commit b45e0a3717632f7cfab0e2ef983f87dd77e74abf
Author: ryuga4 <ryuga4@o2.pl>
Date:   Fri May 3 17:23:30 2019 +0200

    init

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..113031c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.stack-work/
+parser-sandbox.cabal
+*~
\ No newline at end of file
diff --git a/ChangeLog.md b/ChangeLog.md
new file mode 100644
index 0000000..4f4f0c7
--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,3 @@
+# Changelog for parser-sandbox
+
+## Unreleased changes
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..102126f
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright Author name here (c) 2019
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Author name here nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..f9d8890
--- /dev/null
+++ b/README.md
@@ -0,0 +1 @@
+# parser-sandbox
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
index 0000000..9a994af
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/app/Main.hs b/app/Main.hs
new file mode 100644
index 0000000..9a696da
--- /dev/null
+++ b/app/Main.hs
@@ -0,0 +1,6 @@
+module Main where
+
+import Lib
+
+main :: IO ()
+main = go 
diff --git a/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/build/autogen/Paths_parser_sandbox.hs b/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/build/autogen/Paths_parser_sandbox.hs
new file mode 100644
index 0000000..b47563d
--- /dev/null
+++ b/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/build/autogen/Paths_parser_sandbox.hs
@@ -0,0 +1,50 @@
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE NoRebindableSyntax #-}
+{-# OPTIONS_GHC -fno-warn-missing-import-lists #-}
+module Paths_parser_sandbox (
+    version,
+    getBinDir, getLibDir, getDynLibDir, getDataDir, getLibexecDir,
+    getDataFileName, getSysconfDir
+  ) where
+
+import qualified Control.Exception as Exception
+import Data.Version (Version(..))
+import System.Environment (getEnv)
+import Prelude
+
+#if defined(VERSION_base)
+
+#if MIN_VERSION_base(4,0,0)
+catchIO :: IO a -> (Exception.IOException -> IO a) -> IO a
+#else
+catchIO :: IO a -> (Exception.Exception -> IO a) -> IO a
+#endif
+
+#else
+catchIO :: IO a -> (Exception.IOException -> IO a) -> IO a
+#endif
+catchIO = Exception.catch
+
+version :: Version
+version = Version [0,1,0,0] []
+bindir, libdir, dynlibdir, datadir, libexecdir, sysconfdir :: FilePath
+
+bindir     = "/home/me/.cabal/bin"
+libdir     = "/home/me/.cabal/lib/x86_64-linux-ghc-8.0.2/parser-sandbox-0.1.0.0-inplace"
+dynlibdir  = "/home/me/.cabal/lib/x86_64-linux-ghc-8.0.2"
+datadir    = "/home/me/.cabal/share/x86_64-linux-ghc-8.0.2/parser-sandbox-0.1.0.0"
+libexecdir = "/home/me/.cabal/libexec/x86_64-linux-ghc-8.0.2/parser-sandbox-0.1.0.0"
+sysconfdir = "/home/me/.cabal/etc"
+
+getBinDir, getLibDir, getDynLibDir, getDataDir, getLibexecDir, getSysconfDir :: IO FilePath
+getBinDir = catchIO (getEnv "parser_sandbox_bindir") (\_ -> return bindir)
+getLibDir = catchIO (getEnv "parser_sandbox_libdir") (\_ -> return libdir)
+getDynLibDir = catchIO (getEnv "parser_sandbox_dynlibdir") (\_ -> return dynlibdir)
+getDataDir = catchIO (getEnv "parser_sandbox_datadir") (\_ -> return datadir)
+getLibexecDir = catchIO (getEnv "parser_sandbox_libexecdir") (\_ -> return libexecdir)
+getSysconfDir = catchIO (getEnv "parser_sandbox_sysconfdir") (\_ -> return sysconfdir)
+
+getDataFileName :: FilePath -> IO FilePath
+getDataFileName name = do
+  dir <- getDataDir
+  return (dir ++ "/" ++ name)
diff --git a/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/build/autogen/cabal_macros.h b/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/build/autogen/cabal_macros.h
new file mode 100644
index 0000000..7251af3
--- /dev/null
+++ b/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/build/autogen/cabal_macros.h
@@ -0,0 +1,154 @@
+/* DO NOT EDIT: This file is automatically generated by Cabal */
+
+/* package parser-sandbox-0.1.0.0 */
+#ifndef VERSION_parser_sandbox
+#define VERSION_parser_sandbox "0.1.0.0"
+#endif /* VERSION_parser_sandbox */
+#ifndef MIN_VERSION_parser_sandbox
+#define MIN_VERSION_parser_sandbox(major1,major2,minor) (\
+  (major1) <  0 || \
+  (major1) == 0 && (major2) <  1 || \
+  (major1) == 0 && (major2) == 1 && (minor) <= 0)
+#endif /* MIN_VERSION_parser_sandbox */
+
+/* package base-4.9.1.0 */
+#ifndef VERSION_base
+#define VERSION_base "4.9.1.0"
+#endif /* VERSION_base */
+#ifndef MIN_VERSION_base
+#define MIN_VERSION_base(major1,major2,minor) (\
+  (major1) <  4 || \
+  (major1) == 4 && (major2) <  9 || \
+  (major1) == 4 && (major2) == 9 && (minor) <= 1)
+#endif /* MIN_VERSION_base */
+
+/* tool cpphs-1.20.8 */
+#ifndef TOOL_VERSION_cpphs
+#define TOOL_VERSION_cpphs "1.20.8"
+#endif /* TOOL_VERSION_cpphs */
+#ifndef MIN_TOOL_VERSION_cpphs
+#define MIN_TOOL_VERSION_cpphs(major1,major2,minor) (\
+  (major1) <  1 || \
+  (major1) == 1 && (major2) <  20 || \
+  (major1) == 1 && (major2) == 20 && (minor) <= 8)
+#endif /* MIN_TOOL_VERSION_cpphs */
+
+/* tool gcc-7 */
+#ifndef TOOL_VERSION_gcc
+#define TOOL_VERSION_gcc "7"
+#endif /* TOOL_VERSION_gcc */
+#ifndef MIN_TOOL_VERSION_gcc
+#define MIN_TOOL_VERSION_gcc(major1,major2,minor) (\
+  (major1) <  7 || \
+  (major1) == 7 && (major2) <  0 || \
+  (major1) == 7 && (major2) == 0 && (minor) <= 0)
+#endif /* MIN_TOOL_VERSION_gcc */
+
+/* tool ghc-8.0.2 */
+#ifndef TOOL_VERSION_ghc
+#define TOOL_VERSION_ghc "8.0.2"
+#endif /* TOOL_VERSION_ghc */
+#ifndef MIN_TOOL_VERSION_ghc
+#define MIN_TOOL_VERSION_ghc(major1,major2,minor) (\
+  (major1) <  8 || \
+  (major1) == 8 && (major2) <  0 || \
+  (major1) == 8 && (major2) == 0 && (minor) <= 2)
+#endif /* MIN_TOOL_VERSION_ghc */
+
+/* tool ghc-pkg-8.0.2 */
+#ifndef TOOL_VERSION_ghc_pkg
+#define TOOL_VERSION_ghc_pkg "8.0.2"
+#endif /* TOOL_VERSION_ghc_pkg */
+#ifndef MIN_TOOL_VERSION_ghc_pkg
+#define MIN_TOOL_VERSION_ghc_pkg(major1,major2,minor) (\
+  (major1) <  8 || \
+  (major1) == 8 && (major2) <  0 || \
+  (major1) == 8 && (major2) == 0 && (minor) <= 2)
+#endif /* MIN_TOOL_VERSION_ghc_pkg */
+
+/* tool haddock-2.17.3 */
+#ifndef TOOL_VERSION_haddock
+#define TOOL_VERSION_haddock "2.17.3"
+#endif /* TOOL_VERSION_haddock */
+#ifndef MIN_TOOL_VERSION_haddock
+#define MIN_TOOL_VERSION_haddock(major1,major2,minor) (\
+  (major1) <  2 || \
+  (major1) == 2 && (major2) <  17 || \
+  (major1) == 2 && (major2) == 17 && (minor) <= 3)
+#endif /* MIN_TOOL_VERSION_haddock */
+
+/* tool hpc-0.67 */
+#ifndef TOOL_VERSION_hpc
+#define TOOL_VERSION_hpc "0.67"
+#endif /* TOOL_VERSION_hpc */
+#ifndef MIN_TOOL_VERSION_hpc
+#define MIN_TOOL_VERSION_hpc(major1,major2,minor) (\
+  (major1) <  0 || \
+  (major1) == 0 && (major2) <  67 || \
+  (major1) == 0 && (major2) == 67 && (minor) <= 0)
+#endif /* MIN_TOOL_VERSION_hpc */
+
+/* tool hsc2hs-0.68.1 */
+#ifndef TOOL_VERSION_hsc2hs
+#define TOOL_VERSION_hsc2hs "0.68.1"
+#endif /* TOOL_VERSION_hsc2hs */
+#ifndef MIN_TOOL_VERSION_hsc2hs
+#define MIN_TOOL_VERSION_hsc2hs(major1,major2,minor) (\
+  (major1) <  0 || \
+  (major1) == 0 && (major2) <  68 || \
+  (major1) == 0 && (major2) == 68 && (minor) <= 1)
+#endif /* MIN_TOOL_VERSION_hsc2hs */
+
+/* tool hscolour-1.24 */
+#ifndef TOOL_VERSION_hscolour
+#define TOOL_VERSION_hscolour "1.24"
+#endif /* TOOL_VERSION_hscolour */
+#ifndef MIN_TOOL_VERSION_hscolour
+#define MIN_TOOL_VERSION_hscolour(major1,major2,minor) (\
+  (major1) <  1 || \
+  (major1) == 1 && (major2) <  24 || \
+  (major1) == 1 && (major2) == 24 && (minor) <= 0)
+#endif /* MIN_TOOL_VERSION_hscolour */
+
+/* tool pkg-config-0.29.1 */
+#ifndef TOOL_VERSION_pkg_config
+#define TOOL_VERSION_pkg_config "0.29.1"
+#endif /* TOOL_VERSION_pkg_config */
+#ifndef MIN_TOOL_VERSION_pkg_config
+#define MIN_TOOL_VERSION_pkg_config(major1,major2,minor) (\
+  (major1) <  0 || \
+  (major1) == 0 && (major2) <  29 || \
+  (major1) == 0 && (major2) == 29 && (minor) <= 1)
+#endif /* MIN_TOOL_VERSION_pkg_config */
+
+/* tool runghc-8.0.2 */
+#ifndef TOOL_VERSION_runghc
+#define TOOL_VERSION_runghc "8.0.2"
+#endif /* TOOL_VERSION_runghc */
+#ifndef MIN_TOOL_VERSION_runghc
+#define MIN_TOOL_VERSION_runghc(major1,major2,minor) (\
+  (major1) <  8 || \
+  (major1) == 8 && (major2) <  0 || \
+  (major1) == 8 && (major2) == 0 && (minor) <= 2)
+#endif /* MIN_TOOL_VERSION_runghc */
+
+/* tool strip-2.30 */
+#ifndef TOOL_VERSION_strip
+#define TOOL_VERSION_strip "2.30"
+#endif /* TOOL_VERSION_strip */
+#ifndef MIN_TOOL_VERSION_strip
+#define MIN_TOOL_VERSION_strip(major1,major2,minor) (\
+  (major1) <  2 || \
+  (major1) == 2 && (major2) <  30 || \
+  (major1) == 2 && (major2) == 30 && (minor) <= 0)
+#endif /* MIN_TOOL_VERSION_strip */
+
+#ifndef CURRENT_PACKAGE_KEY
+#define CURRENT_PACKAGE_KEY "parser-sandbox-0.1.0.0-inplace"
+#endif /* CURRENT_PACKAGE_KEY */
+#ifndef CURRENT_COMPONENT_ID
+#define CURRENT_COMPONENT_ID "parser-sandbox-0.1.0.0-inplace"
+#endif /* CURRENT_COMPONENT_ID */
+#ifndef CURRENT_PACKAGE_VERSION
+#define CURRENT_PACKAGE_VERSION "0.1.0.0"
+#endif /* CURRENT_PACKAGE_VERSION */
diff --git a/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/cache/config b/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/cache/config
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diff --git a/dist-newstyle/cache/plan.json b/dist-newstyle/cache/plan.json
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+++ b/dist-newstyle/cache/plan.json
@@ -0,0 +1 @@
+{"cabal-version":"2.4.1.0","cabal-lib-version":"2.4.1.0","compiler-id":"ghc-8.0.2","os":"linux","arch":"x86_64","install-plan":[{"type":"pre-existing","id":"base-4.9.1.0","pkg-name":"base","pkg-version":"4.9.1.0","depends":["ghc-prim-0.5.0.0","integer-gmp-1.0.0.1","rts"]},{"type":"pre-existing","id":"ghc-prim-0.5.0.0","pkg-name":"ghc-prim","pkg-version":"0.5.0.0","depends":["rts"]},{"type":"pre-existing","id":"integer-gmp-1.0.0.1","pkg-name":"integer-gmp","pkg-version":"1.0.0.1","depends":["ghc-prim-0.5.0.0"]},{"type":"configured","id":"parser-sandbox-0.1.0.0-inplace","pkg-name":"parser-sandbox","pkg-version":"0.1.0.0","flags":{},"style":"local","pkg-src":{"type":"local","path":"/home/me/Projekty/Haskell/parser-sandbox/."},"dist-dir":"/home/me/Projekty/Haskell/parser-sandbox/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0","depends":["base-4.9.1.0"],"exe-depends":[],"component-name":"lib"},{"type":"configured","id":"parser-sandbox-0.1.0.0-inplace-parser-sandbox-exe","pkg-name":"parser-sandbox","pkg-version":"0.1.0.0","flags":{},"style":"local","pkg-src":{"type":"local","path":"/home/me/Projekty/Haskell/parser-sandbox/."},"dist-dir":"/home/me/Projekty/Haskell/parser-sandbox/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/x/parser-sandbox-exe","depends":["base-4.9.1.0","parser-sandbox-0.1.0.0-inplace"],"exe-depends":[],"component-name":"exe:parser-sandbox-exe","bin-file":"/home/me/Projekty/Haskell/parser-sandbox/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/x/parser-sandbox-exe/build/parser-sandbox-exe/parser-sandbox-exe"},{"type":"configured","id":"parser-sandbox-0.1.0.0-inplace-parser-sandbox-test","pkg-name":"parser-sandbox","pkg-version":"0.1.0.0","flags":{},"style":"local","pkg-src":{"type":"local","path":"/home/me/Projekty/Haskell/parser-sandbox/."},"dist-dir":"/home/me/Projekty/Haskell/parser-sandbox/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/t/parser-sandbox-test","depends":["base-4.9.1.0","parser-sandbox-0.1.0.0-inplace"],"exe-depends":[],"component-name":"test:parser-sandbox-test","bin-file":"/home/me/Projekty/Haskell/parser-sandbox/dist-newstyle/build/x86_64-linux/ghc-8.0.2/parser-sandbox-0.1.0.0/t/parser-sandbox-test/build/parser-sandbox-test/parser-sandbox-test"},{"type":"pre-existing","id":"rts","pkg-name":"rts","pkg-version":"1.0","depends":[]}]}
\ No newline at end of file
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diff --git a/package.yaml b/package.yaml
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+++ b/package.yaml
@@ -0,0 +1,49 @@
+name:                parser-sandbox
+version:             0.1.0.0
+github:              "githubuser/parser-sandbox"
+license:             BSD3
+author:              "Author name here"
+maintainer:          "example@example.com"
+copyright:           "2019 Author name here"
+
+extra-source-files:
+- README.md
+- ChangeLog.md
+
+# Metadata used when publishing your package
+# synopsis:            Short description of your package
+# category:            Web
+
+# To avoid duplicated efforts in documentation and dealing with the
+# complications of embedding Haddock markup inside cabal files, it is
+# common to point users to the README.md file.
+description:         Please see the README on GitHub at <https://github.com/githubuser/parser-sandbox#readme>
+
+dependencies:
+- base >= 4.7 && < 5
+- transformers
+
+library:
+  source-dirs: src
+
+executables:
+  parser-sandbox-exe:
+    main:                Main.hs
+    source-dirs:         app
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - parser-sandbox
+
+tests:
+  parser-sandbox-test:
+    main:                Spec.hs
+    source-dirs:         test
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - parser-sandbox
diff --git a/src/Lib.hs b/src/Lib.hs
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+++ b/src/Lib.hs
@@ -0,0 +1,221 @@
+{-# OPTIONS_GHC -fno-warn-unused-do-bind #-}
+{-# LANGUAGE TypeOperators #-}
+
+module Lib where
+
+import Data.Char
+import Control.Monad
+import Control.Applicative
+import Control.Monad.Trans.State
+import Control.Monad.Trans.Class
+
+
+newtype Parser a = Parser { parse :: String -> [(a,String)]}
+
+
+
+
+
+runParser :: Parser a -> String -> a
+runParser m s =
+  case parse m s of
+    [(res,[])] -> res
+    [(_,rs)] -> error "Parser did not consume entire stream"
+    _ -> error "Parser error"
+
+
+
+item :: Parser Char
+item = Parser $ \s ->
+  case s of
+    [] -> []
+    (c:cs) -> [(c,cs)]
+
+
+bind :: Parser a -> (a -> Parser b) -> Parser b
+bind p f = Parser $ \s ->
+  do
+    (a1,s1) <- parse p s
+    parse (f a1) s1
+
+unit :: a -> Parser a
+unit a = Parser (\s -> [(a,s)])
+
+
+instance Functor Parser where
+  fmap f (Parser cs) = Parser $ \s -> [(f a, b) | (a,b) <- cs s]
+
+instance Applicative Parser where
+  pure = return
+  (Parser cs1) <*> (Parser cs2) = Parser (\s -> [(f a, s2) | (f, s1) <- cs1 s, (a, s2) <- cs2 s1])
+
+instance Monad Parser where
+  return = unit
+  (>>=) = bind
+
+instance MonadPlus Parser where
+  mzero = failure
+  mplus = combine
+
+instance Alternative Parser where
+  empty = mzero
+  (<|>) = option
+
+failure :: Parser a
+failure = Parser $ \cs -> []
+
+combine :: Parser a -> Parser a -> Parser a
+combine p q = Parser $ \s -> parse p s <> parse q s
+
+
+option :: Parser a -> Parser a -> Parser a
+option p q = Parser $ \s ->
+  case parse p s of
+    [] -> parse q s
+    res -> res
+
+satisfy :: (Char -> Bool) -> Parser Char
+satisfy p =
+  item >>= \c ->
+             if p c
+             then unit c
+             else (Parser (\cs -> []))
+
+
+oneOf :: [Char] -> Parser Char
+oneOf s = satisfy (flip elem s)
+
+chainl :: Parser a -> Parser (a -> a -> a) -> a -> Parser a
+chainl p op a = (p `chainl1` op) <|> return a
+
+chainl1 :: Parser a -> Parser (a -> a -> a) -> Parser a
+chainl1 p op = do { a <- p; rest a}
+  where rest a = (do
+                     f <- op
+                     b <- p
+                     rest (f a b)) <|> return a
+
+
+
+
+char :: Char -> Parser Char
+char c = satisfy (c ==)
+
+natural :: Parser Integer
+natural = read <$> some (satisfy isDigit)
+
+
+string :: String -> Parser String
+string [] = return []
+string (c:cs) = do
+  char c
+  string cs
+  return (c:cs)
+
+token :: Parser a -> Parser a
+token p = do
+  a <- p
+  spaces
+  return a
+
+reserved :: String -> Parser String
+reserved s = token (string s)
+
+spaces :: Parser String
+spaces = many $ oneOf " \n\r"
+
+
+digit :: Parser Char
+digit = satisfy isDigit
+
+number :: Parser Int
+number = do
+  s <- string "-" <|> return []
+  cs <- some digit
+  return $ read $ s ++ cs
+
+parens :: Parser a -> Parser a
+parens m = do
+  reserved "("
+  n <- token m
+  reserved ")"
+  return n
+
+
+data Sentence = T
+              | F
+              | V Char
+              | N Sentence
+              | Sentence `SOR` Sentence
+              | Sentence `SAND` Sentence
+              | Sentence `SEQ` Sentence
+              | Sentence `SIMP` Sentence
+              deriving (Eq)
+
+
+instance Show Sentence where
+  show T = "T"
+  show F = "F"
+  show (V c) = [c]
+  show (N s) = "~"++show s
+  show (SOR a b) = "(" ++ show a ++ " v " ++ show b ++ ")"
+  show (SAND a b) = "(" ++ show a ++ " ^ " ++ show b ++ ")"
+  show (SEQ a b) = "(" ++ show a ++ " == " ++ show b ++ ")"
+  show (SIMP a b) = "(" ++ show a ++ " => " ++ show b ++ ")"
+
+sentence :: Parser Sentence
+sentence = all <|> parens sentence
+  where
+    all = t <|> f <|> v <|> neg <|> or <|> and <|> eq <|> imp
+    t = do
+      char 'T'
+      return T
+    f = do
+      char 'F'
+      return F
+    v = do
+      i <- oneOf ['a'..'z']
+      return $ V i
+    orOP = reserved "v" >> return SOR
+    andOP = reserved "^" >> return SOR
+    eqOP = reserved "==" >> return SEQ
+    binary op = chainl1 (token $ parens sentence) op
+    or = binary orOP
+    and = binary andOP
+    eq = binary eqOP
+    imp = do
+      s1 <- token $ parens sentence
+      reserved "=>"
+      s2 <- token $ parens sentence
+      return $ SIMP s1 s2
+    neg = do
+      char '~'
+      s1 <- sentence
+      return $ N s1
+
+
+tautology :: Sentence -> StateT [(Char,Bool)] [] Bool
+tautology T = return True
+tautology F = return False
+tautology (N s) = not <$> tautology s
+tautology (V v) = do
+  store <- get
+  case lookup v store of
+    Nothing -> do
+      x <- lift [True,False]
+      modify $ ((v,x):)
+      return x
+    Just x ->
+      return x
+tautology (SOR a b) = liftM2 (||) (tautology a) (tautology b)
+tautology (SAND a b) = liftM2 (&&) (tautology a) (tautology b)
+tautology (SEQ a b) = liftM2 (==) (tautology a) (tautology b)
+tautology (SIMP a b) = liftM2 (||) (not <$> tautology a) (tautology b)
+checkTautology s = all ((== True) . fst) $ runStateT (tautology s) []
+
+go = do
+  s <- getLine
+  let s' = runParser sentence s
+  print s'
+  print $ checkTautology s'
+
diff --git a/stack.yaml b/stack.yaml
new file mode 100644
index 0000000..d0a6794
--- /dev/null
+++ b/stack.yaml
@@ -0,0 +1,64 @@
+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# https://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+#
+# The location of a snapshot can be provided as a file or url. Stack assumes
+# a snapshot provided as a file might change, whereas a url resource does not.
+#
+# resolver: ./custom-snapshot.yaml
+# resolver: https://example.com/snapshots/2018-01-01.yaml
+resolver: lts-13.19
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+# - location:
+#    git: https://github.com/commercialhaskell/stack.git
+#    commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+# - location: https://github.com/commercialhaskell/stack/commit/e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#  subdirs:
+#  - auto-update
+#  - wai
+packages:
+- .
+# Dependency packages to be pulled from upstream that are not in the resolver
+# using the same syntax as the packages field.
+# (e.g., acme-missiles-0.3)
+# extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+# flags: {}
+
+# Extra package databases containing global packages
+# extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=1.9"
+#
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor
diff --git a/test/Spec.hs b/test/Spec.hs
new file mode 100644
index 0000000..cd4753f
--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,2 @@
+main :: IO ()
+main = putStrLn "Test suite not yet implemented"