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
  20 from Text import class Text(concat), instance Text String
  21
  22 import AST
  23 from parse import :: ParserOutput, :: Error
  24
  25 :: Gamma :== ('Map'.Map String Type, [String])
  26 :: Env a :== StateT Gamma (Either SemError) a
  27
  28 //we need to redefine this even though it is in Control.Monad.State
  29 instance MonadTrans (StateT Gamma) where
  30     liftT m = StateT \s-> m >>= \a-> return (a, s)
  31
  32 get = gets id
  33
  34 getRandomStream :: Int -> [String]
  35 getRandomStream i = genIdents $ filter (isAlpha o toChar) (genRandInt i)
  36         where
  37                 genIdents r = let (ic, r) = splitAt 5 r in [toString ic: genIdents r]
  38
  39 freshIdent :: Gamma -> (String, Gamma)
  40 freshIdent (st, [ident:rest]) = case 'Map'.get ident st of
  41         Nothing = (ident, (st, rest))
  42         _ = freshIdent (st, rest)
  43
  44 putIdent :: String Type -> Env Void
  45 putIdent i t = gets (\(st, r)->'Map'.get i st) >>= \mt -> case mt of
  46     Nothing = modify (\(st, r)->('Map'.put i t st, r))
  47     Just t2 = unify t t2 >>= \t3-> modify (\(st, r)->('Map'.put i t3 st, r))
  48
  49 instance toString SemError where
  50         toString (ParseError p e) = concat [
  51                 toString p,"SemError: ParseError: ", e]
  52         toString (Error e) = "SemError: " +++ e
  53         toString (UnifyErrorStub t1 t2) = toString (UnifyError {line=0,col=0} t1 t2)
  54         toString (UnifyError p t1 t2) = concat [
  55                 toString p,
  56                 "SemError: Cannot unify types. Expected: ",
  57                 toString t1, ". Given: ", toString t2]
  58
  59 sem :: AST -> SemOutput
  60 sem (AST vd fd) = case evalStateT m ('Map'.newMap, getRandomStream 0) of
  61     Left e = Left [e]
  62     Right (vds, fds) = Right (AST vds fds)
  63 where
  64     m :: Env (([VarDecl], [FunDecl]))
  65     m = (mapM semVarDecl vd) >>= \vds ->
  66         mapM semFunDecl fd >>= \fds ->
  67         pure (vds, fds)
  68
  69
  70
  71 splitEithers :: [Either a b] -> Either [a] [b]
  72 splitEithers [] = Right []
  73 splitEithers [Right x:xs] = splitEithers xs >>= \rest->Right [x:rest]
  74 splitEithers xs = Left $ [x\\(Left x)<-xs]
  75
  76 semFunDecl :: FunDecl -> Env FunDecl
  77 semFunDecl f = pure f
  78
  79 semVarDecl :: VarDecl -> Env VarDecl
  80 semVarDecl (VarDecl pos type ident ex) = unify type ex
  81     >>= \t-> putIdent ident t >>| (pure $ VarDecl pos t ident ex)
  82
  83 typeExpr :: Expr -> Env Type
  84 typeExpr (IntExpr _ _) = pure IntType
  85 typeExpr (CharExpr _ _) = pure CharType
  86 typeExpr (BoolExpr _ _) = pure BoolType
  87 typeExpr (Op1Expr p UnNegation expr) = unify BoolType expr
  88 typeExpr (Op1Expr p UnMinus expr) = unify IntType expr
  89 typeExpr (TupleExpr p (e1, e2)) = typeExpr e1
  90     >>= \t1-> typeExpr e2 >>= \t2-> pure $ TupleType (t1, t2)
  91 //Int
  92 typeExpr (Op2Expr p e1 BiPlus e2) = unify IntType e1 >>| unify IntType e2
  93 typeExpr (Op2Expr p e1 BiMinus e2) = unify IntType e1 >>| unify IntType e2
  94 typeExpr (Op2Expr p e1 BiTimes e2) = unify IntType e1 >>| unify IntType e2
  95 typeExpr (Op2Expr p e1 BiDivide e2) = unify IntType e1 >>| unify IntType e2
  96 typeExpr (Op2Expr p e1 BiMod e2) = unify IntType e1 >>| unify IntType e2
  97 //bool, char of int
  98 typeExpr (Op2Expr p e1 BiEquals e2) = typeExpr e1 >>= \t1 -> unify t1 e2
  99     >>| pure BoolType //todo, actually check t1 in Char,Bool,Int
 100 typeExpr (Op2Expr p e1 BiUnEqual e2) = typeExpr (Op2Expr p e1 BiEquals e2)
 101 //char of int
 102 typeExpr (Op2Expr p e1 BiLesser e2) = typeExpr e1 >>= \t1 -> unify t1 e2
 103     >>| pure BoolType //todo, actually check t1 in Char, Int
 104 typeExpr (Op2Expr p e1 BiGreater e2) = typeExpr (Op2Expr p e1 BiLesser e2)
 105 typeExpr (Op2Expr p e1 BiLesserEq e2) = typeExpr (Op2Expr p e1 BiLesser e2)
 106 typeExpr (Op2Expr p e1 BiGreaterEq e2) = typeExpr (Op2Expr p e1 BiLesser e2)
 107 //bool
 108 typeExpr (Op2Expr p e1 BiAnd e2) = unify BoolType e1 >>| unify BoolType e2
 109 typeExpr (Op2Expr p e1 BiOr e2) = unify BoolType e1 >>| unify BoolType e2
 110 //a
 111 typeExpr (Op2Expr p e1 BiCons e2) = typeExpr e1 >>= \t1-> typeExpr e2
 112     >>= \t2-> unify (ListType t1) t2
 113 //typeExpr (FunExpr p FunCall) = undef
 114 typeExpr (EmptyListExpr p) = pure $ ListType IntType //we'll need quantified types
 115 //typeExpr (VarExpr Pos VarDef) = undef //when checking var-expr, be sure to
 116     //put the infered type in the context
 117
 118 class unify a :: Type a -> Env Type
 119
 120 instance unify Expr where
 121         unify (_ ->> _) e = liftT $ Left $ ParseError (extrPos e)
 122                         "Expression cannot be a higher order function. Yet..."
 123         unify VoidType e = liftT $ Left $ ParseError (extrPos e)
 124                         "Expression cannot be a Void type."
 125         unify (IdType _) e = liftT $ Left $ ParseError (extrPos e)
 126                         "Expression cannot be an polymorf type."
 127     unify VarType e = typeExpr e
 128     //we have to cheat to decorate the error, can be done nicer?
 129     unify t e = StateT $ \s0 -> let res = runStateT m s0 in case res of
 130         Left err = Left $ decErr e err
 131         Right t = Right t //note, t :: (Type, Gamma)
 132     where m = typeExpr e >>= \tex-> unify t tex
 133
 134 instance unify Type where
 135         unify IntType IntType = pure IntType
 136         unify BoolType BoolType = pure BoolType
 137         unify CharType CharType = pure CharType
 138     unify (ListType t1) (ListType t2) = unify t1 t2
 139         unify t1 t2 = liftT $ Left $ UnifyError zero t1 t2
 140
 141 instance zero Pos where
 142         zero = {line=0,col=0}
 143
 144 decErr :: Expr SemError -> SemError
 145 decErr e (UnifyError _ t1 t2) = UnifyError (extrPos e) t1 t2
 146 decErr e (ParseError _ s) = ParseError (extrPos e) s
 147 decErr e err = err
 148
 149 dc2 :: Expr (Either SemError a) -> Either SemError a
 150 dc2 e (Right t) = Right t
 151 dc2 e (Left err) = Left err
 152
 153 extrPos :: Expr -> Pos
 154 extrPos (VarExpr p _) = p
 155 extrPos (Op2Expr p _ _ _) = p
 156 extrPos (Op1Expr p _ _) = p
 157 extrPos (IntExpr p _) = p
 158 extrPos (CharExpr p _) = p
 159 extrPos (BoolExpr p _) = p
 160 extrPos (FunExpr p _) = p
 161 extrPos (EmptyListExpr p) = p
 162 extrPos (TupleExpr p _) = p