Added twelve-days haskell exercise

config.json

@@ -266,6 +266,15 @@
         "Maybe"
       ]
     },
+    {
+      "uuid": "d1dc946d-a142-42ed-abec-e53605635c0d",
+      "slug": "twelve-days",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 3,
+      "topics": [
+      ]
+    },
     {
       "uuid": "382e4fbd-99d6-400b-962c-ebb4a411bcea",
       "slug": "beer-song",

exercises/twelve-days/README.md

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+# Twelve Days
+
+Output the lyrics to 'The Twelve Days of Christmas'.
+
+```text
+On the first day of Christmas my true love gave to me, a Partridge in a Pear Tree.
+
+On the second day of Christmas my true love gave to me, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the third day of Christmas my true love gave to me, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fourth day of Christmas my true love gave to me, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fifth day of Christmas my true love gave to me, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the sixth day of Christmas my true love gave to me, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the seventh day of Christmas my true love gave to me, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eighth day of Christmas my true love gave to me, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the ninth day of Christmas my true love gave to me, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the tenth day of Christmas my true love gave to me, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eleventh day of Christmas my true love gave to me, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the twelfth day of Christmas my true love gave to me, twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+```
+
+
+## Getting Started
+
+For installation and learning resources, refer to the
+[exercism help page](http://exercism.io/languages/haskell).
+
+## Running the tests
+
+To run the test suite, execute the following command:
+
+```bash
+stack test
+```
+
+#### If you get an error message like this...
+
+```
+No .cabal file found in directory
+```
+
+You are probably running an old stack version and need
+to upgrade it.
+
+#### Otherwise, if you get an error message like this...
+
+```
+No compiler found, expected minor version match with...
+Try running "stack setup" to install the correct GHC...
+```
+
+Just do as it says and it will download and install
+the correct compiler version:
+
+```bash
+stack setup
+```
+
+## Running *GHCi*
+
+If you want to play with your solution in GHCi, just run the command:
+
+```bash
+stack ghci
+```
+
+## Feedback, Issues, Pull Requests
+
+The [exercism/haskell](https://github.com/exercism/haskell) repository on
+GitHub is the home for all of the Haskell exercises.
+
+If you have feedback about an exercise, or want to help implementing a new
+one, head over there and create an issue.  We'll do our best to help you!
+
+## Source
+
+Wikipedia [http://en.wikipedia.org/wiki/The_Twelve_Days_of_Christmas_(song)](http://en.wikipedia.org/wiki/The_Twelve_Days_of_Christmas_(song))
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

exercises/twelve-days/examples/success-standard/package.yaml

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+name: twelve-days
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: TwelveDays
+  source-dirs: src
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - twelve-days
+      - hspec

exercises/twelve-days/examples/success-standard/src/TwelveDays.hs

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+module TwelveDays (recite) where
+
+recite :: Int -> Int -> [String]
+recite start stop
+  | start <= stop = lyrics start : recite (start + 1) stop
+  | otherwise     = []
+
+lyrics :: Int -> String
+lyrics days =
+  beginning ++ end days
+  where
+    beginning =
+      let (day, _) = verse days
+      in "On the " ++ day ++ " day of Christmas my true love gave to me"
+    end days'
+      | days < 13 && days' > 0 = let (_, gift) = verse days'
+                                 in prefix days' ++ gift ++ end (days' - 1)
+      | otherwise              = "."
+      where
+        prefix 1 = if days > 1 then ", and " else ", "
+        prefix _ = ", "
+
+verse :: Int -> (String, String)
+verse 12 = ("twelfth", "twelve Drummers Drumming")
+verse 11 = ("eleventh", "eleven Pipers Piping")
+verse 10 = ("tenth", "ten Lords-a-Leaping")
+verse  9 = ("ninth", "nine Ladies Dancing")
+verse  8 = ("eighth", "eight Maids-a-Milking")
+verse  7 = ("seventh", "seven Swans-a-Swimming")
+verse  6 = ("sixth", "six Geese-a-Laying")
+verse  5 = ("fifth", "five Gold Rings")
+verse  4 = ("fourth", "four Calling Birds")
+verse  3 = ("third", "three French Hens")
+verse  2 = ("second", "two Turtle Doves")
+verse  1 = ("first", "a Partridge in a Pear Tree")
+verse  _ = ("", "")

exercises/twelve-days/package.yaml

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+name: twelve-days
+version: 1.0.0.1
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: TwelveDays
+  source-dirs: src
+  dependencies:
+  # - foo       # List here the packages you
+  # - bar       # want to use in your solution.
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - twelve-days
+      - hspec

exercises/twelve-days/src/TwelveDays.hs

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+module TwelveDays (recite) where
+
+recite :: Int -> Int -> [String]
+recite start stop = error "You need to implement this function."

exercises/twelve-days/stack.yaml

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+resolver: lts-9.11

exercises/twelve-days/test/Tests.hs

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+{-# LANGUAGE RecordWildCards #-}
+
+import Data.Foldable     (for_)
+import Test.Hspec        (Spec, describe, it, shouldBe)
+import Test.Hspec.Runner (configFastFail, defaultConfig, hspecWith)
+
+import TwelveDays (recite)
+
+main :: IO ()
+main = hspecWith defaultConfig {configFastFail = True} specs
+
+specs :: Spec
+specs = describe "responseFor" $ for_ cases test
+  where
+      test Case{..} = it description assertion
+        where
+          assertion = recite start stop `shouldBe` expected
+
+data Case = Case { description :: String
+                 , start       :: Int
+                 , stop        :: Int
+                 , expected    :: [String]
+                 }
+
+cases :: [Case]
+cases = [ Case { description = "first day a partridge in a pear tree"
+               , start = 1
+               , stop = 1
+               , expected = [
+                   "On the first day of Christmas my true love gave to me, a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "second day two turtle doves"
+               , start = 2
+               , stop = 2
+               , expected = [
+                   "On the second day of Christmas my true love gave to me, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "third day three french hens"
+               , start = 3
+               , stop = 3
+               , expected = [
+                   "On the third day of Christmas my true love gave to me, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "fourth day four calling birds"
+               , start = 4
+               , stop = 4
+               , expected = [
+                   "On the fourth day of Christmas my true love gave to me, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "fifth day five gold rings"
+               , start = 5
+               , stop = 5
+               , expected = [
+                   "On the fifth day of Christmas my true love gave to me, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "sixth day six geese-a-laying"
+               , start = 6
+               , stop = 6
+               , expected = [
+                   "On the sixth day of Christmas my true love gave to me, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "seventh day seven swans-a-swimming"
+               , start = 7
+               , stop = 7
+               , expected = [
+                   "On the seventh day of Christmas my true love gave to me, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "eighth day eight maids-a-milking"
+               , start = 8
+               , stop = 8
+               , expected = [
+                   "On the eighth day of Christmas my true love gave to me, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "ninth day nine ladies dancing"
+               , start = 9
+               , stop = 9
+               , expected = [
+                   "On the ninth day of Christmas my true love gave to me, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "tenth day ten lords-a-leaping"
+               , start = 10
+               , stop = 10
+               , expected = [
+                   "On the tenth day of Christmas my true love gave to me, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "eleventh day eleven pipers piping"
+               , start = 11
+               , stop = 11
+               , expected = [
+                   "On the eleventh day of Christmas my true love gave to me, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "twelfth day twelve drummers drumming"
+               , start = 12
+               , stop = 12
+               , expected = [
+                   "On the twelfth day of Christmas my true love gave to me, twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "recites first three verses of the song"
+               , start = 1
+               , stop = 3
+               , expected = [
+                   "On the first day of Christmas my true love gave to me, a Partridge in a Pear Tree."
+                 , "On the second day of Christmas my true love gave to me, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the third day of Christmas my true love gave to me, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "recites three verses from the middle of the song"
+               , start = 4
+               , stop = 6
+               , expected = [
+                   "On the fourth day of Christmas my true love gave to me, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the fifth day of Christmas my true love gave to me, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the sixth day of Christmas my true love gave to me, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        , Case { description = "recites the whole song"
+               , start = 1
+               , stop = 12
+               , expected = [
+                   "On the first day of Christmas my true love gave to me, a Partridge in a Pear Tree."
+                 , "On the second day of Christmas my true love gave to me, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the third day of Christmas my true love gave to me, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the fourth day of Christmas my true love gave to me, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the fifth day of Christmas my true love gave to me, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the sixth day of Christmas my true love gave to me, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the seventh day of Christmas my true love gave to me, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the eighth day of Christmas my true love gave to me, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the ninth day of Christmas my true love gave to me, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the tenth day of Christmas my true love gave to me, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the eleventh day of Christmas my true love gave to me, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 , "On the twelfth day of Christmas my true love gave to me, twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+                 ]
+               }
+        ]