sem.icl

   1 implementation module sem
   2
   3 import qualified Data.Map as Map
   4 from Data.Func import $
   5 import Data.Maybe
   6 import Data.Either
   7 import Data.Functor
   8 import Control.Applicative
   9 import Control.Monad
  10 import Control.Monad.State
  11 import Control.Monad.Identity
  12 import Math.Random
  13 import Control.Monad.Trans
  14 import StdMisc
  15 from StdFunc import id, const, o
  16 import StdString
  17 import StdTuple
  18 import StdList
  19 import StdBool
  20
  21 from Text import class Text(concat), instance Text String
  22
  23 import AST
  24 from parse import :: ParserOutput, :: Error
  25
  26 :: Gamma :== ('Map'.Map String Type, [String])
  27 :: Env a :== StateT Gamma (Either SemError) a
  28 //StateT (Gamma -> Either SemError (a, Gamma))
  29
  30 //we need to redefine this even though it is in Control.Monad.State
  31 instance MonadTrans (StateT Gamma) where
  32     liftT m = StateT \s-> m >>= \a-> return (a, s)
  33
  34 get = gets id
  35
  36 sem :: AST -> SemOutput
  37 sem (AST vd fd) = case runStateT m ('Map'.newMap, getRandomStream 1) of
  38     Left e = Left [e]
  39     Right ((vds, fds), gamma) = Right ((AST vds fds), gamma)
  40 where
  41     m :: Env ([VarDecl], [FunDecl])
  42     m = mapM semVarDecl vd >>= \vds ->
  43         mapM semFunDecl fd >>= \fds ->
  44         pure (vds, fds)
  45
  46 semFunDecl :: FunDecl -> Env FunDecl
  47 semFunDecl fd=:(FunDecl p f args mt vds stmts) =
  48     saveGamma >>= \gamma ->
  49     (case mt of
  50         Nothing = let t = IdType f in putIdent f t >>| pure t
  51         Just t = putIdent f t >>| pure t) >>= \ft ->
  52     mapM_ (\a-> freshIdent >>= \fr-> putIdent a (IdType fr)) args >>|
  53     mapM_ semVarDecl vds >>|
  54     mapM_ (checkStmt $ resultType ft) stmts >>|
  55     restoreGamma gamma >>| pure fd
  56
  57 semVarDecl :: VarDecl -> Env VarDecl
  58 semVarDecl (VarDecl pos type ident ex) = unify type ex
  59     >>= \t-> putIdent ident t >>| (pure $ VarDecl pos t ident ex)
  60
  61 checkStmt ::Type Stmt -> Env Stmt
  62 checkStmt t (IfStmt c st se) = unify BoolType c >>| mapM (checkStmt t) st
  63     >>= \st1-> mapM (checkStmt t) se >>= \se1-> pure (IfStmt c st1 se1)
  64 checkStmt t w=:(WhileStmt c et) = unify BoolType c >>| mapM (checkStmt t) et
  65     >>= \et1-> pure w
  66 checkStmt t (AssStmt (VarDef ident fs) e) = undef
  67 checkStmt t r=:(FunStmt (FunCall f es)) = typeFun f es >>| pure r
  68 checkStmt VoidType r=:(ReturnStmt Nothing) = pure r
  69 checkStmt t r=:(ReturnStmt (Just e)) = unify t e >>| pure r
  70
  71 typeExpr :: Expr -> Env Type
  72 typeExpr (IntExpr _ _) = pure IntType
  73 typeExpr (CharExpr _ _) = pure CharType
  74 typeExpr (BoolExpr _ _) = pure BoolType
  75 typeExpr (Op1Expr p UnNegation expr) = unify BoolType expr
  76 typeExpr (Op1Expr p UnMinus expr) = unify IntType expr
  77 typeExpr (TupleExpr p (e1, e2)) = typeExpr e1
  78     >>= \t1-> typeExpr e2 >>= \t2-> pure $ TupleType (t1, t2)
  79 typeExpr (Op2Expr p e1 op e2)
  80 | isMember op [BiPlus, BiMinus, BiTimes, BiDivide, BiMod] =
  81         typeOp2 e1 e2 op [IntType] IntType
  82 | isMember op [BiEquals, BiUnEqual] =
  83         typeOp2 e1 e2 op [IntType, BoolType, CharType] BoolType
  84 | isMember op [BiLesser, BiGreater, BiLesserEq, BiGreaterEq] =
  85         typeOp2 e1 e2 op [IntType, CharType] BoolType
  86 | isMember op [BiAnd, BiOr] =
  87         typeOp2 e1 e2 op [BoolType] BoolType
  88 | op == BiCons = typeExpr e1 >>= \t1-> typeExpr e2
  89         >>= \t2-> unify (ListType t1) t2
  90 typeExpr (EmptyListExpr p) = freshIdent >>= \frsh-> let t = IdType frsh in
  91     putIdent frsh t >>| pure t
  92 typeExpr (FunExpr p (FunCall f es)) = typeFun f es
  93 typeExpr (VarExpr p (VarDef ident fs)) = gets (\(st, r)->'Map'.get ident st)
  94     >>= \mt->case mt of
  95         Nothing = liftT $ Left $ UndeclaredVariableError p ident
  96         Just t = unify t fs
  97
  98 typeOp2 :: Expr Expr Op2 [Type] Type -> Env Type
  99 typeOp2 e1 e2 op ts ret = typeExpr e1 >>= \t1-> typeExpr e2 >>= \t2->
 100     unify t1 t2 >>= \t3->if (isMember t3 ts) (pure ret)
 101         (liftT $ Left $ OperatorError (extrPos e1) op t3)
 102
 103 buildFunctionType :: String [Expr] -> Env Type
 104 buildFunctionType frsh [] = let t = IdType frsh in putIdent frsh t >>| pure t
 105 buildFunctionType frsh [e:es] = (->>) <$> typeExpr e <*> buildFunctionType frsh es
 106
 107 unifyApp :: Type [Expr] -> Env Type
 108 unifyApp t [] = pure t
 109 unifyApp (tf1 ->> tf2) [t1:ts] = unify tf1 t1 >>| unifyApp tf2 ts
 110 unifyApp t1 t2 = liftT $ Left $ UnifyError zero t1 (IdType "[expressions, FIXME]")
 111
 112 typeFun :: String [Expr] -> Env Type
 113 typeFun f es = gets (\(st, r)->'Map'.get f st) >>= \mt-> case mt of
 114     Nothing = freshIdent >>= \frsh-> buildFunctionType frsh es
 115         >>= \ft-> putIdent f ft >>| (pure $ IdType frsh)
 116     Just t = unifyApp t es
 117
 118 resultType :: Type -> Type
 119 resultType (_ ->> t) = resultType t
 120 resultType t = t
 121
 122 class unify a :: Type a -> Env Type
 123
 124 instance unify [FieldSelector] where
 125     unify t [] = pure t
 126     unify (ListType t) [FieldHd:fs] = unify t fs
 127     unify t=:(ListType _) [FieldTl:fs] = unify t fs
 128     unify (TupleType (t, _)) [FieldFst:fs] = unify t fs
 129     unify (TupleType (_, t)) [FieldSnd:fs] = unify t fs
 130     unify t [fs:_] = liftT $ Left $ FieldSelectorError zero t fs
 131
 132 instance unify Expr where
 133         unify (_ ->> _) e = liftT $ Left $ ParseError (extrPos e)
 134                         "Expression cannot be a higher order function. Yet..."
 135         unify VoidType e = liftT $ Left $ ParseError (extrPos e)
 136                         "Expression cannot be a Void type."
 137         unify (IdType _) e = liftT $ Left $ ParseError (extrPos e)
 138                         "Expression cannot be an polymorf type."
 139     unify VarType e = typeExpr e
 140     //we have to cheat to decorate the error, can be done nicer?
 141     unify t e = StateT $ \s0 -> let res = runStateT m s0 in case res of
 142         Left err = Left $ decErr e err
 143         Right t = Right t //note, t :: (Type, Gamma)
 144     where m = typeExpr e >>= \tex-> unify t tex
 145
 146 instance unify Type where
 147         unify IntType IntType = pure IntType
 148         unify BoolType BoolType = pure BoolType
 149         unify CharType CharType = pure CharType
 150     unify (IdType i) t=:(IdType j) = replace i t >>| pure t
 151     unify t (IdType i) = unify (IdType i) t
 152     unify (IdType i) t = replace i t >>| pure t
 153     unify (ListType t1) (ListType t2) = unify t1 t2 >>| (pure $ ListType t1)
 154     unify (ta1 ->> ta2) (tb1 ->> tb2) = unify ta1 tb1 >>= \ta-> unify ta2 tb2
 155         >>= \tb-> pure (ta ->> tb)
 156         unify t1 t2 = liftT $ Left $ UnifyError zero t1 t2
 157
 158 instance zero Pos where
 159         zero = {line=0,col=0}
 160
 161 decErr :: Expr SemError -> SemError
 162 decErr e (UnifyError _ t1 t2) = UnifyError (extrPos e) t1 t2
 163 decErr e (FieldSelectorError _ t fs) = FieldSelectorError (extrPos e) t fs
 164 decErr e (ParseError _ s) = ParseError (extrPos e) s
 165 decErr e err = err
 166
 167 dc2 :: Expr (Either SemError a) -> Either SemError a
 168 dc2 e (Right t) = Right t
 169 dc2 e (Left err) = Left err
 170
 171 extrPos :: Expr -> Pos
 172 extrPos (VarExpr p _) = p
 173 extrPos (Op2Expr p _ _ _) = p
 174 extrPos (Op1Expr p _ _) = p
 175 extrPos (IntExpr p _) = p
 176 extrPos (CharExpr p _) = p
 177 extrPos (BoolExpr p _) = p
 178 extrPos (FunExpr p _) = p
 179 extrPos (EmptyListExpr p) = p
 180 extrPos (TupleExpr p _) = p
 181
 182 instance toString Gamma where
 183         toString (mp, _) = concat
 184                 [concat [k, ": ", toString v, "\n"]\\(k, v) <- 'Map'.toList mp]
 185
 186 getRandomStream :: Int -> [String]
 187 getRandomStream i = genIdents $ filter (isAlpha o toChar) (genRandInt i)
 188     where
 189         genIdents r = let (ic, r2) = splitAt 5 r in [toString ic: genIdents r2]
 190
 191 freshIdent :: Env String
 192 freshIdent = get >>= \(st, [ident:rest])-> put (st, rest)
 193     >>| case 'Map'.get ident st of
 194         Nothing = pure ident
 195         _       = freshIdent
 196
 197 putIdent :: String Type -> Env Void
 198 putIdent i t = gets (\(st, r)->'Map'.get i st) >>= \mt -> case mt of
 199     Nothing = modify (\(st, r)->('Map'.put i t st, r))
 200     Just t2 = unify t t2 >>= \t3-> modify (\(st, r)->('Map'.put i t3 st, r))
 201
 202 replace :: String Type -> Env Void
 203 replace ident type = get >>= \(st, fr)->put ('Map'.fromList $
 204         map (itupdate ident type) ('Map'.toList st), fr)
 205     where
 206         itupdate :: String Type (String, Type) -> (String, Type)
 207         itupdate ident newtype ov=:(key, IdType type) = if (ident == type)
 208             (key, newtype) ov
 209         itupdate ident newtype (key, TupleType (t1, t2))
 210         # (_, t1) = itupdate ident newtype (key, t1)
 211         # (_, t2) = itupdate ident newtype (key, t2)
 212         = (key, TupleType (t1, t2))
 213         itupdate ident newtype (key, ListType t1)
 214         # (_, t1) = itupdate ident newtype (key, t1)
 215         = (key, ListType t1)
 216         itupdate _ _ k = k
 217
 218 instance toString SemError where
 219     toString (ParseError p e) = concat [
 220         toString p,"SemError: ParseError: ", e]
 221     toString (Error e) = "SemError: " +++ e
 222     toString (UnifyError p t1 t2) = concat [
 223         toString p,
 224         "SemError: Cannot unify types. Expected: ",
 225         toString t1, ". Given: ", toString t2]
 226     toString (FieldSelectorError p t fs) = concat [
 227         toString p,
 228         "SemError: Cannot select ", toString fs, " from type: ",
 229         toString t]
 230     toString (OperatorError p o t) = concat [
 231         toString p,
 232         "SemError: No ", toString o, " for type ",
 233         toString t]
 234     toString (UndeclaredVariableError p ident) = concat [
 235         toString p, "SemError: identifier: ", ident, " undefined."]
 236
 237 saveGamma :: Env Gamma
 238 saveGamma = get
 239
 240 restoreGamma :: Gamma -> Env Void
 241 restoreGamma g = put g