From 98329e0a3dd4f78b5d815ac3896272ec70904901 Mon Sep 17 00:00:00 2001 From: Eugen Wissner Date: Thu, 11 Dec 2025 10:28:11 +0100 Subject: Add remaining haskell book exercises --- Haskell-book/15/semigroup/src/Identity.hs | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) create mode 100644 Haskell-book/15/semigroup/src/Identity.hs (limited to 'Haskell-book/15/semigroup/src/Identity.hs') diff --git a/Haskell-book/15/semigroup/src/Identity.hs b/Haskell-book/15/semigroup/src/Identity.hs new file mode 100644 index 0000000..cb7180a --- /dev/null +++ b/Haskell-book/15/semigroup/src/Identity.hs @@ -0,0 +1,16 @@ +module Identity where + +import Data.Semigroup +import Test.QuickCheck + +newtype Identity a = Identity a deriving (Show, Eq) + +instance Semigroup a => Semigroup (Identity a) where + (Identity x) <> (Identity y) = Identity (x <> y) + +instance Monoid a => Monoid (Identity a) where + mempty = Identity mempty + mappend (Identity x) (Identity y) = Identity $ mappend x y + +instance Arbitrary a => Arbitrary (Identity a) where + arbitrary = fmap Identity arbitrary -- cgit v1.2.3