Run-length encoding: Difference between revisions
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(→{{header|Haskell}}: Added a variant expressed in terms of span.) |
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=={{header|Haskell}}== |
=={{header|Haskell}}== |
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=== |
===In terms of group=== |
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<lang haskell>import Data.List (group) |
<lang haskell>import Data.List (group) |
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import Control.Arrow ((&&&)) |
import Control.Arrow ((&&&)) |
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decoded = rldecode encoded |
decoded = rldecode encoded |
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putStrLn $ "Encoded: " ++ show encoded ++ "\nDecoded: " ++ show decoded</lang> |
putStrLn $ "Encoded: " ++ show encoded ++ "\nDecoded: " ++ show decoded</lang> |
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===Version 2=== |
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Or: |
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<lang Haskell> |
<lang Haskell> |
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import Data.List |
import Data.List |
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test: text == decode => True |
test: text == decode => True |
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</pre> |
</pre> |
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===In terms of span=== |
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<lang haskell>import Data.Char (isDigit) |
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import Data.List (span) |
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encode :: String -> String |
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encode [] = [] |
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encode (x : xs) = x : (show . succ . length) run <> encode rest |
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where |
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(run, rest) = span (x ==) xs |
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decode [] = [] |
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decode (x : xs) = replicate n x <> decode rest |
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where |
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(ds, rest) = span isDigit xs |
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n = read ds :: Int |
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main :: IO () |
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main = |
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putStrLn encoded |
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>> putStrLn decoded |
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>> print (src == decoded) |
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where |
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src = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW" |
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encoded = encode src |
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decoded = decode encoded</lang> |
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{{Out}} |
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<pre>W12B1W12B3W24B1W14 |
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WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW |
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True</pre> |
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=={{header|Icon}} and {{header|Unicon}}== |
=={{header|Icon}} and {{header|Unicon}}== |
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