Exercise: Proverb (#742)

* Update config.json
* Encourage a multi-dispatch approach

config.json

@@ -735,6 +735,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 1
+      },
+      {
+        "slug": "proverb",
+        "name": "Proverb",
+        "uuid": "ef243fad-2ac8-4313-a484-1c28a6d7ab21",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 1
       }
     ]
   },

exercises/practice/proverb/.docs/instructions.md

@@ -0,0 +1,19 @@
+# Instructions
+
+For want of a horseshoe nail, a kingdom was lost, or so the saying goes.
+
+Given a list of inputs, generate the relevant proverb.
+For example, given the list `["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"]`, you will output the full text of this proverbial rhyme:
+
+```text
+For want of a nail the shoe was lost.
+For want of a shoe the horse was lost.
+For want of a horse the rider was lost.
+For want of a rider the message was lost.
+For want of a message the battle was lost.
+For want of a battle the kingdom was lost.
+And all for the want of a nail.
+```
+
+Note that the list of inputs may vary; your solution should be able to handle lists of arbitrary length and content.
+No line of the output text should be a static, unchanging string; all should vary according to the input given.

exercises/practice/proverb/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "habere-et-dispertire"
+  ],
+  "files": {
+    "solution": [
+      "lib/Proverb.rakumod"
+    ],
+    "test": [
+      "t/proverb.rakutest"
+    ],
+    "example": [
+      ".meta/solutions/lib/Proverb.rakumod"
+    ]
+  },
+  "blurb": "For want of a horseshoe nail, a kingdom was lost, or so the saying goes. Output the full text of this proverbial rhyme.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/For_Want_of_a_Nail"
+}

exercises/practice/proverb/.meta/solutions/lib/Proverb.rakumod

@@ -0,0 +1,13 @@
+unit module Proverb;
+
+multi recite ( $noun where $_ eq '' ) is export { }
+multi recite ( $noun where $_ ne '' ) {
+  "And all for the want of a $noun."
+}
+multi recite ( @nouns ) {
+  join "\n",
+  @nouns
+  .rotor(2=>-1)
+  .map( { "For want of a {.head} the {.tail} was lost." } ),
+  recite @nouns.head
+}

exercises/practice/proverb/.meta/solutions/t/proverb.rakutest

@@ -0,0 +1 @@
+../../../t/proverb.rakutest

exercises/practice/proverb/.meta/template-data.yaml

@@ -0,0 +1,30 @@
+properties:
+  recite:
+    test: |-
+      sprintf(q :to 'END', %case<input><strings>.Array.raku, %case<expected>.join("\n").raku, %case<description>.raku);
+        cmp-ok(
+          recite(%s),
+          "eq",
+          %s,
+          %s,
+        );
+        END
+
+
+unit: module
+example: |-
+  multi recite ( $noun where $_ eq '' ) is export { }
+  multi recite ( $noun where $_ ne '' ) {
+    "And all for the want of a $noun."
+  }
+  multi recite ( @nouns ) {
+    join "\n",
+    @nouns
+    .rotor(2=>-1)
+    .map( { "For want of a {.head} the {.tail} was lost." } ),
+    recite @nouns.head
+  }
+
+stub: |-
+  sub proverb (@nouns) is export {
+  }

exercises/practice/proverb/.meta/tests.toml

@@ -0,0 +1,28 @@
+# 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.
+
+[e974b73e-7851-484f-8d6d-92e07fe742fc]
+description = "zero pieces"
+
+[2fcd5f5e-8b82-4e74-b51d-df28a5e0faa4]
+description = "one piece"
+
+[d9d0a8a1-d933-46e2-aa94-eecf679f4b0e]
+description = "two pieces"
+
+[c95ef757-5e94-4f0d-a6cb-d2083f5e5a83]
+description = "three pieces"
+
+[433fb91c-35a2-4d41-aeab-4de1e82b2126]
+description = "full proverb"
+
+[c1eefa5a-e8d9-41c7-91d4-99fab6d6b9f7]
+description = "four pieces modernized"

exercises/practice/proverb/lib/Proverb.rakumod

@@ -0,0 +1,4 @@
+unit module Proverb;
+
+sub proverb (@nouns) is export {
+}

exercises/practice/proverb/t/proverb.rakutest

@@ -0,0 +1,48 @@
+#!/usr/bin/env raku
+use Test;
+use lib $?FILE.IO.parent(2).add('lib');
+use Proverb;
+
+cmp-ok( # begin: e974b73e-7851-484f-8d6d-92e07fe742fc
+  recite([]),
+  "eq",
+  "",
+  "zero pieces",
+); # end: e974b73e-7851-484f-8d6d-92e07fe742fc
+
+cmp-ok( # begin: 2fcd5f5e-8b82-4e74-b51d-df28a5e0faa4
+  recite(["nail"]),
+  "eq",
+  "And all for the want of a nail.",
+  "one piece",
+); # end: 2fcd5f5e-8b82-4e74-b51d-df28a5e0faa4
+
+cmp-ok( # begin: d9d0a8a1-d933-46e2-aa94-eecf679f4b0e
+  recite(["nail", "shoe"]),
+  "eq",
+  "For want of a nail the shoe was lost.\nAnd all for the want of a nail.",
+  "two pieces",
+); # end: d9d0a8a1-d933-46e2-aa94-eecf679f4b0e
+
+cmp-ok( # begin: c95ef757-5e94-4f0d-a6cb-d2083f5e5a83
+  recite(["nail", "shoe", "horse"]),
+  "eq",
+  "For want of a nail the shoe was lost.\nFor want of a shoe the horse was lost.\nAnd all for the want of a nail.",
+  "three pieces",
+); # end: c95ef757-5e94-4f0d-a6cb-d2083f5e5a83
+
+cmp-ok( # begin: 433fb91c-35a2-4d41-aeab-4de1e82b2126
+  recite(["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"]),
+  "eq",
+  "For want of a nail the shoe was lost.\nFor want of a shoe the horse was lost.\nFor want of a horse the rider was lost.\nFor want of a rider the message was lost.\nFor want of a message the battle was lost.\nFor want of a battle the kingdom was lost.\nAnd all for the want of a nail.",
+  "full proverb",
+); # end: 433fb91c-35a2-4d41-aeab-4de1e82b2126
+
+cmp-ok( # begin: c1eefa5a-e8d9-41c7-91d4-99fab6d6b9f7
+  recite(["pin", "gun", "soldier", "battle"]),
+  "eq",
+  "For want of a pin the gun was lost.\nFor want of a gun the soldier was lost.\nFor want of a soldier the battle was lost.\nAnd all for the want of a pin.",
+  "four pieces modernized",
+); # end: c1eefa5a-e8d9-41c7-91d4-99fab6d6b9f7
+
+done-testing;