38 lines
911 B
Haskell
38 lines
911 B
Haskell
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module Shortener.Generator
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( wordID
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, hashID
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, Word
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, Url
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) where
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import Control.Applicative
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import Control.Monad.State
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import System.Random
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import Crypto.Hash.SHA256 (hash)
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import Data.Binary (decode)
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import Data.ByteString.Char8 (pack)
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import Data.ByteString.Lazy (fromStrict)
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type Word = String
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type Url = String
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-- Choose a random element of a list
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choice :: [a] -> State StdGen a
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choice xs = (xs !!) <$> randomSt (0, length xs - 1)
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where randomSt = state . randomR
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-- Generate a random phonetic string
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word :: State StdGen Word
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word = replicateM 10 letter where
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vowels = "aeiou"
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consonants = "bcdfghjklmnpqrstvwxyz"
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letter = choice [vowels, consonants] >>= choice
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-- SHA256 hash to seed a generator
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hashID :: Url -> Int
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hashID = decode . fromStrict . hash . pack
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-- Assing a unique word to the url
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wordID :: Url -> Word
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wordID = evalState word . mkStdGen . hashID
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