{-# OPTIONS_GHC -fglasgow-exts #-}

-- 
-- Copyright (C) 2005 Stefan Wehr - http://www.stefanwehr.de
--
-- This program is free software; you can redistribute it and/or
-- modify it under the terms of the GNU General Public License as
-- published by the Free Software Foundation; either version 2 of
-- the License, or (at your option) any later version.
-- 
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-- General Public License for more details.
-- 
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
-- 02111-1307, USA.
-- 

module Phrac.Kinds where

import Phrac.Symtab
import Phrac.AbstractSyntax
import Phrac.Error

class HasKind t where
    kindOf :: t -> ST Kind

instance HasKind TypeVarId where
    kindOf id = kindOfTypeVarId id

instance HasKind TypeId where
    kindOf id = 
        do td <- findTypeDef id
           kindOf td

instance HasKind AssocTypeId where
    kindOf id = 
        do tsig <- findAssocTypeSig id
           kindOf tsig

instance HasKind TypeDef where
    kindOf td = 
        do paramKinds <- mapM kindOf (tydef_params td)
           return $ kindFun paramKinds KindStar

instance HasKind AssocTypeSig where
    kindOf (AssocTypeSig id params _) =
        do paramKinds <- mapM kindOf params
           return $ kindFun paramKinds KindStar

instance HasKind Type where
    kindOf (TyVar id) = kindOf id
    kindOf (TyApp t _) = 
        do k <- kindOf t
           case k of
             KindFun _ k' -> return k'
             _ -> panic "illegal kind"
    kindOf (TyConstruct id) = kindOf id
    kindOf (TyAssoc at) = kindOf at

instance HasKind AssocType where
    kindOf at = 
        do k <- kindOf (assoc_name at)
           return $ erase k (assoc_params at)
        where erase k [] = k
              erase (KindFun _ k) (x:xs) = erase k xs
              erase _ _ = panic "illegal kind"