{-# LANGUAGE NoImplicitPrelude #-}
-- declarations of builtin functions and data types used by the compiler
module Internals where

undefined :: forall (a :: Type) . a

primFix :: forall (a :: Type) . (a -> a) -> a

data Unit = TT
data String
data Empty (a :: String)

-- TODO: generate?
data Tuple0 = Tuple0
data Tuple1 a = Tuple1 a
data Tuple2 a b = Tuple2 a b
data Tuple3 a b c = Tuple3 a b c
data Tuple4 a b c d = Tuple4 a b c d
data Tuple5 a b c d e = Tuple5 a b c d e


-- ... TODO

-- builtin used for overlapping instances
parEval :: forall a -> a -> a -> a

type family EqCT (t :: Type) (a :: t) (b :: t)     -- equality constraints
type family T2 a b      -- conjuction of constraints

-- builtin conjuction of constraint witnesses
t2C :: Unit -> Unit -> Unit

-- builtin type constructors
data Int
data Word
data Float
data Char

data Bool = False | True

data Ordering = LT | EQ | GT

-- builtin primitives
primIntToWord       :: Int   -> Word
primIntToFloat      :: Int   -> Float
primCompareInt      :: Int   -> Int   -> Ordering
primCompareWord     :: Word  -> Word  -> Ordering
primCompareFloat    :: Float -> Float -> Ordering
primCompareString   :: String -> String -> Ordering
primNegateInt       :: Int   -> Int
primNegateWord      :: Word  -> Word
primNegateFloat     :: Float -> Float
primAddInt          :: Int   -> Int   -> Int
primSubInt          :: Int   -> Int   -> Int
primModInt          :: Int   -> Int   -> Int
primSqrtFloat       :: Float -> Float
primRound           :: Float -> Int


primIfThenElse :: Bool -> a -> a -> a
primIfThenElse True  a b = a
primIfThenElse False a b = b

-- fromInt is needed for integer literal
class Num a where
  fromInt :: Int -> a
  compare :: a -> a -> Ordering
  negate :: a -> a

instance Num Int where
  fromInt = \x -> x
  compare = primCompareInt
  negate  = primNegateInt
instance Num Word where
  fromInt = primIntToWord
  compare = primCompareWord
  negate  = primNegateWord
instance Num Float where
  fromInt = primIntToFloat
  compare = primCompareFloat
  negate  = primNegateFloat