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v1.hs

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+--- NOTE: IS NOT COMPLETED ---
+
+type Symb = String
+infixl 4 :@:
+
+data Type = Boo
+          | Type :-> Type
+          | BoxT Symb Type -- is type required ??
+    deriving (Read,Show,Eq)
+
+-- TODO: integrate into match
+data SymbType = SymbIn -- simple 'argument'
+              | SymbOut -- exported from inside function to outer context by export
+              | SymbRef -- In + Out
+
+data CtxType = PreviousCtx
+             | NewCtx
+
+data Term = Fls
+          | Tru
+          | Var Symb
+          | Box SymbType Symb Type
+          | Export Symb Type
+          | Term :@: Term
+          | Match Term Term Term -- match _ : T then _ else _
+          -- Box s t (variable place) = Match SymbIn 
+          deriving (Read,Show)
+
+type Ctx = Map Symb Term
+
+assign :: Term -> Term -> Maybe Ctx
+
+assign Fls Fls = Just []
+assign Tru Tru = Just []
+assign (Idx i) (Idx j) | i == j = Just []
+assign (Box x _) t = Just [t] -- TODO: remember name
+assign (left :@: right) (left' :@: right') = do ctxLeft <- assign left left' -- TODO: ??
+                                                ctxRight <- assign right right'
+                                                Just $ ctxLeft ++ ctxRight 
+-- assign (Match pattern t doThen deElse) term = case assign pattern term of -- TODO: ??
+--                                                 Just ctx -> doThen
+--                                                 Nothing -> doElse
+assign _ _ = Nothing
+
+-- need to extend context in some way
+-- context effect ??
+
+-- TODO
+subst :: Ctx -> Term -> Term
+
+-- TODO
+oneStep :: Term -> Maybe Term
+oneStep _ = Nothing
+
+-- TODO
+whnf :: Term -> Term
+whnf u = maybe u whnf (oneStep u)