-- | Interpreter to compute a host-term.
module Language.Symantic.Interpreting.Host where

import Control.Monad

-- * Type 'HostI'

-- | Interpreter's data.
newtype HostI h = HostI { unHostI :: h }
instance Functor HostI where
	fmap f (HostI a) = HostI (f a)
instance Applicative HostI where
	pure = HostI
	(HostI f) <*> (HostI a) = HostI (f a)
instance Monad HostI where
	return = HostI
	(HostI a) >>= f = f a

-- | Interpreter.
host_from_term :: HostI h -> h
host_from_term = unHostI

hostI0 :: a -> HostI a
hostI0 = HostI

hostI1 :: (a -> b) -> HostI a -> HostI b
hostI1 = liftM

hostI2 :: (a -> b -> c) -> HostI a -> HostI b -> HostI c
hostI2 = liftM2

hostI3 :: (a -> b -> c -> d) -> HostI a -> HostI b -> HostI c -> HostI d
hostI3 = liftM3