haskell/atbash cipher

haskell/atbash-cipher/.solution.json

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+{"track":"haskell","exercise":"atbash-cipher","id":"846f79ab13c14f37a17b4f882ffc9486","url":"https://exercism.io/my/solutions/846f79ab13c14f37a17b4f882ffc9486","handle":"Vourhey","is_requester":true,"auto_approve":false}

haskell/atbash-cipher/README.md

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+# Atbash Cipher
+
+Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.
+
+The Atbash cipher is a simple substitution cipher that relies on
+transposing all the letters in the alphabet such that the resulting
+alphabet is backwards. The first letter is replaced with the last
+letter, the second with the second-last, and so on.
+
+An Atbash cipher for the Latin alphabet would be as follows:
+
+```text
+Plain:  abcdefghijklmnopqrstuvwxyz
+Cipher: zyxwvutsrqponmlkjihgfedcba
+```
+
+It is a very weak cipher because it only has one possible key, and it is
+a simple monoalphabetic substitution cipher. However, this may not have
+been an issue in the cipher's time.
+
+Ciphertext is written out in groups of fixed length, the traditional group size
+being 5 letters, and punctuation is excluded. This is to make it harder to guess
+things based on word boundaries.
+
+## Examples
+
+- Encoding `test` gives `gvhg`
+- Decoding `gvhg` gives `test`
+- Decoding `gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt` gives `thequickbrownfoxjumpsoverthelazydog`
+
+
+## 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
+
+Wikipedia [http://en.wikipedia.org/wiki/Atbash](http://en.wikipedia.org/wiki/Atbash)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

haskell/atbash-cipher/atbash-cipher.cabal

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+-- This file has been generated from package.yaml by hpack version 0.28.2.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: f6a46eb0c467f98162e18a6f5b8787fabfb5c5ffb5e4e8faad6f7e904e5315ee
+
+name:           atbash-cipher
+version:        1.1.0.4
+build-type:     Simple
+cabal-version:  >= 1.10
+
+library
+  exposed-modules:
+      Atbash
+  other-modules:
+      Paths_atbash_cipher
+  hs-source-dirs:
+      src
+  build-depends:
+      base
+    , split
+  default-language: Haskell2010
+
+test-suite test
+  type: exitcode-stdio-1.0
+  main-is: Tests.hs
+  other-modules:
+      Paths_atbash_cipher
+  hs-source-dirs:
+      test
+  build-depends:
+      atbash-cipher
+    , base
+    , hspec
+  default-language: Haskell2010

haskell/atbash-cipher/package.yaml

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+name: atbash-cipher
+version: 1.1.0.4
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: Atbash
+  source-dirs: src
+  dependencies:
+   - split
+  # - bar       # want to use in your solution.
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - atbash-cipher
+      - hspec

haskell/atbash-cipher/src/Atbash.hs

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+module Atbash (decode, encode) where
+
+import Data.Char (isAlphaNum, isAlpha, ord, chr, toLower)
+import Data.List.Split (chunksOf)
+
+lettera = ord 'a'
+boundary = lettera + 25
+
+doCipher :: String -> String
+doCipher []     = []
+doCipher (x:xs) = if isAlpha x then
+                    chr (boundary - ord x + lettera) : doCipher xs
+                  else
+                    x : doCipher xs
+
+prepareText :: String -> String
+prepareText text = map toLower $ filter isAlphaNum text
+
+decode :: String -> String
+decode cipherText = doCipher $ prepareText cipherText
+
+encode :: String -> String
+encode plainText = unwords $ 
+                    chunksOf 5 $ 
+                        doCipher (prepareText plainText)

haskell/atbash-cipher/stack.yaml

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+resolver: lts-11.1

haskell/atbash-cipher/test/Tests.hs

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+{-# LANGUAGE RecordWildCards #-}
+
+import Data.Foldable     (for_)
+import Test.Hspec        (Spec, describe, it, shouldBe)
+import Test.Hspec.Runner (configFastFail, defaultConfig, hspecWith)
+
+import Atbash (encode, decode)
+
+main :: IO ()
+main = hspecWith defaultConfig {configFastFail = True} specs
+
+specs :: Spec
+specs = do
+          describe "encode" $ for_ encodeCases $ test encode
+          describe "decode" $ for_ decodeCases $ test decode
+  where
+    test f Case{..} = it description $ f phrase `shouldBe` expected
+
+data Case = Case { description :: String
+                 , phrase      :: String
+                 , expected    :: String
+                 }
+
+encodeCases :: [Case]
+encodeCases =
+    [ Case { description = "encode yes"
+           , phrase      = "yes"
+           , expected    = "bvh"
+           }
+    , Case { description = "encode no"
+           , phrase      = "no"
+           , expected    = "ml"
+           }
+    , Case { description = "encode OMG"
+           , phrase      = "OMG"
+           , expected    = "lnt"
+           }
+    , Case { description = "encode spaces"
+           , phrase      = "O M G"
+           , expected    = "lnt"
+           }
+    , Case { description = "encode mindblowingly"
+           , phrase      = "mindblowingly"
+           , expected    = "nrmwy oldrm tob"
+           }
+    , Case { description = "encode numbers"
+           , phrase      = "Testing,1 2 3, testing."
+           , expected    = "gvhgr mt123 gvhgr mt"
+           }
+    , Case { description = "encode deep thought"
+           , phrase      = "Truth is fiction."
+           , expected    = "gifgs rhurx grlm"
+           }
+    , Case { description = "encode all the letters"
+           , phrase      = "The quick brown fox jumps over the lazy dog."
+           , expected    = "gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt"
+           }
+    ]
+
+decodeCases :: [Case]
+decodeCases =
+    [ Case { description = "decode exercism"
+           , phrase      = "vcvix rhn"
+           , expected    = "exercism"
+           }
+    , Case { description = "decode a sentence"
+           , phrase      = "zmlyh gzxov rhlug vmzhg vkkrm thglm v"
+           , expected    = "anobstacleisoftenasteppingstone"
+           }
+    , Case { description = "decode numbers"
+           , phrase      = "gvhgr mt123 gvhgr mt"
+           , expected    = "testing123testing"
+           }
+    , Case { description = "decode all the letters"
+           , phrase      = "gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt"
+           , expected    = "thequickbrownfoxjumpsoverthelazydog"
+           }
+    ]