-- Haskel data types for the abstract syntax.
-- Generated by the BNF converter.

{-# LANGUAGE GeneralizedNewtypeDeriving #-}

-- | The abstract syntax of language Prolog.

module AbsProlog where

import qualified Prelude as T (String)
import qualified Prelude as C (Eq, Ord, Show, Read)

import Data.String

data Database
    = Db [Clause]
    -- ^ Database ::= Clause
  deriving (C.Eq, C.Ord, C.Show, C.Read)

data Clause
    = Directive [Predicate]
    -- ^ Clause ::= ":-" Predicate
    | Fact Predicate
    -- ^ Clause ::= Predicate
    | Rule Predicate [Predicate]
    -- ^ Clause ::= Predicate ":-" Predicate
  deriving (C.Eq, C.Ord, C.Show, C.Read)

data Predicate
    = APred Atom
    -- ^ Predicate ::= Atom
    | CPred Atom [Term]
    -- ^ Predicate ::= Atom "(" Term ")"
  deriving (C.Eq, C.Ord, C.Show, C.Read)

data Term
    = Complex Atom [Term]
    -- ^ Term ::= Atom "(" Term ")"
    | TAtom Atom
    -- ^ Term ::= Atom
    | TList List
    -- ^ Term ::= List
    | VarT Var
    -- ^ Term ::= Var
  deriving (C.Eq, C.Ord, C.Show, C.Read)

data Atom
    = Atm LIdent
    -- ^ Atom ::= LIdent
    | EAtm Ident
    -- ^ Atom ::= "\'" Ident "\'"
  deriving (C.Eq, C.Ord, C.Show, C.Read)

data Var
    = A Wild
    -- ^ Var ::= Wild
    | V UIdent
    -- ^ Var ::= UIdent
  deriving (C.Eq, C.Ord, C.Show, C.Read)

data List
    = Cons [Term] List
    -- ^ List ::= "[" Term "|" List "]"
    | ConsV [Term] Var
    -- ^ List ::= "[" Term "|" Var "]"
    | Empty
    -- ^ List ::= "[" "]"
    | Enum [Term]
    -- ^ List ::= "[" Term "]"
  deriving (C.Eq, C.Ord, C.Show, C.Read)

newtype Ident
    = Ident T.String
  deriving (C.Eq, C.Ord, C.Show, C.Read, Data.String.IsString)

newtype UIdent
    = UIdent T.String
  deriving (C.Eq, C.Ord, C.Show, C.Read, Data.String.IsString)

newtype LIdent
    = LIdent T.String
  deriving (C.Eq, C.Ord, C.Show, C.Read, Data.String.IsString)

newtype Wild
    = Wild T.String
  deriving (C.Eq, C.Ord, C.Show, C.Read, Data.String.IsString)