PrimPrintable.hs

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeFamilies #-}

module Descript.Misc.Build.Write.Print.PrimPrintable
  ( PrimPrintable (..)
  ) where

import Descript.Misc.Build.Write.Print.APrint
import Descript.Misc.Summary
import Data.Ratio
import Data.Monoid
import Data.Text (Text)

-- | A primitive value inside of an AST leaf which can be printed back
-- into source text. Instances would implement 'Printable', but they
-- don't have annotations, so they implement this instead.
class (Summary a) => PrimPrintable a where
  -- | Prints the primitive value.
  pprim :: (APrint r) => a -> r

instance PrimPrintable Char where
  pprim = plex . show

instance PrimPrintable Int where
  pprim = plex . show

instance PrimPrintable Integer where
  pprim = plex . show

instance PrimPrintable Float where
  pprim = plex . show

instance PrimPrintable Double where
  pprim = plex . show

instance (a ~ Char) => PrimPrintable [a] where
  pprim = plex . show

instance PrimPrintable Text where
  pprim = plex . show

instance (PrimPrintable a) => PrimPrintable (Ratio a) where
  pprim x
    | denomPrint == "1" = numPrint
    | otherwise = numPrint <> "/" <> denomPrint -- Or just 'plex' everything?
    where numPrint = pprim $ numerator x
          denomPrint = pprim $ denominator x