From 3624c712d72d246f21d4e710cec7c11e052e0326 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Tue, 9 Dec 2025 16:32:32 +0100
Subject: Add the haskell book

---
 Haskell-book/09/src/EnumFromTo.purs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 Haskell-book/09/src/EnumFromTo.purs

(limited to 'Haskell-book/09/src/EnumFromTo.purs')

diff --git a/Haskell-book/09/src/EnumFromTo.purs b/Haskell-book/09/src/EnumFromTo.purs
new file mode 100644
index 0000000..f389c31
--- /dev/null
+++ b/Haskell-book/09/src/EnumFromTo.purs
@@ -0,0 +1,15 @@
+module EnumFromTo where
+
+import Data.Array ((:), reverse)
+import Data.Enum (class Enum, succ)
+import Data.Maybe (Maybe(..))
+import Prelude
+
+enumFromTo :: forall a. Enum a => a -> a -> Array a
+enumFromTo start end = reverse $ enumFromTo' [] (Just start)
+    where enumFromTo' :: Array a -> Maybe a -> Array a
+          enumFromTo' acc (Just start')
+              | start' > end  = acc
+              | start' == end = start' : acc
+              | otherwise     = enumFromTo' (start' : acc) (succ start')
+          enumFromTo' acc Nothing = acc
-- 
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