adding isogram

config.json

@@ -68,6 +68,16 @@
         "Maybe"
       ]
     },
+    {
+      "uuid": "6eba4eac-6665-4ad6-ac21-3651a11ab4b4",
+      "slug": "isogram",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 1,
+      "topics": [
+        "Data.Char"
+      ]
+    },
     {
       "uuid": "85d77b8e-9b87-4d02-9fba-81f843bd66f1",
       "slug": "rna-transcription",

exercises/isogram/README.md

@@ -0,0 +1,72 @@
+# Isogram
+
+Determine if a word or phrase is an isogram.
+
+An isogram (also known as a "nonpattern word") is a word or phrase without a repeating letter.
+
+Examples of isograms:
+
+lumberjacks
+background
+downstream
+The word isograms, however, is not an isogram, because the s repeats.
+
+## Getting Started
+
+For installation and learning resources, refer to the
+[exercism help page](http://exercism.io/languages/haskell).
+
+## Running the tests
+
+To run the test suite, execute the following command:
+
+```bash
+stack test
+```
+
+#### If you get an error message like this...
+
+```
+No .cabal file found in directory
+```
+
+You are probably running an old stack version and need
+to upgrade it.
+
+#### Otherwise, if you get an error message like this...
+
+```
+No compiler found, expected minor version match with...
+Try running "stack setup" to install the correct GHC...
+```
+
+Just do as it says and it will download and install
+the correct compiler version:
+
+```bash
+stack setup
+```
+
+## Running *GHCi*
+
+If you want to play with your solution in GHCi, just run the command:
+
+```bash
+stack ghci
+```
+
+## Feedback, Issues, Pull Requests
+
+The [exercism/haskell](https://github.com/exercism/haskell) repository on
+GitHub is the home for all of the Haskell exercises.
+
+If you have feedback about an exercise, or want to help implementing a new
+one, head over there and create an issue.  We'll do our best to help you!
+
+## Source
+
+see more  at [wikipedia page of isograms]("https://en.wikipedia.org/wiki/Isogram")
+
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

exercises/isogram/examples/success-standard/package.yaml

@@ -0,0 +1,16 @@
+name: isogram
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: Isogram
+  source-dirs: src
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - isogram
+      - hspec

exercises/isogram/examples/success-standard/src/Isogram.hs

@@ -0,0 +1,8 @@
+module Isogram (isIsogram) where
+
+import Data.Char (isLetter, toLower)
+
+isIsogram :: String -> Bool
+isIsogram = fn . map toLower
+  where fn []     = True
+        fn (x:xs) = not (isLetter x && x `elem` xs) && fn xs

exercises/isogram/package.yaml

@@ -0,0 +1,20 @@
+name: isogram
+version: 1.1.0
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: Isogram
+  source-dirs: src
+  dependencies:
+  # - foo       # List here the packages you
+  # - bar       # want to use in your solution.
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - isogram
+      - hspec

exercises/isogram/src/Isogram.hs

@@ -0,0 +1,6 @@
+module Isogram (isIsogram) where
+
+import Data.Char
+
+isIsogram :: String -> Bool
+isIsogram = error "You need to implement this function!"

exercises/isogram/stack.yaml

@@ -0,0 +1 @@
+resolver: lts-8.21

exercises/isogram/test/Tests.hs

@@ -0,0 +1,64 @@
+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
+{-# LANGUAGE RecordWildCards #-}
+
+import Data.Foldable     (for_)
+import Test.Hspec        (Spec, describe, it, shouldBe)
+import Test.Hspec.Runner (configFastFail, defaultConfig, hspecWith)
+
+import Isogram (isIsogram)
+
+main :: IO ()
+main = hspecWith defaultConfig {configFastFail = True} specs
+
+specs :: Spec
+specs = describe "isIsogram" $ for_ cases test
+  where
+
+    test Case{..} = it description assertion
+      where
+        assertion = isIsogram input `shouldBe` expected
+
+
+data Case = Case { description :: String
+                 , input       :: String
+                 , expected    :: Bool
+                 }
+
+cases :: [Case]
+cases = [ Case { description = "empty string"
+               , input      = ""
+               , expected    = True
+               }
+        , Case { description = "isogram with only lower case characters"
+               , input      = "isogram"
+               , expected    = True
+               }
+        , Case { description = "word with one duplicated character"
+               , input      = "eleven"
+               , expected    = False
+               }
+        , Case { description = "longest reported english isogram"
+               , input      = "subdermatoglyphic"
+               , expected    = True
+               }
+        , Case { description = "word with duplicated character in mixed case"
+               , input      = "Alphabet"
+               , expected    = False
+               }
+        , Case { description = "hypothetical isogrammic word with hyphen"
+               , input      = "thumbscrew-japingly"
+               , expected    = True
+               }
+        , Case { description = "isogram with duplicated non letter character"
+               , input      = "Hjelmqvist-Gryb-Zock-Pfund-Wax"
+               , expected    = True
+               }
+        , Case { description = "made-up name that is an isogram"
+               , input      = "Emily Jung Schwartzkopf"
+               , expected    = True
+               }
+        , Case { description = "duplicated character in the middle"
+               , input      = "accentor"
+               , expected    = False
+               }
+        ]