Add grains exercise

config.json

@@ -421,6 +421,17 @@
           "blocks"
         ],
         "difficulty": 9
+      },
+      {
+        "slug": "grains",
+        "name": "Grains",
+        "uuid": "668915db-bc3d-4ff4-a339-174ed2f35940",
+        "practices": [
+          "errors",
+          "loops"
+        ],
+        "prerequisites": [],
+        "difficulty": 3
       }
     ]
   }

exercises/practice/grains/.docs/instructions.md

@@ -0,0 +1,15 @@
+# Instructions
+
+Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.
+
+There once was a wise servant who saved the life of a prince.
+The king promised to pay whatever the servant could dream up.
+Knowing that the king loved chess, the servant told the king he would like to have grains of wheat.
+One grain on the first square of a chess board, with the number of grains doubling on each successive square.
+
+There are 64 squares on a chessboard (where square 1 has one grain, square 2 has two grains, and so on).
+
+Write code that shows:
+
+- how many grains were on a given square, and
+- the total number of grains on the chessboard

exercises/practice/grains/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "grains.red"
+    ],
+    "test": [
+      "grains-test.red"
+    ],
+    "example": [
+      ".meta/example.red"
+    ]
+  },
+  "blurb": "Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.",
+  "source": "The CodeRanch Cattle Drive, Assignment 6",
+  "source_url": "https://coderanch.com/wiki/718824/Grains"
+}

exercises/practice/grains/.meta/example.red

@@ -0,0 +1,24 @@
+Red [
+	description: {"Grains" exercise solution for exercism platform}
+	author: "BNAndras"
+]
+
+square: function [
+	"Returns the number of grains on a given square"
+	square [integer!]
+	return: [integer!]
+] [
+	if (square < 1) or (square > 64) [
+		cause-error 'user 'message "square must be between 1 and 64"
+	]
+
+	power 2 (square - 1)
+]
+
+total: function [
+	"Returns the total number of grains on a chessboard"
+	return: [integer!]
+] [
+	(power 2 64) - 1
+]
+

exercises/practice/grains/.meta/tests.toml

@@ -0,0 +1,43 @@
+# 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.
+
+[9fbde8de-36b2-49de-baf2-cd42d6f28405]
+description = "returns the number of grains on the square -> grains on square 1"
+
+[ee1f30c2-01d8-4298-b25d-c677331b5e6d]
+description = "returns the number of grains on the square -> grains on square 2"
+
+[10f45584-2fc3-4875-8ec6-666065d1163b]
+description = "returns the number of grains on the square -> grains on square 3"
+
+[a7cbe01b-36f4-4601-b053-c5f6ae055170]
+description = "returns the number of grains on the square -> grains on square 4"
+
+[c50acc89-8535-44e4-918f-b848ad2817d4]
+description = "returns the number of grains on the square -> grains on square 16"
+
+[acd81b46-c2ad-4951-b848-80d15ed5a04f]
+description = "returns the number of grains on the square -> grains on square 32"
+
+[c73b470a-5efb-4d53-9ac6-c5f6487f227b]
+description = "returns the number of grains on the square -> grains on square 64"
+
+[1d47d832-3e85-4974-9466-5bd35af484e3]
+description = "returns the number of grains on the square -> square 0 is invalid"
+
+[61974483-eeb2-465e-be54-ca5dde366453]
+description = "returns the number of grains on the square -> negative square is invalid"
+
+[a95e4374-f32c-45a7-a10d-ffec475c012f]
+description = "returns the number of grains on the square -> square greater than 64 is invalid"
+
+[6eb07385-3659-4b45-a6be-9dc474222750]
+description = "returns the total number of grains on the board"

exercises/practice/grains/grains-test.red

@@ -0,0 +1,123 @@
+Red [
+	description: {Tests for "Grains" Exercism exercise}
+	author: "loziniak"
+]
+
+#include %testlib.red
+
+ test-init/limit %grains.red 1
+; test-init/limit %.meta/example.red 1						; test example solution
+
+canonical-cases: [#(
+    description: "grains on square 1"
+    input: #(
+        square: 1
+    )
+    expected: 1
+    function: "square"
+    uuid: "9fbde8de-36b2-49de-baf2-cd42d6f28405"
+) #(
+    description: "grains on square 2"
+    input: #(
+        square: 2
+    )
+    expected: 2
+    function: "square"
+    uuid: "ee1f30c2-01d8-4298-b25d-c677331b5e6d"
+) #(
+    description: "grains on square 3"
+    input: #(
+        square: 3
+    )
+    expected: 4
+    function: "square"
+    uuid: "10f45584-2fc3-4875-8ec6-666065d1163b"
+) #(
+    description: "grains on square 4"
+    input: #(
+        square: 4
+    )
+    expected: 8
+    function: "square"
+    uuid: "a7cbe01b-36f4-4601-b053-c5f6ae055170"
+) #(
+    description: "grains on square 16"
+    input: #(
+        square: 16
+    )
+    expected: 32768
+    function: "square"
+    uuid: "c50acc89-8535-44e4-918f-b848ad2817d4"
+) #(
+    description: "grains on square 32"
+    input: #(
+        square: 32
+    )
+    expected: 2147483648.0
+    function: "square"
+    uuid: "acd81b46-c2ad-4951-b848-80d15ed5a04f"
+) #(
+    description: "grains on square 64"
+    input: #(
+        square: 64
+    )
+    expected: 9.223372036854776e18
+    function: "square"
+    uuid: "c73b470a-5efb-4d53-9ac6-c5f6487f227b"
+) #(
+    description: "square 0 is invalid"
+    input: #(
+        square: 0
+    )
+    expected: #(
+        error: "square must be between 1 and 64"
+    )
+    function: "square"
+    uuid: "1d47d832-3e85-4974-9466-5bd35af484e3"
+) #(
+    description: "negative square is invalid"
+    input: #(
+        square: -1
+    )
+    expected: #(
+        error: "square must be between 1 and 64"
+    )
+    function: "square"
+    uuid: "61974483-eeb2-465e-be54-ca5dde366453"
+) #(
+    description: "square greater than 64 is invalid"
+    input: #(
+        square: 65
+    )
+    expected: #(
+        error: "square must be between 1 and 64"
+    )
+    function: "square"
+    uuid: "a95e4374-f32c-45a7-a10d-ffec475c012f"
+) #(
+    description: "returns the total number of grains on the board"
+    input: #()
+    expected: 18446744073709551615
+    function: "total"
+    uuid: "6eb07385-3659-4b45-a6be-9dc474222750"
+)]
+
+
+foreach c-case canonical-cases [
+	expect-code: compose [
+		(to word! c-case/function) (values-of c-case/input)
+	]
+	case-code: reduce
+		either all [
+			map? c-case/expected
+			string? c-case/expected/error
+		] [
+			['expect-error/message quote 'user expect-code c-case/expected/error]
+		] [
+			['expect c-case/expected expect-code]
+		]
+
+	test c-case/description case-code
+]
+
+test-results/print

exercises/practice/grains/grains.red

@@ -0,0 +1,15 @@
+Red [
+	description: {"Grains" exercise solution for exercism platform}
+	author: "" ; you can write your name here, in quotes
+]
+
+square: function [
+	square
+] [
+	cause-error 'user 'message "You need to implement square function."
+]
+
+total: function [] [
+	cause-error 'user 'message "You need to implement total function."
+]
+