module Language.Haskell.Tools.Refactor.Predefined.DataToNewtype (dataToNewtype) where

import Language.Haskell.Tools.Refactor
import Control.Reference

tryItOut moduleName = tryRefactor (\_ -> localRefactoring dataToNewtype) moduleName ""

dataToNewtype :: Domain dom => LocalRefactoring dom
dataToNewtype = return . (modDecl & annList .- changeDeclaration)

changeDeclaration :: Decl dom -> Decl dom
changeDeclaration dd@(DataDecl DataKeyword ctx declHead (AnnList [ConDecl name (AnnList [arg])]) derivs)
  = declNewtype .= mkNewtypeKeyword $ dd
changeDeclaration decl = decl