Haskell 如何将字符串解析为GADT
我正在尝试在Haskell中实现组合逻辑,我想为该语言编写解析器。我无法通过Parsec让解析器工作。基本问题是,我需要一种方法来确保解析器返回的对象类型正确。有人对如何做到这一点有什么创造性的想法吗Haskell 如何将字符串解析为GADT,haskell,parsec,gadt,combinatory-logic,Haskell,Parsec,Gadt,Combinatory Logic,我正在尝试在Haskell中实现组合逻辑,我想为该语言编写解析器。我无法通过Parsec让解析器工作。基本问题是,我需要一种方法来确保解析器返回的对象类型正确。有人对如何做到这一点有什么创造性的想法吗 {-# Language GeneralizedNewtypeDeriving #-} import qualified Data.Map as Map import qualified Text.ParserCombinators.Parsec as P import Text.Parsec.
{-# Language GeneralizedNewtypeDeriving #-}
import qualified Data.Map as Map
import qualified Text.ParserCombinators.Parsec as P
import Text.Parsec.Token (parens)
import Text.ParserCombinators.Parsec ((<|>))
import Control.Applicative ((<$>), (<*>), (*>), (<*))
data CTree = CApp CTree CTree | CNode String deriving (Eq, Read)
instance Show CTree where
show c@(CApp x y) = showL c
where showL (CApp x' y')= "(" ++ showL x' ++ " " ++ showR y' ++ ")"
showL (CNode s) = s
showR (CApp x' y') = "(" ++ showL x' ++ " " ++ showR y' ++ ")"
showR (CNode s) = s
show (CNode s) = s
-- | Parser
parseC :: String -> Maybe CTree
parseC s = extract$ P.parse expr "combinator_string" s
where extract (Right r) = Just r
extract (Left e) = Nothing
expr :: P.CharParser () CTree
expr = P.try (CApp <$> (CApp <$> term <*> term) <*> expr)
<|> P.try (CApp <$> term <*> term)
<|> term
term = P.spaces *> (node <|> P.string "(" *> expr <* P.string ")")
node :: P.CharParser () CTree
node = CNode <$> (P.many1 $ P.noneOf "() ")
eval (CApp (CNode "I") x) = x
eval (CApp (CApp (CApp (CNode "S") f) g) x) =
(CApp (CApp f x) (CApp g x))
eval (CApp (CApp (CApp (CNode "B") f) g) x) =
(CApp f (CApp g x))
eval (CApp (CApp (CApp (CNode "C") f) g) x) =
(CApp (CApp f x) g)
eval x = x
{-#语言泛化newtypederiving}
导入符合条件的数据。映射为映射
将限定的Text.ParserCombinators.Parsec作为P导入
导入Text.Parsec.Token(参数)
导入Text.ParserCombinators.Parsec(())
导入控制。应用程序((),(),(*>),(可能是CTree)
parseC s=extract$P.parse expr“combinator_string”s
其中提取(右r)=仅r
提取(左e)=无
expr::P.CharParser()CTree
expr=P.try(CApp术语expr)
P.try(CApp术语)
学期
term=P.spaces*>(node P.string)(“*>expr我强烈主张解析为单类型表示,然后应用类型检查/细化阶段将其转换为类型化(GADT)表示。关于一般思想的最佳教程可能来自
滑雪演算的表示形式可能如下所示
data TyComb t where
TyS :: TyComb ((a -> b -> c) -> (a -> b) -> a -> c)
TyK :: TyComb (a -> b -> a)
TyI :: TyComb (a -> a)
TyApp :: TyComb (a -> b) -> TyComb a -> TyComb b
evalTyComb :: TyComb t -> t
evalTyComb TyS = \x y z -> (x z) (y z)
evalTyComb TyK = const
evalTyComb TyI = id
evalTyComb (TyApp a b) = (evalTyComb a) (evalTyComb b)
您可能希望使用存在式或更高级别的延续(不太可能,因为这里可能需要非指示类型)。