Add hamming (#120)

* Add hamming

* Format hamming config

config.json

@@ -114,6 +114,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "hamming",
+        "name": "Hamming",
+        "uuid": "5d525867-c31c-468e-9b25-87b5ba93a1da",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "square-root",
         "name": "Square Root",

exercises/practice/hamming/.docs/instructions.md

@@ -0,0 +1,27 @@
+# Instructions
+
+Calculate the Hamming Distance between two DNA strands.
+
+Your body is made up of cells that contain DNA.
+Those cells regularly wear out and need replacing, which they achieve by dividing into daughter cells.
+In fact, the average human body experiences about 10 quadrillion cell divisions in a lifetime!
+
+When cells divide, their DNA replicates too.
+Sometimes during this process mistakes happen and single pieces of DNA get encoded with the incorrect information.
+If we compare two strands of DNA and count the differences between them we can see how many mistakes occurred.
+This is known as the "Hamming Distance".
+
+We read DNA using the letters C,A,G and T.
+Two strands might look like this:
+
+    GAGCCTACTAACGGGAT
+    CATCGTAATGACGGCCT
+    ^ ^ ^  ^ ^    ^^
+
+They have 7 differences, and therefore the Hamming Distance is 7.
+
+The Hamming Distance is useful for lots of things in science, not just biology, so it's a nice phrase to be familiar with :)
+
+## Implementation notes
+
+The Hamming distance is only defined for sequences of equal length, so an attempt to calculate it between sequences of different lengths should not work.

exercises/practice/hamming/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "hamming.red"
+    ],
+    "test": [
+      "hamming-test.red"
+    ],
+    "example": [
+      ".meta/example.red"
+    ]
+  },
+  "blurb": "Calculate the Hamming difference between two DNA strands.",
+  "source": "The Calculating Point Mutations problem at Rosalind",
+  "source_url": "https://rosalind.info/problems/hamm/"
+}

exercises/practice/hamming/.meta/example.red

@@ -0,0 +1,26 @@
+Red [
+	description: {"Hamming" exercise solution for exercism platform}
+	author: "BNAndras"
+]
+
+distance: function [
+	strand1
+	strand2
+] [
+	count: 0
+	if (length? strand1) <> (length? strand2) [
+		cause-error 'user 'message "strands must be of equal length"
+	]
+
+	i: 0
+	while [i <= length? strand1] [
+		if (pick strand1 i) <> (pick strand2 i) [
+			count: count + 1
+		]
+
+		i: i + 1
+	]
+
+	count
+]
+

exercises/practice/hamming/.meta/tests.toml

@@ -0,0 +1,67 @@
+# 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.
+
+[f6dcb64f-03b0-4b60-81b1-3c9dbf47e887]
+description = "empty strands"
+
+[54681314-eee2-439a-9db0-b0636c656156]
+description = "single letter identical strands"
+
+[294479a3-a4c8-478f-8d63-6209815a827b]
+description = "single letter different strands"
+
+[9aed5f34-5693-4344-9b31-40c692fb5592]
+description = "long identical strands"
+
+[cd2273a5-c576-46c8-a52b-dee251c3e6e5]
+description = "long different strands"
+
+[919f8ef0-b767-4d1b-8516-6379d07fcb28]
+description = "disallow first strand longer"
+include = false
+
+[b9228bb1-465f-4141-b40f-1f99812de5a8]
+description = "disallow first strand longer"
+reimplements = "919f8ef0-b767-4d1b-8516-6379d07fcb28"
+
+[8a2d4ed0-ead5-4fdd-924d-27c4cf56e60e]
+description = "disallow second strand longer"
+include = false
+
+[dab38838-26bb-4fff-acbe-3b0a9bfeba2d]
+description = "disallow second strand longer"
+reimplements = "8a2d4ed0-ead5-4fdd-924d-27c4cf56e60e"
+
+[5dce058b-28d4-4ca7-aa64-adfe4e17784c]
+description = "disallow left empty strand"
+include = false
+
+[db92e77e-7c72-499d-8fe6-9354d2bfd504]
+description = "disallow left empty strand"
+include = false
+reimplements = "5dce058b-28d4-4ca7-aa64-adfe4e17784c"
+
+[b764d47c-83ff-4de2-ab10-6cfe4b15c0f3]
+description = "disallow empty first strand"
+reimplements = "db92e77e-7c72-499d-8fe6-9354d2bfd504"
+
+[38826d4b-16fb-4639-ac3e-ba027dec8b5f]
+description = "disallow right empty strand"
+include = false
+
+[920cd6e3-18f4-4143-b6b8-74270bb8f8a3]
+description = "disallow right empty strand"
+include = false
+reimplements = "38826d4b-16fb-4639-ac3e-ba027dec8b5f"
+
+[9ab9262f-3521-4191-81f5-0ed184a5aa89]
+description = "disallow empty second strand"
+reimplements = "920cd6e3-18f4-4143-b6b8-74270bb8f8a3"

exercises/practice/hamming/hamming-test.red

@@ -0,0 +1,120 @@
+Red [
+	description: {Tests for "Hamming" Exercism exercise}
+	author: "loziniak"
+]
+
+#include %testlib.red
+
+test-init/limit %hamming.red 1
+; test-init/limit %.meta/example.red 1						; test example solution
+
+canonical-cases: [#(
+    description: "empty strands"
+    input: #(
+        strand1: ""
+        strand2: ""
+    )
+    expected: 0
+    function: "distance"
+    uuid: "f6dcb64f-03b0-4b60-81b1-3c9dbf47e887"
+) #(
+    description: "single letter identical strands"
+    input: #(
+        strand1: "A"
+        strand2: "A"
+    )
+    expected: 0
+    function: "distance"
+    uuid: "54681314-eee2-439a-9db0-b0636c656156"
+) #(
+    description: "single letter different strands"
+    input: #(
+        strand1: "G"
+        strand2: "T"
+    )
+    expected: 1
+    function: "distance"
+    uuid: "294479a3-a4c8-478f-8d63-6209815a827b"
+) #(
+    description: "long identical strands"
+    input: #(
+        strand1: "GGACTGAAATCTG"
+        strand2: "GGACTGAAATCTG"
+    )
+    expected: 0
+    function: "distance"
+    uuid: "9aed5f34-5693-4344-9b31-40c692fb5592"
+) #(
+    description: "long different strands"
+    input: #(
+        strand1: "GGACGGATTCTG"
+        strand2: "AGGACGGATTCT"
+    )
+    expected: 9
+    function: "distance"
+    uuid: "cd2273a5-c576-46c8-a52b-dee251c3e6e5"
+) #(
+    description: "disallow first strand longer"
+    input: #(
+        strand1: "AATG"
+        strand2: "AAA"
+    )
+    expected: #(
+        error: "strands must be of equal length"
+    )
+    function: "distance"
+    uuid: "b9228bb1-465f-4141-b40f-1f99812de5a8"
+) #(
+    description: "disallow second strand longer"
+    input: #(
+        strand1: "ATA"
+        strand2: "AGTG"
+    )
+    expected: #(
+        error: "strands must be of equal length"
+    )
+    function: "distance"
+    uuid: "dab38838-26bb-4fff-acbe-3b0a9bfeba2d"
+) #(
+    description: "disallow empty first strand"
+    input: #(
+        strand1: ""
+        strand2: "G"
+    )
+    expected: #(
+        error: "strands must be of equal length"
+    )
+    function: "distance"
+    uuid: "b764d47c-83ff-4de2-ab10-6cfe4b15c0f3"
+) #(
+    description: "disallow empty second strand"
+    input: #(
+        strand1: "G"
+        strand2: ""
+    )
+    expected: #(
+        error: "strands must be of equal length"
+    )
+    function: "distance"
+    uuid: "9ab9262f-3521-4191-81f5-0ed184a5aa89"
+)]
+
+
+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/hamming/hamming.red

@@ -0,0 +1,12 @@
+Red [
+	description: {"Hamming" exercise solution for exercism platform}
+	author: "" ; you can write your name here, in quotes
+]
+
+distance: function [
+	strand1
+	strand2
+] [
+	cause-error 'user 'message "You need to implement distance function."
+]
+