TH.hs

{-
 - Copyright (C) 2019  Koz Ross <koz.ross@retro-freedom.nz>
 -
 - This program is free software: you can redistribute it and/or modify
 - it under the terms of the GNU General Public License as published by
 - the Free Software Foundation, either version 3 of the License, or
 - (at your option) any later version.
 -
 - This program is distributed in the hope that it will be useful,
 - but WITHOUT ANY WARRANTY; without even the implied warranty of
 - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 - GNU General Public License for more details.
 -
 - You should have received a copy of the GNU General Public License
 - along with this program.  If not, see <http://www.gnu.org/licenses/>.
 -}

{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications #-}

module Data.Finitary.TH where

import Foreign.Storable (Storable, sizeOf)
import Language.Haskell.TH (Q, Type(..), TyLit(..), Exp(..), Lit(..))

charCardinality :: Q Type
charCardinality = pure . LitT . NumTyLit . fromIntegral . (+ 1) . fromEnum $ maxBound @Char

cardinalityOf :: forall a . (Storable a) => Q Type
cardinalityOf = pure . LitT . NumTyLit $ 2 ^ ( sizeOf @a undefined * 8 )

adjustmentOf :: forall a . (Integral a, Bounded a) => Q Exp
adjustmentOf = pure . LitE . IntegerL . (+ 1) . fromIntegral @_ @Integer $ maxBound @a