60 lines
1.4 KiB
Haskell
60 lines
1.4 KiB
Haskell
{-# LANGUAGE GeneralizedNewtypeDeriving, StandaloneDeriving,
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MultiParamTypeClasses #-}
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module Language.Epsilon.Types where
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import Text.Parsec
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import Data.Text (Text, pack, unpack)
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import Data.String (IsString, fromString)
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import Control.Monad.IO.Class (MonadIO)
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import Control.Monad.Except (MonadError)
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import Control.Monad.Trans.Except (ExceptT)
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type Ident = Text
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type Env = [(Ident, Value)]
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newtype EvalM a = EvalM { runEvalM :: ExceptT Error IO a }
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deriving (Functor, Applicative, Monad, MonadIO)
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deriving instance MonadError Error EvalM
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data PrimType = PrimFn | PrimMacro -- should args/result be evaluated?
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data Value
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= Snoc Value Value
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| Nil
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| Fn Ident Value
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| Macro Ident Value
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| Prim PrimType (Value -> EvalM Value)
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| Quote Value
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| Symbol Text
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| Int Int
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| Float Double
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| Str Text
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| Char Char
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instance Show Value where
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show (Snoc a d) = "(" ++ show a ++ " . " ++ show d ++ ")"
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show Nil = "()"
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show (Fn i v) = "(fn " ++ unpack i ++ " " ++ show v ++ ")"
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show (Macro i v) = "(macro " ++ unpack i ++ " " ++ show v ++ ")"
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show (Prim _ _) = "<primitive>"
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show (Quote v) = "'" ++ show v
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show (Symbol s) = unpack s
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show (Int i) = show i
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show (Float f) = show f
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show (Str s) = show s
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show (Char c) = show c
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instance IsString Value where
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fromString = Symbol . pack
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infixl 5 `Snoc`
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data Error
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= Unbound Ident
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| BadApply Value Value
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| TypeError Value
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| ReadError ParseError
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deriving Show
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