Add isogram exercise (#13)

* isogram

* small formatting tweaks

Author: quintuple-mallard

config.json

@@ -101,6 +101,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 4
+      },
+      {
+        "slug": "isogram",
+        "name": "Isogram",
+        "uuid": "cae3e1d4-d352-4a7a-8b5f-dc43712bad98",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
       }
     ]
   },

exercises/practice/isogram/.docs/instructions.md

@@ -0,0 +1,14 @@
+# Instructions
+
+Determine if a word or phrase is an isogram.
+
+An isogram (also known as a "non-pattern word") is a word or phrase without a repeating letter, however spaces and hyphens are allowed to appear multiple times.
+
+Examples of isograms:
+
+- lumberjacks
+- background
+- downstream
+- six-year-old
+
+The word _isograms_, however, is not an isogram, because the s repeats.

exercises/practice/isogram/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "quintuple-mallard"
+  ],
+  "files": {
+    "solution": [
+      "isogram.nu"
+    ],
+    "test": [
+      "tests.nu"
+    ],
+    "example": [
+      ".meta/example.nu"
+    ]
+  },
+  "blurb": "Determine if a word or phrase is an isogram.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Isogram"
+}

exercises/practice/isogram/.meta/example.nu

@@ -0,0 +1,7 @@
+def clean [phrase: string] {
+    $phrase | str downcase | split chars | where $it in 'abcdefghijklmnopqrstuvwxyz'
+}
+export def is_isogram [phrase: string] {
+    let phrase = clean $phrase
+    ($phrase | uniq) == $phrase
+}

exercises/practice/isogram/.meta/tests.toml

@@ -0,0 +1,52 @@
+# 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.
+
+[a0e97d2d-669e-47c7-8134-518a1e2c4555]
+description = "empty string"
+
+[9a001b50-f194-4143-bc29-2af5ec1ef652]
+description = "isogram with only lower case characters"
+
+[8ddb0ca3-276e-4f8b-89da-d95d5bae78a4]
+description = "word with one duplicated character"
+
+[6450b333-cbc2-4b24-a723-0b459b34fe18]
+description = "word with one duplicated character from the end of the alphabet"
+
+[a15ff557-dd04-4764-99e7-02cc1a385863]
+description = "longest reported english isogram"
+
+[f1a7f6c7-a42f-4915-91d7-35b2ea11c92e]
+description = "word with duplicated character in mixed case"
+
+[14a4f3c1-3b47-4695-b645-53d328298942]
+description = "word with duplicated character in mixed case, lowercase first"
+
+[423b850c-7090-4a8a-b057-97f1cadd7c42]
+description = "hypothetical isogrammic word with hyphen"
+
+[93dbeaa0-3c5a-45c2-8b25-428b8eacd4f2]
+description = "hypothetical word with duplicated character following hyphen"
+
+[36b30e5c-173f-49c6-a515-93a3e825553f]
+description = "isogram with duplicated hyphen"
+
+[cdabafa0-c9f4-4c1f-b142-689c6ee17d93]
+description = "made-up name that is an isogram"
+
+[5fc61048-d74e-48fd-bc34-abfc21552d4d]
+description = "duplicated character in the middle"
+
+[310ac53d-8932-47bc-bbb4-b2b94f25a83e]
+description = "same first and last characters"
+
+[0d0b8644-0a1e-4a31-a432-2b3ee270d847]
+description = "word with duplicated character and with two hyphens"

exercises/practice/isogram/isogram.nu

@@ -0,0 +1,3 @@
+export def is_isogram [phrase: string] {
+    error make {msg: "Please implement is_isogram"}
+}

exercises/practice/isogram/tests.nu

@@ -0,0 +1,17 @@
+use isogram.nu is_isogram
+use std/assert
+
+assert equal (is_isogram "") true
+assert equal (is_isogram "isogram") true
+assert equal (is_isogram "eleven") false
+assert equal (is_isogram "zzyzx") false
+assert equal (is_isogram "subdermatoglyphic") true
+assert equal (is_isogram "Alphabet") false
+assert equal (is_isogram "alphAbet") false
+assert equal (is_isogram "thumbscrew-japingly") true
+assert equal (is_isogram "thumbscrew-jappingly") false
+assert equal (is_isogram "six-year-old") true
+assert equal (is_isogram "Emily Jung Schwartzkopf") true
+assert equal (is_isogram "accentor") false
+assert equal (is_isogram "angola") false
+assert equal (is_isogram "up-to-date") false