (Data.String.IsString BL.ByteString)
arising from the literal `"I''m a lazy ByteString"''
at overloadedstrings.hs:7:7-29
Possible fix:
add an instance declaration for
(Data.String.IsString BL.ByteString)
In the expression: "I''m a lazy ByteString"
In the definition of `lazy'': lazy = "I''m a lazy ByteString"
overloadedstrings.hs:10:9:
No instance for (Data.String.IsString B.ByteString)
arising from the literal `"I''m a strict ByteString"''
at overloadedstrings.hs:10:9-33
Possible fix:
add an instance declaration for (Data.String.IsString B.ByteString)
In the expression: "I''m a strict ByteString"
In the definition of `strict'': strict = "I''m a strict ByteString"
Failed, modules loaded: none.

¿ IsString dónde importo las instancias de ByteString para ByteString ? ¿No debería esto suceder automáticamente? ¿Qué estoy haciendo mal?

Answer 1

.Char8 importar los módulos .Char8 , como Data.ByteString.Char8 y Data.ByteString.Lazy.Char8