Working version with README

README.md

@@ -0,0 +1,206 @@
+# xmasTwelve
+
+A Christmas challenge: write a program to generate the lyrics to The Twelve
+Days of Christmas.
+
+This is the most stupidly Haskell way I could think of: it makes a product of
+all the combinations of "$NUMBER $WORD $WORD" and then filters them. Filtering
+on word length alone wasn't enough, so the signature for each gift also includes
+the offset into the following lists:
+
+```
+two turtle doves
+two turtle birds
+two turtle rings
+two French doves
+two French birds
+two French rings
+two ladies doves
+two ladies birds
+two ladies rings
+two pipers doves
+two pipers birds
+two pipers rings
+six turtle doves
+six turtle birds
+six turtle rings
+six French doves
+six French birds
+six French rings
+six ladies doves
+six ladies birds
+six ladies rings
+six pipers doves
+six pipers birds
+six pipers rings
+ten turtle doves
+ten turtle birds
+ten turtle rings
+ten French doves
+ten French birds
+ten French rings
+ten ladies doves
+ten ladies birds
+ten ladies rings
+ten pipers doves
+ten pipers birds
+ten pipers rings
+
+
+three turtle hens
+three French hens
+three ladies hens
+three pipers hens
+seven turtle hens
+seven French hens
+seven ladies hens
+seven pipers hens
+eight turtle hens
+eight French hens
+eight ladies hens
+eight pipers hens
+
+
+four calling doves
+four calling birds
+four calling rings
+five calling doves
+five calling birds
+five calling rings
+nine calling doves
+nine calling birds
+nine calling rings
+
+
+four gold doves
+four gold birds
+four gold rings
+five gold doves
+five gold birds
+five gold rings 
+nine gold doves
+nine gold birds
+nine gold rings
+
+
+two geese a-laying 
+two geese drumming
+two swans a-laying
+two swans drumming
+two maids a-laying
+two maids drumming
+two lords a-laying
+two lords drumming
+six geese a-laying
+six geese drumming
+six swans a-laying
+six swans drumming
+six maids a-laying
+six maids drumming
+six lords a-laying
+six lords drumming
+ten geese a-laying
+ten geese drumming
+ten swans a-laying
+ten swans drumming
+ten maids a-laying
+ten maids drumming
+ten lords a-laying
+ten lords drumming
+
+
+three geese a-swimming
+three swans a-swimming
+three maids a-swimming
+three lords a-swimming
+seven geese a-swimming
+seven swans a-swimming
+seven maids a-swimming
+seven lords a-swimming
+eight geese a-swimming
+eight swans a-swimming
+eight maids a-swimming
+eight lords a-swimming
+
+
+three geese a-milking
+three geese a-leaping
+three swans a-milking
+three swans a-leaping
+three maids a-milking
+three maids a-leaping
+three lords a-milking
+three lords a-leaping
+seven geese a-milking
+seven geese a-leaping
+seven swans a-milking
+seven swans a-leaping
+seven maids a-milking
+seven maids a-leaping
+seven lords a-milking
+seven lords a-leaping
+eight geese a-milking
+eight geese a-leaping
+eight swans a-milking
+eight swans a-leaping
+eight maids a-milking
+eight maids a-leaping
+eight lords a-milking
+eight lords a-leaping
+
+
+four turtle dancing
+four French dancing
+four ladies dancing
+four pipers dancing
+five turtle dancing
+five French dancing
+five ladies dancing
+five pipers dancing
+nine turtle dancing
+nine French dancing
+nine ladies dancing
+nine pipers dancing
+
+
+two geese a-milking
+two geese a-leaping
+two swans a-milking
+two swans a-leaping
+two maids a-milking
+two maids a-leaping
+two lords a-milking
+two lords a-leaping
+six geese a-milking
+six geese a-leaping
+six swans a-milking
+six swans a-leaping
+six maids a-milking
+six maids a-leaping
+six lords a-milking
+six lords a-leaping
+ten geese a-milking
+ten geese a-leaping
+ten swans a-milking
+ten swans a-leaping
+ten maids a-milking
+ten maids a-leaping
+ten lords a-milking
+ten lords a-leaping
+
+
+eleven turtle piping
+eleven French piping
+eleven ladies piping
+eleven pipers piping
+twelve turtle piping
+twelve French piping
+twelve ladies piping
+twelve pipers piping
+
+
+eleven drummers a-laying
+eleven drummers drumming
+twelve drummers a-laying
+twelve drummers drumming
+```

app/Main.hs

@@ -2,7 +2,6 @@ module Main (main) where
 
 ordinals :: [ String ]
 ordinals = [
-    "first",
     "second",
     "third",
     "fourth",
@@ -16,20 +15,34 @@ ordinals = [
     "twelfth"
     ]
 
+signatures :: [ ( Int, Int, Int, Int) ]
+signatures = [
+    ( 3, 6, 5, 0 ),
+    ( 5, 6, 4, 1 ),
+    ( 4, 7, 5, 1 ),
+    ( 4, 4, 5, 5 ),
+    ( 3, 5, 8, 8 ),
+    ( 5, 5, 10, 5 ),
+    ( 5, 5, 9, 20 ),
+    ( 4, 6, 7, 10 ),
+    ( 3, 5, 9, 23 ),
+    ( 6, 6, 6, 3 ),
+    ( 6, 8, 8, 3 )
+    ]
 
 cardinals :: [ String ]
 cardinals = [
-    "two",
+    "Two",
-    "three",
+    "Three",
-    "four",
+    "Four",
-    "five",
+    "Five",
-    "six",
+    "Six",
-    "seven",
+    "Seven",
-    "eight",
+    "Eight",
-    "nine",
+    "Nine",
-    "ten",
+    "Ten",
-    "eleven",
+    "Eleven",
-    "twelve"
+    "Twelve"
     ]
 
 
@@ -63,21 +76,6 @@ giftb = [
     "drumming"
     ]
 
-signatures :: [ ( Int, Int, Int, Int) ]
-signatures = [
-    ( 3, 6, 5, 0 ),
-    ( 5, 6, 4, 1 ),
-    ( 4, 7, 5, 1 ),
-    ( 4, 4, 5, 5 ),
-    ( 3, 5, 8, 8 ),
-    ( 5, 5, 10, 5 ),
-    ( 5, 5, 9, 20 ),
-    ( 4, 6, 7, 10 ),
-    ( 3, 5, 9, 23 ),
-    ( 6, 6, 6, 3 ),
-    ( 6, 8, 8, 3 )
-    ]
-
 gifts :: [ ( String, String, String ) ]
 gifts = [ ( c, a, b ) | c <- cardinals, a <- gifta, b <- giftb ]
 
@@ -94,11 +92,32 @@ wrapGift (i, j, k, l) = gs !! l
     where
         gs = map giftStr $ matchGifts (i, j, k)
 
-wrapGifts :: String
+concatLines :: [ String ] -> String
-wrapGifts = foldr (\a b -> a ++ "\n" ++ b) "" gs
+concatLines ls = foldr (\a b -> a ++ "\n" ++ b) "" ls
+
+opening :: String -> String
+opening o = "On the " ++ o ++ " day of Christmas my true love gave to me\n"
+
+partridge :: String
+partridge = "partridge in a pear tree"
+
+makeVerse :: String -> [ String ] -> String
+makeVerse o [] = (opening o) ++ "A " ++ partridge
+makeVerse o gs = (opening o) ++ (concatLines gs) ++ "And a " ++ partridge
+
+allGifts :: [ String ]
+allGifts = map wrapGift $ reverse signatures
+
+recurseVerse :: [ ( String, String ) ] -> [ String ]
+recurseVerse [] = [ makeVerse "first" [] ]
+recurseVerse (t:ts) = [ (makeVerse ord gs) ] ++ (recurseVerse ts)
     where
-        gs = map wrapGift signatures
+        ord = fst t
+        gs = [(snd t)] ++ (map snd ts)
+
+tuples :: [ ( String, String ) ]
+tuples = zip (reverse ordinals) allGifts
 
 
 main :: IO ()
-main = putStrLn wrapGifts
+main = putStrLn $ foldr (\a b -> a ++ "\n\n" ++ b) "" $ reverse $ recurseVerse tuples

package.yaml

@@ -0,0 +1,59 @@
+name:                xmasTwelve
+version:             0.1.0.0
+github:              "githubuser/xmasTwelve"
+license:             BSD-3-Clause
+author:              "Author name here"
+maintainer:          "example@example.com"
+copyright:           "2025 Author name here"
+
+extra-source-files:
+- README.md
+- CHANGELOG.md
+
+# Metadata used when publishing your package
+# synopsis:            Short description of your package
+# category:            Web
+
+# To avoid duplicated efforts in documentation and dealing with the
+# complications of embedding Haddock markup inside cabal files, it is
+# common to point users to the README.md file.
+description:         Please see the README on GitHub at <https://github.com/githubuser/xmasTwelve#readme>
+
+dependencies:
+- base >= 4.7 && < 5
+
+ghc-options:
+- -Wall
+- -Wcompat
+- -Widentities
+- -Wincomplete-record-updates
+- -Wincomplete-uni-patterns
+- -Wmissing-export-lists
+- -Wmissing-home-modules
+- -Wpartial-fields
+- -Wredundant-constraints
+
+library:
+  source-dirs: src
+
+executables:
+  xmasTwelve-exe:
+    main:                Main.hs
+    source-dirs:         app
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - xmasTwelve
+
+tests:
+  xmasTwelve-test:
+    main:                Spec.hs
+    source-dirs:         test
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - xmasTwelve