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/17/Constant.hs | 13 +++++++++++++ 1 file changed, 13 insertions(+) create mode 100644 Haskell-book/17/Constant.hs (limited to 'Haskell-book/17/Constant.hs') diff --git a/Haskell-book/17/Constant.hs b/Haskell-book/17/Constant.hs new file mode 100644 index 0000000..f25da54 --- /dev/null +++ b/Haskell-book/17/Constant.hs @@ -0,0 +1,13 @@ +module Constant where + +newtype Constant a b = + Constant { getConstant :: a } + deriving (Eq, Ord, Show) + +instance Functor (Constant a) where + fmap _ (Constant x) = Constant x + +instance Monoid a + => Applicative (Constant a) where + pure x = Constant mempty + (Constant x) <*> (Constant y) = Constant $ mappend x y -- cgit v1.2.3