module Data.HList.String
    ( HString
    , hString
    )
    where

import Data.HList.Number
import Data.HList.Prelude
import Language.Haskell.TH
import Language.Haskell.TH.Quote


class HString s

instance HString HNil

instance HNat c => HString (HCons c s)

hString :: QuasiQuoter
hString = QuasiQuoter quoteStrExp quoteStrPat

quoteStrExp :: String -> ExpQ
quoteStrExp []     = varE (mkName "hNil")
quoteStrExp (c:cs) = appsE [ varE (mkName "hCons")
                           , hNatLiteralE (fromEnum c)
                           , quoteStrExp cs
                           ]

quoteStrPat :: String -> PatQ
quoteStrPat []     = varP (mkName "HNil")
quoteStrPat (c:cs) = conP (mkName "HCons") [ hNatLiteralP (fromEnum c)
                                           , quoteStrPat cs
                                           ]