Add proverb exercise (#70)

Author: keiravillekode

config.json

@@ -385,6 +385,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "proverb",
+        "name": "Proverb",
+        "uuid": "901faf71-670a-4a8a-b948-e7df0b8ed248",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "run-length-encoding",
         "name": "Run-Length Encoding",

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

@@ -0,0 +1,12 @@
+def recite (strings: []u8): []u8 =
+  if length strings == 0 then [] else
+  let offsets = loop offsets = [0] for i < length strings do
+    if strings[i] != '\n' then offsets else
+    offsets ++ [i + 1]
+  in
+    let n = length offsets - 2
+    in
+      let result = loop result = "" for i < n do
+        result ++ "For want of a " ++ strings[offsets[i]:offsets[i + 1] - 1] ++ " the " ++ strings[offsets[i + 1]:offsets[i + 2] - 1] ++ " was lost.\n"
+      in
+        result ++ "And all for the want of a " ++ strings[offsets[0]:offsets[1] - 1] ++ ".\n"

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/proverb.fut

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

exercises/practice/proverb/test.fut

@@ -0,0 +1,34 @@
+import "proverb"
+
+-- zero pieces
+-- ==
+-- input { "" }
+-- output { "" }
+
+-- one piece
+-- ==
+-- input { "nail\n" }
+-- output { "And all for the want of a nail.\n" }
+
+-- two pieces
+-- ==
+-- input { "nail\nshoe\n" }
+-- output { "For want of a nail the shoe was lost.\nAnd all for the want of a nail.\n" }
+
+-- three pieces
+-- ==
+-- input { "nail\nshoe\nhorse\n" }
+-- output { "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.\n" }
+
+-- full proverb
+-- ==
+-- input { "nail\nshoe\nhorse\nrider\nmessage\nbattle\nkingdom\n" }
+-- output { "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.\n" }
+
+-- four pieces modernized
+-- ==
+-- input { "pin\ngun\nsoldier\nbattle\n" }
+-- output { "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.\n" }
+
+let main (strings: []u8): []u8 =
+  recite strings