Add nth-prime (#191)

config.json

@@ -181,6 +181,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "nth-prime",
+        "name": "Nth Prime",
+        "uuid": "2ea97355-acb9-4043-b107-964b6b7a1752",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "pangram",
         "name": "Pangram",

exercises/practice/nth-prime/.docs/instructions.md

@@ -0,0 +1,7 @@
+# Instructions
+
+Given a number n, determine what the nth prime is.
+
+By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
+
+If your language provides methods in the standard library to deal with prime numbers, pretend they don't exist and implement them yourself.

exercises/practice/nth-prime/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "nth-prime.red"
+    ],
+    "test": [
+      "nth-prime-test.red"
+    ],
+    "example": [
+      ".meta/example.red"
+    ]
+  },
+  "blurb": "Given a number n, determine what the nth prime is.",
+  "source": "A variation on Problem 7 at Project Euler",
+  "source_url": "https://projecteuler.net/problem=7"
+}

exercises/practice/nth-prime/.meta/example.red

@@ -0,0 +1,41 @@
+Red [
+	description: {"Nth Prime" exercise solution for exercism platform}
+	author: "BNAndras"
+]
+
+prime: function [
+	number
+] [
+	if number == 0 [
+		cause-error 'user 'message "there is no zeroth prime"
+	]
+
+	if number == 1 [return 2]
+
+
+	tally: 1
+	candidate: 1
+	while [tally < number] [
+		candidate: candidate + 2
+
+		if prime? candidate [
+			tally: tally + 1
+		]
+	]
+	candidate
+]
+
+prime?: function [
+	number
+] [
+	if number <= 1 [return false]
+	if number == 2 [return true]
+	if number % 2 == 0 [return false]
+
+	prime: 3
+	while [prime * prime <= number] [
+		if number % prime == 0 [return false]
+		prime: prime + 2
+	]
+	true
+]

exercises/practice/nth-prime/.meta/tests.toml

@@ -0,0 +1,25 @@
+# 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.
+
+[75c65189-8aef-471a-81de-0a90c728160c]
+description = "first prime"
+
+[2c38804c-295f-4701-b728-56dea34fd1a0]
+description = "second prime"
+
+[56692534-781e-4e8c-b1f9-3e82c1640259]
+description = "sixth prime"
+
+[fce1e979-0edb-412d-93aa-2c744e8f50ff]
+description = "big prime"
+
+[bd0a9eae-6df7-485b-a144-80e13c7d55b2]
+description = "there is no zeroth prime"

exercises/practice/nth-prime/nth-prime-test.red

@@ -0,0 +1,73 @@
+Red [
+	description: {Tests for "Nth Prime" Exercism exercise}
+	author: "loziniak"
+]
+
+#include %testlib.red
+
+test-init/limit %nth-prime.red 1
+; test-init/limit %.meta/example.red 1						; test example solution
+
+canonical-cases: [#[
+    description: "first prime"
+    input: #[
+        number: 1
+    ]
+    expected: 2
+    function: "prime"
+    uuid: "75c65189-8aef-471a-81de-0a90c728160c"
+] #[
+    description: "second prime"
+    input: #[
+        number: 2
+    ]
+    expected: 3
+    function: "prime"
+    uuid: "2c38804c-295f-4701-b728-56dea34fd1a0"
+] #[
+    description: "sixth prime"
+    input: #[
+        number: 6
+    ]
+    expected: 13
+    function: "prime"
+    uuid: "56692534-781e-4e8c-b1f9-3e82c1640259"
+] #[
+    description: "big prime"
+    input: #[
+        number: 10001
+    ]
+    expected: 104743
+    function: "prime"
+    uuid: "fce1e979-0edb-412d-93aa-2c744e8f50ff"
+] #[
+    description: "there is no zeroth prime"
+    input: #[
+        number: 0
+    ]
+    expected: #[
+        error: "there is no zeroth prime"
+    ]
+    function: "prime"
+    uuid: "bd0a9eae-6df7-485b-a144-80e13c7d55b2"
+]]
+
+
+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/nth-prime/nth-prime.red

@@ -0,0 +1,11 @@
+Red [
+	description: {"Nth Prime" exercise solution for exercism platform}
+	author: "" ; you can write your name here, in quotes
+]
+
+prime: function [
+	number
+] [
+	cause-error 'user 'message "You need to implement prime function."
+]
+