add food-chain, part of 48 in 24

config.json

@@ -814,6 +814,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 5
+      },
+      {
+        "slug": "food-chain",
+        "name": "Food Chain",
+        "uuid": "ac1c0246-0fed-46e7-819a-0b013b2b4585",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
       }
     ]
   },

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": [
+    "kmarker1101"
+  ],
+  "files": {
+    "solution": [
+      "food-chain.el"
+    ],
+    "test": [
+      "food-chain-test.el"
+    ],
+    "example": [
+      ".meta/example.el"
+    ]
+  },
+  "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.el

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+;;; food-chain.el --- Food Chain (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+(defvar +creatures+ ["fly" "spider" "bird" "cat" "dog" "goat" "cow" "horse"])
+(defvar +unique-lines+ ["I don't know why she swallowed the fly. Perhaps she'll die."
+                        "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!"
+                        "She's dead, of course!"])
+
+(defun verse-end-p (index)
+  (or (= 7 index) (zerop index)))
+
+(defun add-lines (index)
+  (if (verse-end-p index)
+      (list (aref +unique-lines+ index))
+    (let* ((spider (if (= 2 index) " that wriggled and jiggled and tickled inside her" ""))
+           (creature (aref +creatures+ index))
+           (next-creature (aref +creatures+ (1- index)))
+           (line (format "She swallowed the %s to catch the %s%s." creature next-creature spider)))
+      (cons line (add-lines (1- index))))))
+
+(defun single-verse (index)
+  (let* ((start-line (format "I know an old lady who swallowed a %s." (aref +creatures+ index)))
+         (second-line (unless (verse-end-p index) (aref +unique-lines+ index)))
+         (verse-block (add-lines index)))
+    (if second-line
+        (cons start-line (cons second-line verse-block))
+      (cons start-line verse-block))))
+
+
+(defun recite (start-verse end-verse)
+  (let (output)
+    (cl-loop for index from (1- start-verse) below end-verse
+             do (setq output (append output (single-verse index) '(""))))
+    (butlast output 1)))  ;; Remove the last empty string added
+
+(provide 'food-chain)
+;;; food-chain.el ends here
+

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

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+# 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-test.el

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+;;; food-chain-test.el --- Food Chain (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+
+(load-file "food-chain.el")
+(declare-function recite "food-chain.el" (start-verse end-verse))
+
+
+(ert-deftest fly ()
+    (let ((expected '("I know an old lady who swallowed a fly."
+                    "I don't know why she swallowed the fly. Perhaps she'll die.")))
+    (should (equal (recite 1 1) expected))))
+
+(ert-deftest spider ()
+    (let ((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.")))
+    (should (equal (recite 2 2) expected))))
+
+
+(ert-deftest bird ()
+    (let ((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.")))
+    (should (equal (recite 3 3) expected))))
+
+
+(ert-deftest cat ()
+    (let ((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.")))
+    (should (equal (recite 4 4) expected))))
+
+
+(ert-deftest dog ()
+    (let ((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.")))
+    (should (equal (recite 5 5) expected))))
+
+
+(ert-deftest goat ()
+    (let ((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.")))
+    (should (equal (recite 6 6) expected))))
+
+
+(ert-deftest cow ()
+    (let ((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.")))
+    (should (equal (recite 7 7) expected))))
+
+
+(ert-deftest horse ()
+    (let ((expected '("I know an old lady who swallowed a horse."
+                    "She's dead, of course!")))
+    (should (equal (recite 8 8) expected))))
+
+
+(ert-deftest multiple-verses ()
+    (let ((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.")))
+    (should (equal (recite 1 3) expected))))
+
+
+(ert-deftest full-song ()
+    (let ((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!")))
+    (should (equal (recite 1 8) expected))))
+
+
+(provide 'food-chain-test)
+;;; food-chain-test.el ends here
+

exercises/practice/food-chain/food-chain.el

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+;;; food-chain.el --- Food Chain (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+
+(defun recite (end-verse start-verse)
+  (error "Delete this S-Expression and write your own implementation"))
+
+
+(provide 'food-chain)
+;;; food-chain.el ends here
+