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Typeclass constraint should pick the OverloadedString type.

{-# LANGUAGE OverloadedStrings #-}
import Data.Text as T

class    NoDefault a      where noDefault :: a -> Text
instance NoDefault T.Text where noDefault = id

main = print (noDefault "Hello!")
default.hs:7:15:
    Ambiguous type variable `a0' in the constraints:
      (NoDefault a0) arising from a use of `noDefault'
                     at default.hs:7:15-23
      (Data.String.IsString a0) arising from the literal `"Hello!"'
                                at default.hs:7:25-32
    Probable fix: add a type signature that fixes these type variable(s)
    In the first argument of `print', namely `(noDefault "Hello!")'
    In the expression: print (noDefault "Hello!")
    In an equation for `main': main = print (noDefault "Hello!")
Trac metadata
Trac field Value
Version 7.4.1
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture
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