Add food-chain exercise

config.json

@@ -265,6 +265,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "food-chain",
+        "name": "Food Chain",
+        "uuid": "48601e2b-bae3-4133-901f-6df39936b04f",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "grains",
         "name": "Grains",

exercises/practice/food-chain/.docs/instructions.md

@@ -0,0 +1,64 @@
+# Instructions
+
+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][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!
+```
+
+[cumulative-song]: https://en.wikipedia.org/wiki/Cumulative_song

exercises/practice/food-chain/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "food-chain.ua"
+    ],
+    "test": [
+      "tests.ua"
+    ],
+    "example": [
+      ".meta/example.ua"
+    ]
+  },
+  "blurb": "Generate the lyrics of the song 'I Know an Old Lady Who Swallowed a Fly'.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/There_Was_an_Old_Lady_Who_Swallowed_a_Fly"
+}

exercises/practice/food-chain/.meta/example.ua

@@ -0,0 +1,21 @@
+Animals ← {"fly" "spider" "bird" "cat" "dog" "goat" "cow" "horse"}
+Phrases ← {
+  ""
+  "It 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!"
+  ""
+}
+
+VerseBegin     ← |1 ▽>0∵(⧻°□) . ⊂⊃(□$"I know an old lady who swallowed a _." ⊡ : Animals|⊡ : Phrases)
+VerseCatch     ← |1 ⨬(∘|$"_ that wriggled and jiggled and tickled inside her")≍"spider".
+VerseSwallow   ← |2 □$"She swallowed the _ to catch the _." ⊙(VerseCatch°□)
+VerseSwalllows ← |1 ≡(VerseSwallow ⊃(⊡ 1|⊡ 0)) ⇌↙ ⊙(◫2 Animals)
+VerseMiddle    ← |1 ⨬({})(VerseSwalllows)×⊃(>0|<7).
+VerseEnd       ← |1 □⨬("She's dead, of course!"|"I don't know why she swallowed the fly. Perhaps she'll die.") <7
+Verse          ← |1 □⊂⊃(⊂⊃(VerseBegin|VerseMiddle)|VerseEnd)
+Verses         ← |2 ≡Verse ⇌⍜-⇡ -1
+Recite         ← |2 ⍜⇌(↘1) ∧(⊂⊂ : {""}°□) : {} Verses

exercises/practice/food-chain/.meta/tests.toml

@@ -0,0 +1,40 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[751dce68-9412-496e-b6e8-855998c56166]
+description = "fly"
+
+[6c56f861-0c5e-4907-9a9d-b2efae389379]
+description = "spider"
+
+[3edf5f33-bef1-4e39-ae67-ca5eb79203fa]
+description = "bird"
+
+[e866a758-e1ff-400e-9f35-f27f28cc288f]
+description = "cat"
+
+[3f02c30e-496b-4b2a-8491-bc7e2953cafb]
+description = "dog"
+
+[4b3fd221-01ea-46e0-825b-5734634fbc59]
+description = "goat"
+
+[1b707da9-7001-4fac-941f-22ad9c7a65d4]
+description = "cow"
+
+[3cb10d46-ae4e-4d2c-9296-83c9ffc04cdc]
+description = "horse"
+
+[22b863d5-17e4-4d1e-93e4-617329a5c050]
+description = "multiple verses"
+
+[e626b32b-745c-4101-bcbd-3b13456893db]
+description = "full song"

exercises/practice/food-chain/food-chain.ua

@@ -0,0 +1,3 @@
+# Generates the food chain rhyme
+# Lines ? StartVerse EndVerse
+Recite ← |2 ⊙(⍤ "Please implement Recite")

exercises/practice/food-chain/tests.ua

@@ -0,0 +1,158 @@
+~ "food-chain.ua" ~ Recite
+
+# fly
+Expected ← {
+  "I know an old lady who swallowed a fly."
+  "I don't know why she swallowed the fly. Perhaps she'll die."
+}
+⍤⤙≍ Expected Recite 1 1
+
+# spider
+Expected ← {
+  "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."
+}
+⍤⤙≍ Expected Recite 2 2
+
+# bird
+Expected ← {
+  "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."
+}
+⍤⤙≍ Expected Recite 3 3
+
+# cat
+Expected ← {
+  "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."
+}
+⍤⤙≍ Expected Recite 4 4
+
+# dog
+Expected ← {
+  "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."
+}
+⍤⤙≍ Expected Recite 5 5
+
+# goat
+Expected ← {
+  "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."
+}
+⍤⤙≍ Expected Recite 6 6
+
+# cow
+Expected ← {
+  "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."
+}
+⍤⤙≍ Expected Recite 7 7
+
+# horse
+Expected ← {
+  "I know an old lady who swallowed a horse."
+  "She's dead, of course!"
+}
+⍤⤙≍ Expected Recite 8 8
+
+# multiple verses
+Expected ← {
+  "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."
+}
+⍤⤙≍ Expected Recite 1 3
+
+# full song
+Expected ← {
+  "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!"
+}
+
+⍤⤙≍ Expected Recite 1 8