Implement exercise food-chain

config.json

@@ -955,6 +955,18 @@
         "stacks"
       ]
     },
+    {
+      "uuid": "f229746e-5ea9-4774-b3e0-9b9c2ebf9558",
+      "slug": "food-chain",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 4,
+      "topics": [
+        "algorithms",
+        "loops",
+        "conditionals"
+      ]
+    },
     {
       "uuid": "e7351e8e-d3ff-4621-b818-cd55cf05bffd",
       "slug": "accumulate",

exercises/food-chain/README.md

@@ -0,0 +1,81 @@
+# Food chain
+
+Generate the lyrics of the song 'I Know an Old Lady Who Swallowed a Fly'.
+
+While you could copy/paste the lyrics,
+or read them from a file, this problem is much more
+interesting if you approach it algorithmically.
+
+This is a [cumulative song](http://en.wikipedia.org/wiki/Cumulative_song) of unknown origin.
+
+This is one of many common variants.
+
+```text
+I know an old lady who swallowed a fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a spider.
+It wriggled and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a bird.
+How absurd to swallow a bird!
+She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a cat.
+Imagine that, to swallow a cat!
+She swallowed the cat to catch the bird.
+She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a dog.
+What a hog, to swallow a dog!
+She swallowed the dog to catch the cat.
+She swallowed the cat to catch the bird.
+She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a goat.
+Just opened her throat and swallowed a goat!
+She swallowed the goat to catch the dog.
+She swallowed the dog to catch the cat.
+She swallowed the cat to catch the bird.
+She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a cow.
+I don't know how she swallowed a cow!
+She swallowed the cow to catch the goat.
+She swallowed the goat to catch the dog.
+She swallowed the dog to catch the cat.
+She swallowed the cat to catch the bird.
+She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a horse.
+She's dead, of course!
+```
+
+### Submitting Exercises
+
+Note that, when trying to submit an exercise, make sure the solution is in the `exercism/python/<exerciseName>` directory.
+
+For example, if you're submitting `bob.py` for the Bob exercise, the submit command would be something like `exercism submit <path_to_exercism_dir>/python/bob/bob.py`.
+
+
+For more detailed information about running tests, code style and linting,
+please see the [help page](http://exercism.io/languages/python).
+
+## Source
+
+Inspired by the Extreme Startup game [https://github.com/rchatley/extreme_startup](https://github.com/rchatley/extreme_startup)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

exercises/food-chain/example.py

@@ -0,0 +1,45 @@
+def chain():
+
+    animals = ["fly", "spider", "bird", "cat", "dog", "goat", "cow", "horse"]
+
+    phrases = [" wriggled and jiggled and tickled inside her.",
+               "How absurd to swallow a bird!",
+               "Imagine that, to swallow a cat!",
+               "What a hog, to swallow a dog!",
+               "Just opened her throat and swallowed a goat!",
+               "I don't know how she swallowed a cow!",
+               "She's dead, of course!"]
+
+    old_lady = "I know an old lady who swallowed a "
+    swallowed = "She swallowed the <animal> to catch the "
+    die = "I don't know why she swallowed the fly. Perhaps she'll die."
+
+    song = ""
+    verse = ""
+    chain = ""
+
+    for number, animal in enumerate(animals):
+        verse = old_lady + animal + ".\n"
+
+        if number == 7:
+            verse += phrases[6]
+        else:
+            if number == 0:
+                chain = swallowed + animal + '.\n'
+            elif number == 1:
+                verse += "It" + phrases[0] + "\n"
+                chain = chain.replace("<animal>", animal)
+                verse += chain
+                chain = swallowed+animal+" that"+phrases[0]+"\n"+chain
+            else:
+                verse += phrases[number-1] + "\n"
+                chain = chain.replace("<animal>", animal)
+                verse += chain
+                chain = swallowed + animal + ".\n" + chain
+
+            verse += die + "\n"
+
+        verse += "\n"
+        song += verse
+
+    return song

exercises/food-chain/food_chain.py

@@ -0,0 +1,2 @@
+def chain():
+    pass

exercises/food-chain/food_chain_test.py

@@ -0,0 +1,109 @@
+import unittest
+
+from food_chain import chain
+
+# Tests adapted from `problem-specifications//canonical-data.json` @ v1.0.0
+
+song = """I know an old lady who swallowed a fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a spider.
+It wriggled and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a bird.
+How absurd to swallow a bird!
+She swallowed the bird to catch the spider that wriggled
+and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a cat.
+Imagine that, to swallow a cat!
+She swallowed the cat to catch the bird.
+She swallowed the bird to catch the spider that wriggled
+and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a dog.
+What a hog, to swallow a dog!
+She swallowed the dog to catch the cat.
+She swallowed the cat to catch the bird.
+She swallowed the bird to catch the spider that wriggled
+and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a goat.
+Just opened her throat and swallowed a goat!
+She swallowed the goat to catch the dog.
+She swallowed the dog to catch the cat.
+She swallowed the cat to catch the bird.
+She swallowed the bird to catch the spider that wriggled
+and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a cow.
+I don't know how she swallowed a cow!
+She swallowed the cow to catch the goat.
+She swallowed the goat to catch the dog.
+She swallowed the dog to catch the cat.
+She swallowed the cat to catch the bird.
+She swallowed the bird to catch the spider that wriggled
+and jiggled and tickled inside her.
+She swallowed the spider to catch the fly.
+I don't know why she swallowed the fly. Perhaps she'll die.
+
+I know an old lady who swallowed a horse.
+She's dead, of course!"""
+
+
+def verses(letter):
+    return letter.replace('die.', 'die.slice').split('slice')
+
+
+original = [verse.replace("\n", "").replace(" ", "").lower()
+            for verse in verses(song)]
+
+generated = [verse.replace("\n", "").replace(" ", "").lower()
+             for verse in verses(chain())]
+
+
+class FoodChainTest(unittest.TestCase):
+
+    def test_fly(self):
+        self.assertEqual(original[0], generated[0])
+
+    def test_spider(self):
+        self.assertEqual(original[1], generated[1])
+
+    def test_bird(self):
+        self.assertEqual(original[2], generated[2])
+
+    def test_cat(self):
+        self.assertEqual(original[3], generated[3])
+
+    def test_dog(self):
+        self.assertEqual(original[4], generated[4])
+
+    def test_goat(self):
+        self.assertEqual(original[5], generated[5])
+
+    def test_cow(self):
+        self.assertEqual(original[6], generated[6])
+
+    def test_horse(self):
+        self.assertEqual(original[7], generated[7])
+
+    def test_multiple_verses(self):
+        self.assertEqual(original[0:3], generated[0:3])
+
+    def test_full_song(self):
+        self.assertEqual(original, generated)
+
+
+if __name__ == '__main__':
+    unittest.main()