From 98329e0a3dd4f78b5d815ac3896272ec70904901 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Thu, 11 Dec 2025 10:28:11 +0100
Subject: Add remaining haskell book exercises

---
 Haskell-book/24/LearnParsers/src/LearnParsers.hs | 45 ++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 Haskell-book/24/LearnParsers/src/LearnParsers.hs

(limited to 'Haskell-book/24/LearnParsers/src/LearnParsers.hs')

diff --git a/Haskell-book/24/LearnParsers/src/LearnParsers.hs b/Haskell-book/24/LearnParsers/src/LearnParsers.hs
new file mode 100644
index 0000000..9c349fd
--- /dev/null
+++ b/Haskell-book/24/LearnParsers/src/LearnParsers.hs
@@ -0,0 +1,45 @@
+module LearnParsers where
+
+import Text.Trifecta
+
+stop :: Parser a
+stop = unexpected "stop"
+
+-- read a single character '1'
+one = char '1'
+
+-- read a single character '1', then die
+one' = one >> stop
+-- equivalent to char '1' >> stop
+
+-- read two characters, '1', and '2'
+oneTwo = char '1' >> char '2'
+
+-- read two characters,
+-- '1' and '2', then die
+
+oneTwo' = oneTwo >> stop
+
+testParse :: Parser Char -> IO ()
+testParse p = print $ parseString p mempty "123"
+
+pNL s = putStrLn ('\n' : s)
+
+oneTwoThree :: Parser String
+oneTwoThree = choice
+            [ string "123"
+            , string "12"
+            , string "1"
+            ]
+
+oneTwoThree' = oneTwoThree >> stop
+
+testParse' :: Parser String -> IO ()
+testParse' p = print $ parseString p mempty "123"
+
+oneTwoThree'' :: Parser Char
+oneTwoThree'' = choice
+        [ one
+        , oneTwo
+        , char '1' >> char '2' >> char '3'
+        ]
-- 
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