diff --git a/CHANGELOG.md b/CHANGELOG.md
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+++ b/CHANGELOG.md
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+# Revision history for tehepero
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+Copyright Fumiaki Kinoshita (c) 2020
+
+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 Fumiaki Kinoshita 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/Setup.hs b/Setup.hs
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--- /dev/null
+++ b/Setup.hs
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+import Distribution.Simple
+main = defaultMain
diff --git a/src/Control/Panic.hs b/src/Control/Panic.hs
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--- /dev/null
+++ b/src/Control/Panic.hs
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+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE OverloadedStrings #-}
+module Control.Panic
+  (Panic(..)
+  , PrettyEx(..)
+  , panic
+  , unwrap
+  , expect
+  , withPanic) where
+
+import Control.Monad.Catch
+import Data.Fallible
+import Data.Text.Prettyprint.Doc
+import Data.Text.Prettyprint.Doc.Render.Terminal
+import GHC.Stack
+import System.IO (stderr)
+import System.Exit (exitFailure)
+
+data Panic = Panic !CallStack !(Doc AnsiStyle)
+  deriving (Show)
+instance Exception Panic
+
+class PrettyEx a where
+  prettyEx :: a -> Doc AnsiStyle
+  prettyExList :: [a] -> Doc AnsiStyle
+  prettyExList = foldMap prettyEx
+
+instance (a ~ AnsiStyle) => PrettyEx (Doc a) where
+  prettyEx = id
+
+instance PrettyEx () where
+  prettyEx _ = "Nothing"
+
+instance PrettyEx Char where
+  prettyEx = pretty
+  prettyExList = pretty
+
+instance PrettyEx a => PrettyEx [a] where
+  prettyEx = annotate (color Cyan) . prettyExList
+
+instance PrettyEx CallStack where
+  prettyEx = vsep . map prettyCallSite . getCallStack where
+    prettyCallSite (f, loc) = annotate bold (pretty f) <> ", called at " <> prettyEx loc
+
+instance PrettyEx SrcLoc where
+  prettyEx SrcLoc {..} = mconcat
+      [ annotate (color Blue) (pretty srcLocFile), ":"
+      , pretty srcLocStartLine, ":"
+      , pretty srcLocStartCol, " in "
+      , annotate (color Yellow) $ pretty srcLocPackage, ":", pretty srcLocModule
+      ]
+
+instance PrettyEx Panic where
+  prettyEx (Panic stack doc) = vsep [annotate (color Red <> bold) "!!!Panic!!!", doc, prettyEx stack]
+
+-- | Throw an error with a pretty-printable message.
+panic :: (MonadThrow m, HasCallStack) => Doc AnsiStyle -> m a
+panic = throwM . Panic (popCallStack callStack)
+{-# INLINE panic #-}
+
+-- | Try to obtain the result of a 'Fallible' value. If 'panic's it fails.
+unwrap :: (Fallible f, PrettyEx (Failure f), MonadThrow m, HasCallStack)
+  => f a -> m a
+unwrap = either (panic . prettyEx) pure . tryFallible
+{-# INLINE unwrap #-}
+
+-- | Prepend a message if it fails to obtain the result.
+expect :: (Fallible f, PrettyEx (Failure f), MonadThrow m, HasCallStack)
+  => Doc AnsiStyle -> f a -> m a
+expect e = either (panic . (prefix<>) . prettyEx) pure . tryFallible where
+  prefix = e <> ": "
+{-# INLINE expect #-}
+
+-- | Add an exception handler for 'Panic' with prettifed output.
+withPanic :: IO a -> IO a
+withPanic m = m `catch` \e -> do
+  hPutDoc stderr $ prettyEx (e :: Panic) <> hardline
+  exitFailure
diff --git a/tehepero.cabal b/tehepero.cabal
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--- /dev/null
+++ b/tehepero.cabal
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+cabal-version:       2.4
+name:                tehepero
+version:             0
+synopsis:            Prettier error
+description:         Haskell port of Rust's unwrap and except
+bug-reports:         https://github.com/fumieval/tehepero
+license:             BSD-3-Clause
+license-file:        LICENSE
+author:              Fumiaki Kinoshita
+maintainer:          fumiexcel@gmail.com
+copyright:           Copyright (c) 2020- Fumiaki Kinoshita
+category:            Control
+extra-source-files:  CHANGELOG.md
+
+source-repository head
+  type:     git
+  location: https://github.com/fumieval/tehepero
+
+library
+  exposed-modules:     Control.Panic
+  -- other-modules:
+  -- other-extensions:
+  build-depends:       base >=4.12.0.0 && <4.15
+    , prettyprinter
+    , prettyprinter-ansi-terminal
+    , exceptions
+    , fallible
+  hs-source-dirs:      src
+  default-language:    Haskell2010