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module Hint.Eval where
import Control.Applicative ((<|>))
import qualified Data.Map as M
import Hint.Parser (Value (..))
type Ident = String
type Env = M.Map Ident Value
data Scope = Scope
{ env :: [Env] }
deriving (Show, Eq)
defaultEnv :: Env
defaultEnv = M.fromList [("pi", VInt 3), ("version", VString "0.1")]
basic :: Scope
basic = Scope (pure defaultEnv)
next :: Env
next = M.fromList [("ident", VInt 12), ("pi", VInt 4)]
enter :: Scope -> Env -> Scope
enter (Scope es) e = Scope (e : es)
leave :: Scope -> Scope
leave (Scope [] ) = error "bad"
leave (Scope (_ : es)) = Scope es
scopeLookup :: Ident -> Scope -> Maybe Value
scopeLookup _ (Scope []) = Nothing
scopeLookup i (Scope (e : es)) = M.lookup i e <|> scopeLookup i (Scope es)
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