Add food-chain exercise

bin/verify-exercises-in-docker

@@ -64,7 +64,7 @@ verify_exercise() {
         trap 'rm -rf "${tmpdir}"' EXIT    # remove tempdir when subshell ends
         cp -r "${dir}/." "${tmpdir}" || exit
         copy_example_or_exemplar_to_solution "${tmpdir}"
-        run_tests "${slug}" "${tmpdir}" || { cat "${tmpdir}/results.json"; exit 1; }
+        run_tests "${slug}" "${tmpdir}" || { jq . "${tmpdir}/results.json"; exit 1; }
     )
 }
 

config.json

@@ -569,6 +569,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "food-chain",
+        "name": "Food Chain",
+        "uuid": "4f7eea63-2cda-401c-af8c-b5007e5baffe",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "list-ops",
         "name": "List Ops",

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 +1,20 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "food-chain.scm"
+    ],
+    "test": [
+      "test.scm",
+      "test-util.ss"
+    ],
+    "example": [
+      ".meta/example.scm"
+    ]
+  },
+  "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.scm

@@ -0,0 +1,53 @@
+(import (rnrs))
+
+(define (recite-verse verse)
+  (define animals
+    '#(""
+       "fly"
+       "spider"
+       "bird"
+       "cat"
+       "dog"
+       "goat"
+       "cow"
+       "horse"))
+
+  (define exclamations
+    '#(""
+       "I don't know why she swallowed the fly. Perhaps she'll die."
+       "It wriggled and jiggled and tickled inside her.\n"
+       "How absurd to swallow a bird!\n"
+       "Imagine that, to swallow a cat!\n"
+       "What a hog, to swallow a dog!\n"
+       "Just opened her throat and swallowed a goat!\n"
+       "I don't know how she swallowed a cow!\n"
+       "She's dead, of course!"))
+
+  (define first-line
+    (string-append "I know an old lady who swallowed a " (vector-ref animals verse) ".\n"))
+
+  (define exclamation (vector-ref exclamations verse))
+
+  (define (suffix index)
+    (if (= index 2)
+      " that wriggled and jiggled and tickled inside her"
+      ""))
+
+  (if (< 1 verse 8)
+    (let loop ((index 1)
+               (result (vector-ref exclamations 1)))
+      (if (= index verse)
+        (string-append first-line exclamation result)
+        (loop (+ index 1)
+              (string-append "She swallowed the " (vector-ref animals (+ index 1))
+                             " to catch the " (vector-ref animals index) (suffix index) ".\n"
+                             result))))
+    (string-append first-line exclamation)))
+
+(define (recite start-verse end-verse)
+  (let loop ((verse end-verse)
+             (result '()))
+    (let ((result (cons (recite-verse verse) result)))
+      (if (= verse start-verse)
+        (apply string-append result)
+        (loop (- verse 1) (cons "\n\n" result))))))

exercises/practice/food-chain/.meta/template.j2

@@ -0,0 +1,13 @@
+{{ header }}
+
+(load "test-util.ss")
+
+(define test-cases
+  `(
+{%- for case in cases %}
+    (test-success "{{ loop.index }}. {{ case["description"] }}"
+        equal? recite '({{ case["input"]["startVerse"] }} {{ case["input"]["endVerse"] }})
+        "{{ case["expected"] | join("\n") }}"){% if not loop.last %}
+{% endif %}{% endfor %}))
+
+(run-with-cli "{{ name }}.scm" (list test-cases))

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/Makefile

@@ -0,0 +1,17 @@
+solution := 
+
+chez := scheme
+guile := guile
+
+help :
+	echo 'Run make chez or make guile'
+
+check-all : chez guile
+
+chez :
+	$(chez) --script test.scm $(solution)
+
+guile :
+	$(guile) test.scm $(solution)
+
+.PHONY : help check-all chez guile

exercises/practice/food-chain/food-chain.scm

@@ -0,0 +1,4 @@
+(import (rnrs))
+
+(define (recite start-verse end-verse)
+  'implement-me!)