Add food-chain exercise (#74)

Author: keiravillekode

config.json

@@ -441,6 +441,14 @@
         "prerequisites": [],
         "difficulty": 6
       },
+      {
+        "slug": "food-chain",
+        "name": "Food Chain",
+        "uuid": "38efaf36-0fd5-493b-ac3b-3662510e2d9a",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 6
+      },
       {
         "slug": "intergalactic-transmission",
         "name": "Intergalactic Transmission",

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": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "food_chain.fut"
+    ],
+    "test": [
+      "test.fut"
+    ],
+    "example": [
+      ".meta/example.fut"
+    ]
+  },
+  "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.fut

@@ -0,0 +1,28 @@
+def animals = "flyspiderbirdcatdoggoatcowhorse"
+
+def animal_offsets = map1 i64.i32 [0, 0, 3, 9, 13, 16, 19, 23, 26, 31, 31]
+
+def exclamations = "I don't know why she swallowed the fly. Perhaps she'll die.\nIt wriggled and jiggled and tickled inside her.\nHow absurd to swallow a bird!\nImagine that, to swallow a cat!\nWhat a hog, to swallow a dog!\nJust opened her throat and swallowed a goat!\nI don't know how she swallowed a cow!\nShe's dead, of course!\n"
+
+def exclamation_offsets = map1 i64.i32 [0, 0, 60, 108, 138, 170, 200, 245, 283, 306]
+
+def animal (verse: i64): []u8 =
+  copy animals[animal_offsets[verse]:animal_offsets[verse + 1]]
+
+def exclamation (verse: i64): []u8 =
+  copy exclamations[exclamation_offsets[verse]:exclamation_offsets[verse + 1]]
+
+def explanation (verse: i64): []u8 =
+  let result = loop result = "" for index in verse..(verse - 1)..>1 do
+    result ++ "She swallowed the " ++ (animal index) ++ " to catch the " ++ (animal (index - 1)) ++ (if index == 3 then " that wriggled and jiggled and tickled inside her" else "") ++ ".\n"
+  in
+    result ++ (exclamation 1)
+
+def stanza (verse: i64): []u8 =
+  "\nI know an old lady who swallowed a " ++ (animal verse) ++ ".\n" ++ (exclamation verse) ++ (if verse == 1 || verse == 8 then "" else explanation verse)
+
+def recite (start_verse: i32) (end_verse: i32): []u8 =
+  let result = loop result = "" for verse in start_verse...end_verse do
+    result ++ stanza (i64.i32 verse)
+  in
+    result[1:]

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.fut

@@ -0,0 +1 @@
+def recite (start_verse: i32) (end_verse: i32): []u8 = ???

exercises/practice/food-chain/test.fut

@@ -0,0 +1,54 @@
+import "food_chain"
+
+-- fly
+-- ==
+-- input { 1 1 }
+-- output { "I know an old lady who swallowed a fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n" }
+
+-- spider
+-- ==
+-- input { 2 2 }
+-- output { "I know an old lady who swallowed a spider.\nIt wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n" }
+
+-- bird
+-- ==
+-- input { 3 3 }
+-- output { "I know an old lady who swallowed a bird.\nHow absurd to swallow a bird!\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n" }
+
+-- cat
+-- ==
+-- input { 4 4 }
+-- output { "I know an old lady who swallowed a cat.\nImagine that, to swallow a cat!\nShe swallowed the cat to catch the bird.\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n" }
+
+-- dog
+-- ==
+-- input { 5 5 }
+-- output { "I know an old lady who swallowed a dog.\nWhat a hog, to swallow a dog!\nShe swallowed the dog to catch the cat.\nShe swallowed the cat to catch the bird.\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n" }
+
+-- goat
+-- ==
+-- input { 6 6 }
+-- output { "I know an old lady who swallowed a goat.\nJust opened her throat and swallowed a goat!\nShe swallowed the goat to catch the dog.\nShe swallowed the dog to catch the cat.\nShe swallowed the cat to catch the bird.\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n" }
+
+-- cow
+-- ==
+-- input { 7 7 }
+-- output { "I know an old lady who swallowed a cow.\nI don't know how she swallowed a cow!\nShe swallowed the cow to catch the goat.\nShe swallowed the goat to catch the dog.\nShe swallowed the dog to catch the cat.\nShe swallowed the cat to catch the bird.\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n" }
+
+-- horse
+-- ==
+-- input { 8 8 }
+-- output { "I know an old lady who swallowed a horse.\nShe's dead, of course!\n" }
+
+-- multiple verses
+-- ==
+-- input { 1 3 }
+-- output { "I know an old lady who swallowed a fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a spider.\nIt wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a bird.\nHow absurd to swallow a bird!\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n" }
+
+-- full song
+-- ==
+-- input { 1 8 }
+-- output { "I know an old lady who swallowed a fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a spider.\nIt wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a bird.\nHow absurd to swallow a bird!\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a cat.\nImagine that, to swallow a cat!\nShe swallowed the cat to catch the bird.\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a dog.\nWhat a hog, to swallow a dog!\nShe swallowed the dog to catch the cat.\nShe swallowed the cat to catch the bird.\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a goat.\nJust opened her throat and swallowed a goat!\nShe swallowed the goat to catch the dog.\nShe swallowed the dog to catch the cat.\nShe swallowed the cat to catch the bird.\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a cow.\nI don't know how she swallowed a cow!\nShe swallowed the cow to catch the goat.\nShe swallowed the goat to catch the dog.\nShe swallowed the dog to catch the cat.\nShe swallowed the cat to catch the bird.\nShe swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\nShe swallowed the spider to catch the fly.\nI don't know why she swallowed the fly. Perhaps she'll die.\n\nI know an old lady who swallowed a horse.\nShe's dead, of course!\n" }
+
+let main (start_verse: i32) (end_verse: i32): []u8 =
+  recite start_verse end_verse