add 'Interpreter' with basic infrastructure

ccntrq · Jan 8, 2018 · 56c8237 · 56c8237
1 parent fe4ab13
commit 56c8237
Showing 1 changed file with 38 additions and 0 deletions.
diff --git a/src/Interpreter.hs b/src/Interpreter.hs
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+module Interpreter (interpret) where
+
+import Object
+import Stmt
+import Expr
+
+import Control.Monad.Except
+import Control.Monad.State
+
+
+data InterpreterState = InterpreterState deriving (Show)
+
+data InterpreterError = InterpreterError String deriving (Show)
+
+type Interpreter a = ExceptT InterpreterError (StateT InterpreterState IO) a
+
+interpret :: [Stmt] -> IO ()
+interpret stmts = do 
+    _ <- runInterpreter InterpreterState $ interpretStmts stmts
+    return ()
+
+runInterpreter :: InterpreterState -> Interpreter a -> IO (Either InterpreterError a)
+runInterpreter st i = evalStateT (runExceptT i) st
+
+
+interpretStmts :: [Stmt] -> Interpreter ()
+interpretStmts [] = return ()
+interpretStmts (s:stmts) = execute s >> interpretStmts stmts
+
+execute :: Stmt -> Interpreter ()
+execute (Expression expr) = evaluate expr >>= liftIO . print >> return ()
+execute _ = error "fuck"
+
+
+evaluate :: Expr -> Interpreter Object
+evaluate (Literal obj) = return obj
+evaluate _ = error "fuck"
+