{-

Verify output of cunningham-cards.pl

Copyright 2017 Ken Takusagawa

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 3 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, see <http://www.gnu.org/licenses/>.
-}

{-# LANGUAGE ScopedTypeVariables, LambdaCase #-}

module Main where {
import System.Environment(getArgs);
import Control.Exception(assert);
import Debug.Trace(trace);
import Data.Function((&));
import Control.Category((>>>));
import Prelude hiding((.),(>>));
--import System.IO(hSetBuffering,stdout,BufferMode(LineBuffering));
--import Data.List;
--import Control.Monad;
--import Data.Maybe;
--import qualified Data.Map as Map;
--import Data.Map(Map);
--import qualified Data.Set as Set;
--import Data.Set(Set);

-- to avoid the redundancy warning
trace_placeholder :: ();
trace_placeholder = (trace,assert) & (id >>> error) "trace_placeholder";

main :: IO();
main = getArgs >>= \case{
         ["go"]->go;
_ -> undefined;
};

go :: IO();
go = do {
getContents >>= (lines >>> map words >>> mapM_ check_line);
};

check_line :: [String] -> IO ();
check_line = \case {
('#':_):_ -> return ();
[_b,"bit",d,"divides","2","^",n,sign,"1"] -> if (mod (2 ^ ((read n)::Integer) & alter_by sign) (read d))==0
then return ();
else error n;
x -> error (show x);
};

alter_by :: String -> Integer -> Integer;
alter_by "+" = succ;
alter_by "-" = pred;
alter_by s = error $ "not plus or minus: " ++ s;
} --end