diff --git a/ChangeLog.md b/ChangeLog.md
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--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,3 @@
+# Changelog for union-angle
+
+## Unreleased changes
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+Copyright Author name here (c) 2021
+
+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
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--- /dev/null
+++ b/README.md
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+# union-angle
+
+Union type that include radian angle and degree angle.
+
+```
+> a = Radian pi
+> a
+Radian 3.141592653589793
+> degree a
+180.0
+> Degree d = a
+> d
+180.0
+> Degree 180
+Degree 180
+> it + Radian pi
+Radian 6.283185307179586
+```
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/Data/Angle.hs b/src/Data/Angle.hs
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--- /dev/null
+++ b/src/Data/Angle.hs
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+{-# LANGUAGE BlockArguments, LambdaCase #-}
+{-# LANGUAGE PatternSynonyms, ViewPatterns #-}
+{-# OPTIONS_GHC -Wall -fno-warn-tabs #-}
+
+module Data.Angle (Angle, pattern Radian, radian, pattern Degree, degree) where
+
+import Control.Arrow (second)
+import Text.Read (Lexeme(..), readPrec, step, parens, prec, lexP, (+++))
+
+---------------------------------------------------------------------------
+
+-- * DATA TYPE AND PATTERN
+-- * INSTANCE DEFINITION
+
+---------------------------------------------------------------------------
+-- DATA TYPE AND PATTERN
+---------------------------------------------------------------------------
+
+data Angle f = Radian_ f | Degree_ f
+
+-- ^ >>> Radian pi
+-- Radian 3.141592653589793
+-- >>> degree it
+-- 180.0
+--
+-- >>> Degree 180
+-- Degree 180.0
+--
+-- >>> Radian pi + Degree 180
+-- Radian 6.283185307179586
+
+{-# COMPLETE Radian #-}
+
+pattern Radian :: Floating f => f -> Angle f
+pattern Radian r <- (radian -> r) where Radian = Radian_
+
+radian :: Floating f => Angle f -> f
+radian = \case Radian_ r -> r; Degree_ d -> d * pi / 180
+
+{-# COMPLETE Degree #-}
+
+pattern Degree :: Floating f => f -> Angle f
+pattern Degree d <- (degree -> d) where Degree = Degree_
+
+degree :: Floating f => Angle f -> f
+degree = \case Radian_ r -> r * 180 / pi; Degree_ d -> d
+
+---------------------------------------------------------------------------
+-- INSTANCE DEFINITION
+---------------------------------------------------------------------------
+
+instance Show f => Show (Angle f) where
+	showsPrec d = \case
+		Radian_ x -> showParen (d > 10)
+			$ ("Radian " ++) . showsPrec 11 x
+		Degree_ x -> showParen (d > 10)
+			$ ("Degree " ++) . showsPrec 11 x
+
+instance (Read f, Floating f) => Read (Angle f) where
+	readPrec = parens $
+		prec 10 do Ident "Radian" <- lexP; Radian_ <$> step readPrec
+		+++
+		prec 10 do Ident "Degree" <- lexP; Degree_ <$> step readPrec
+
+instance (Eq f, Floating f) => Eq (Angle f) where
+	Degree_ x == Degree_ y = x == y; Radian x == Radian y = x == y
+
+instance (Ord f, Floating f) => Ord (Angle f) where
+	Degree_ x <= Degree_ y = x <= y; Radian x <= Radian y = x <= y
+
+instance Floating f => Num (Angle f) where
+	Degree_ x + Degree_ y = Degree_ $ x + y
+	Radian x + Radian y = Radian_ $ x + y
+	Degree_ x * Degree_ y = Degree_ $ x * y * pi / 180
+	Radian x * Radian y = Radian_ $ x * y
+	negate = \case Radian_ x -> Radian_ $ - x; Degree_ x -> Degree_ $ - x
+	abs = \case Radian_ x -> Radian_ $ abs x; Degree_ x -> Degree_ $ abs x
+	signum = \case
+		Radian_ x -> Radian_ $ signum x; Degree_ x -> Radian_ $ signum x
+	fromInteger = Radian_ . fromInteger
+
+instance Floating f => Fractional (Angle f) where
+	recip = \case
+		Radian_ x -> Radian_ $ recip x
+		Degree_ x -> Degree_ $ recip x * (180 / pi) ^ (2 :: Int)
+	fromRational = Radian_ . fromRational
+
+instance (Floating f, Real f) => Real (Angle f) where
+	toRational = toRational . radian
+
+instance Floating f => Floating (Angle f) where
+	pi = Radian_ pi
+	exp = applyAngle exp
+	log = applyAngle log
+	sin = applyAngle sin
+	cos = applyAngle cos
+	asin = applyAngle asin
+	acos = applyAngle acos
+	atan = applyAngle atan
+	sinh = applyAngle sinh
+	cosh = applyAngle cosh
+	asinh = applyAngle asinh
+	acosh = applyAngle acosh
+	atanh = applyAngle atanh
+
+applyAngle :: Floating f => (f -> f) -> Angle f -> Angle f
+applyAngle f = \case
+	Radian_ x -> Radian_ $ f x
+	Degree_ x -> Degree_ $ f (x * pi / 180) * 180 / pi
+
+instance (Floating f, RealFrac f) => RealFrac (Angle f) where
+	properFraction = \case
+		Radian_ x -> Radian `second` properFraction x
+		Degree_ x -> (Degree_ . (/ pi) . (* 180))
+			`second` properFraction (x * pi / 180)
diff --git a/test/Spec.hs b/test/Spec.hs
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--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,2 @@
+main :: IO ()
+main = putStrLn "Test suite not yet implemented"
diff --git a/union-angle.cabal b/union-angle.cabal
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--- /dev/null
+++ b/union-angle.cabal
@@ -0,0 +1,50 @@
+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.34.4.
+--
+-- see: https://github.com/sol/hpack
+
+name:           union-angle
+version:        0.1.0.0
+synopsis:       Union type that include radian angle and degree angle
+description:    Please see the README on GitHub at <https://github.com/githubuser/union-angle#readme>
+category:       Data
+homepage:       https://github.com/githubuser/union-angle#readme
+bug-reports:    https://github.com/githubuser/union-angle/issues
+author:         Yoshikuni Jujo
+maintainer:     yoshikuni.jujo.pc@gmail.com
+copyright:      2021 Yoshikuni Jujo
+license:        BSD3
+license-file:   LICENSE
+build-type:     Simple
+extra-source-files:
+    README.md
+    ChangeLog.md
+
+source-repository head
+  type: git
+  location: https://github.com/githubuser/union-angle
+
+library
+  exposed-modules:
+      Data.Angle
+  other-modules:
+      Paths_union_angle
+  hs-source-dirs:
+      src
+  build-depends:
+      base >=4.7 && <5
+  default-language: Haskell2010
+
+test-suite union-angle-test
+  type: exitcode-stdio-1.0
+  main-is: Spec.hs
+  other-modules:
+      Paths_union_angle
+  hs-source-dirs:
+      test
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      base >=4.7 && <5
+    , union-angle
+  default-language: Haskell2010