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Literal.hs
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Literal.hs
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{-# LANGUAGE GADTs, RankNTypes #-}
module Literal where
--------------------------------------------------------------------
data Literal
= LChar { unChar::Char } -- 'x'
| LString {unString::String} -- "abc" "\nabc"
| LInt { unInt :: Int } -- 5 , -5
| LRational {unRational :: Rational} -- 4%5
| LInteger {unInteger :: Integer } -- 0234704370329473294
| LFloat { unFloat::Float } -- 2.3 , 0.5 , -3.4
| LDouble { unDouble::Double} -- 2.3 , 0.5 , -3.4
| LBool {unBool:: Bool } -- True , False
| LUnit -- ()
| LEntity {unEntity:: Int} -- [10009]
deriving (Eq,Ord)
compareL (LChar x) (LChar y) = compare x y
compareL (LString x) (LString y) = compare x y
compareL (LInt x) (LInt y) = compare x y
compareL (LRational x) (LRational y) = compare x y
compareL (LInteger x) (LInteger y) = compare x y
compareL (LFloat x) (LFloat y) = compare x y
compareL (LDouble x) (LDouble y) = compare x y
compareL (LBool x) (LBool y) = compare x y
compareL LUnit LUnit = EQ
compareL (LEntity x) (LEntity y) = compare x y
compareL x y = error("Wrong types in comparison: "++show x++" does not have the same type as "++show y)
instance Show Literal where
show (LChar c) = show c
show (LString s) = show s
show (LInt n) = show n
show (LRational n) = show n
show (LInteger n) = show n
show (LFloat n) = show n
show (LDouble n) = show n
show (LBool t) = show t
show LUnit = "()"
show (LEntity n) = "["++show n++"]"
-- liftInteger is an attempt to implement toInteger, which always returns an LInteger
-- object, then if you operate on it in a context that demands (say a Float) then
-- it is lazily lifted to a float. So there is implict coercion on Integer,
-- but no other type.
liftInteger :: String -> (forall t . Num t => (t -> t -> t)) -> Literal -> Literal -> Literal
liftInteger s f (LInteger x) (LInt y) = LInt (f (fromInteger x) y)
liftInteger s f (LInt x) (LInteger y) = LInt (f x (fromInteger y))
liftInteger s f (LInteger x) (LFloat y) = LFloat (f (fromInteger x) y)
liftInteger s f (LFloat x) (LInteger y) = LFloat (f x (fromInteger y))
liftInteger s f (LInteger x) (LDouble y) = LDouble (f (fromInteger x) y)
liftInteger s f (LDouble x) (LInteger y) = LDouble (f x (fromInteger y))
liftInteger s f (LInteger x) (LRational y) = LRational (f (fromInteger x) y)
liftInteger s f (LRational x) (LInteger y) = LRational (f x (fromInteger y))
liftInteger s f x y = error ("Incompatible types for overloaded opertor "++s)
instance Num Literal where
fromInteger n = LInt(fromInteger n)
(+) (LInt n) (LInt m) = LInt(n+m)
(+) (LFloat n) (LFloat m) = LFloat(n+m)
(+) (LDouble n) (LDouble m) = LDouble(n+m)
(+) (LRational n) (LRational m) = LRational(n+m)
(+) (LInteger n) (LInteger m) = LInteger(n+m)
(+) x y = liftInteger "(+)" (+) x y
(*) (LInt n) (LInt m) = LInt(n*m)
(*) (LFloat n) (LFloat m) = LFloat(n*m)
(*) (LDouble n) (LDouble m) = LDouble(n*m)
(*) (LRational n) (LRational m) = LRational(n*m)
(*) (LInteger n) (LInteger m) = LInteger(n*m)
(*) x y = liftInteger "(*)" (*) x y
(-) (LInt n) (LInt m) = LInt(n-m)
(-) (LFloat n) (LFloat m) = LFloat(n-m)
(-) (LDouble n) (LDouble m) = LDouble(n-m)
(-) (LRational n) (LRational m) = LRational(n-m)
(-) (LInteger n) (LInteger m) = LInteger(n-m)
(-) x y = liftInteger "(-)" (-) x y
abs (LInt n) = LInt(abs n)
abs (LFloat n) = LFloat(abs n)
abs (LDouble n) = LDouble(abs n)
abs (LInteger n) = LInteger(abs n)
abs (LRational n) = LRational(abs n)
abs x = error ("Non Num in instance (Num Literal) for 'abs'")
negate (LInt n) = LInt(negate n)
negate(LFloat n) = LFloat(negate n)
negate(LDouble n) = LDouble(negate n)
negate (LInteger n) = LInteger(negate n)
negate (LRational n) = LRational(negate n)
negate x = error ("Non Num in instance (Num Literal) for 'negate'")
signum (LInt n) = LInt(signum n)
signum (LFloat n) = LFloat(signum n)
signum (LDouble n) = LDouble(signum n)
signum (LInteger n) = LInteger(signum n)
signum (LRational n) = LRational(signum n)
signum x = error ("Non Num in instance (Num Literal) for 'signum'")
{-
toLiteral :: HasRep t => t -> Literal
toLiteral t = repToLiteral repOf t
repToLiteral :: Rep t -> t -> Literal
repToLiteral Char n = LChar n
repToLiteral String n = LString n
repToLiteral Int n = LInt n
repToLiteral Rational n = LRational n
repToLiteral Integer n = LInteger n
repToLiteral Float n = LFloat n
repToLiteral Double n = LDouble n
repToLiteral Bool t = LBool t
repToLiteral Unit n = LUnit
-}
data Lit t where
LitChar :: Char -> Lit Char
LitString :: String -> Lit String
LitInt :: Int -> Lit Int
LitRational :: Rational -> Lit Rational
LitInteger :: Integer -> Lit Integer
LitFloat :: Float -> Lit Float
LitDouble :: Double -> Lit Double
LitBool :: Bool -> Lit Bool
LitUnit :: Lit ()
litToLiteral:: Lit t -> Literal
litToLiteral x = case x of
LitChar n -> LChar n
LitString n -> LString n
LitInt n -> LInt n
LitRational n -> LRational n
LitInteger n -> LInteger n
LitFloat n -> LFloat n
LitDouble n -> LDouble n
LitBool n -> LBool n
LitUnit -> LUnit
evalLit:: Lit t -> t
evalLit x = case x of
LitChar n -> n
LitString n -> n
LitInt n -> n
LitRational n -> n
LitInteger n -> n
LitFloat n -> n
LitDouble n -> n
LitBool n -> n
LitUnit -> ()