forked from GitHub/gf-core
118 lines
2.9 KiB
Haskell
118 lines
2.9 KiB
Haskell
module Ident where
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import Operations
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-- import Monad
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data Ident =
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IC String -- raw identifier after parsing, resolved in Rename
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| IW -- wildcard
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-- below this line: internal representation never returned by the parser
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| IV (Int,String) -- variable
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| IA (String,Int) -- argument of cat at position
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| IAV (String,Int,Int) -- argument of cat with bindings at position
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deriving (Eq, Ord, Show, Read)
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prIdent :: Ident -> String
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prIdent i = case i of
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IC s -> s
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IV (n,s) -> s ++ "_" ++ show n
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IA (s,j) -> s ++ "_" ++ show j
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IAV (s,b,j) -> s ++ "_" ++ show b ++ "_" ++ show j
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IW -> "_"
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(identC, identV, identA, identAV, identW) =
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(IC, IV, IA, IAV, IW)
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-- normal identifier
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-- ident s = IC s
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-- to mark argument variables
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argIdent 0 (IC c) i = identA (c,i)
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argIdent b (IC c) i = identAV (c,b,i)
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-- used in lin defaults
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strVar = identA ("str",0)
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-- wild card
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wildIdent = identW
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isWildIdent :: Ident -> Bool
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isWildIdent = (== wildIdent)
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newIdent = identC "#h"
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mkIdent :: String -> Int -> Ident
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mkIdent s i = identV (i,s)
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varIndex :: Ident -> Int
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varIndex (IV (n,_)) = n
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varIndex _ = -1 --- other than IV should not count
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-- refreshing identifiers
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type IdState = ([(Ident,Ident)],Int)
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initIdStateN :: Int -> IdState
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initIdStateN i = ([],i)
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initIdState :: IdState
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initIdState = initIdStateN 0
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lookVar :: Ident -> STM IdState Ident
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lookVar a@(IA _) = return a
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lookVar x = do
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(sys,_) <- readSTM
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stm (\s -> maybe (Bad ("cannot find" +++ show x +++ prParenth (show sys)))
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return $
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lookup x sys >>= (\y -> return (y,s)))
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refVar :: Ident -> STM IdState Ident
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----refVar IW = return IW --- no update of wildcard
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refVar x = do
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(_,m) <- readSTM
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let x' = IV (m, prIdent x)
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updateSTM (\ (sys,mx) -> ((x, x'):sys, mx + 1))
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return x'
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refVarPlus :: Ident -> STM IdState Ident
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----refVarPlus IW = refVar (identC "h")
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refVarPlus x = refVar x
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{-
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------------------------------
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-- to test
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refreshExp :: Exp -> Err Exp
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refreshExp e = err Bad (return . fst) (appSTM (refresh e) initState)
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refresh :: Exp -> STM State Exp
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refresh e = case e of
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Atom x -> lookVar x >>= return . Atom
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App f a -> liftM2 App (refresh f) (refresh a)
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Abs x b -> liftM2 Abs (refVar x) (refresh b)
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Fun xs a b -> do
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a' <- refresh a
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xs' <- mapM refVar xs
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b' <- refresh b
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return $ Fun xs' a' b'
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data Exp =
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Atom Ident
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| App Exp Exp
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| Abs Ident Exp
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| Fun [Ident] Exp Exp
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deriving Show
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exp1 = Abs (IC "y") (Atom (IC "y"))
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exp2 = Abs (IC "y") (App (Atom (IC "y")) (Atom (IC "y")))
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exp3 = Abs (IC "y") (Abs (IC "z") (App (Atom (IC "y")) (Atom (IC "z"))))
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exp4 = Abs (IC "y") (Abs (IC "y") (App (Atom (IC "y")) (Atom (IC "z"))))
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exp5 = Abs (IC "y") (Abs (IC "y") (App (Atom (IC "y")) (Atom (IC "y"))))
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exp6 = Abs (IC "y") (Fun [IC "x", IC "y"] (Atom (IC "y")) (Atom (IC "y")))
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exp7 = Abs (IL "8") (Atom (IC "y"))
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-}
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