conversions-0.0.2: src/Data/Conversions/FromType.hs

-- | Conversions from type-level values
--
module Data.Conversions.FromType where

import           Data.Conversions
import           Data.Kind                      ( Type )
import           Data.Proxy                     ( Proxy(..) )
import           Data.Text                      ( Text )
import           GHC.TypeLits            hiding ( natVal )
import           GHC.TypeNats                   ( natVal )
import           Numeric.Natural                ( Natural )
import           Prelude

class FromType a (b :: Type) where
  fromType :: b

-- These instances are not polymorphic in the last parameter so to
-- avoid over-lapping instances
--
instance (KnownNat nat) => FromType nat Natural where
  fromType = natVal (Proxy @nat)

instance (KnownSymbol symbol) => FromType symbol String where
  fromType = symbolVal (Proxy @symbol)

instance (KnownSymbol symbol) => FromType symbol Text where
  fromType = convert @Text @String $ fromType @symbol