module CC.AST.Typed(
    module CC.AST.Typed,
    module CC.Types
) where

import Data.List

import CC.Pretty
import CC.Types


data Program = Program [Def]
  deriving (Show, Read)

data Def = Def Name Expr
  deriving (Show, Read)

data Type = TFun Type Type
          | TInt
          | TTup [Type]
          | TyVar Int
  deriving (Show, Read)

data TypeScheme = TypeScheme [Int] Type
  deriving (Show, Read)

data Expr = Lam Type Occ Expr
          | Let Occ Expr Expr
          | Call Type Expr Expr
          | Int Int
          | Tup [Expr]
          | Var Occ
  deriving (Show, Read)

data Occ = Occ Name Type
  deriving (Show, Read)

exprType :: Expr -> Type
exprType (Lam typ _ _) = typ
exprType (Let _ _ body) = exprType body
exprType (Call typ _ _) = typ
exprType (Int _) = TInt
exprType (Tup es) = TTup (map exprType es)
exprType (Var (Occ _ typ)) = typ

instance Pretty Type where
    prettyPrec _ TInt = "Int"
    prettyPrec p (TFun a b) =
        precParens p 2 (prettyPrec 3 a ++ " -> " ++ prettyPrec 2 b)
    prettyPrec _ (TTup ts) =
        "(" ++ intercalate ", " (map pretty ts) ++ ")"
    prettyPrec _ (TyVar i) = 't' : show i

instance Pretty TypeScheme where
    prettyPrec p (TypeScheme bnds ty) =
        precParens p 2
            ("forall " ++ intercalate " " (map (pretty . TyVar) bnds) ++ ". " ++
                prettyPrec 2 ty)

instance Pretty Expr where
    prettyPrec p (Lam ty (Occ n t) e) =
        precParens p 2 $
            "(\\(" ++ n ++ " :: " ++ pretty t ++ ") -> "
                ++ prettyPrec 2 e ++ ") :: " ++ pretty ty
    prettyPrec p (Let (Occ n t) rhs e) =
        precParens p 2 $
            "let (" ++ n ++ " :: " ++ pretty t ++ ") = " ++ pretty rhs ++ " " ++
                (case e of
                   Let _ _ _ -> pretty e
                   _ -> "in " ++ pretty e)
    prettyPrec p (Call ty e1 e2) =
        precParens p 2 $
            prettyPrec 3 e1 ++ " " ++ prettyPrec 3 e2 ++ " :: " ++ pretty ty
    prettyPrec _ (Int i) = show i
    prettyPrec _ (Tup es) = "(" ++ intercalate ", " (map pretty es) ++ ")"
    prettyPrec p (Var (Occ n t)) =
        precParens p 2 $
            show n ++ " :: " ++ pretty t

instance Pretty Def where
    pretty (Def n e) = n ++ " = " ++ pretty e

instance Pretty Program where
    pretty (Program defs) = concatMap ((++ "\n") . pretty) defs