baseline parsing/evalHEADmaster

1 files changed, 16 insertions, 13 deletions

diff --git a/src/Hint/Eval.hs b/src/Hint/Eval.hs
index 48f7b46..36628dc 100644
--- a/src/Hint/Eval.hs
+++ b/src/Hint/Eval.hs
@@ -2,31 +2,34 @@ module Hint.Eval where
 
 import           Control.Applicative ((<|>))
 import qualified Data.Map            as M
-import           Hint.Parser         (Value (..))
+import           Data.Maybe          (fromJust)
+import           Hint.Data
 
-type Ident = String
-type Env = M.Map Ident Value
+type Env = M.Map Identifier Expr
 
 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)]
+basic = Scope mempty
 
-enter :: Scope -> Env -> Scope
-enter (Scope es) e = Scope (e : es)
+enter :: Env -> Scope -> Scope
+enter e (Scope es) = Scope (e : es)
 
 leave :: Scope -> Scope
 leave (Scope [] )      = error "bad"
 leave (Scope (_ : es)) = Scope es
 
-scopeLookup :: Ident -> Scope -> Maybe Value
+scopeLookup :: Identifier -> Scope -> Maybe Expr
 scopeLookup _ (Scope [])       = Nothing
 scopeLookup i (Scope (e : es)) = M.lookup i e <|> scopeLookup i (Scope es)
+
+eval :: Scope -> Expr -> Maybe Expr
+eval _ (Literal l) = Literal <$> pure l
+eval s (Ident i) = scopeLookup i s
+eval scope (Bind name val rest) =
+  eval (enter (M.fromList [(name, fromJust $ eval scope val)]) scope) rest
+eval s (If cond a b) = do
+  Literal (Boolean c) <- eval s cond
+  if c then eval s a else eval s b