File extension is in extensions list: Difference between revisions
→{{header|Haskell}}: Added a version using isSuffixOf (and avoiding the gzip false positive of the draft above)
(→{{header|Haskell}}: Added a version using isSuffixOf (and avoiding the gzip false positive of the draft above)) |
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Line 858:
MyData_v1.0.tar.bz2 True
MyData_v1.0.bz2 False</pre>
We can also express this directly in terms of the '''isSuffix''' function, taking care not to reproduce the small glitch in the draft above, which shows a false positive for '''zip''' in '''.gzip''' (see task description bullet 2).
<lang haskell>import Data.List (find, isSuffixOf)
import Data.Maybe (fromMaybe)
import Data.Char (toLower)
extensionFound :: String -> [String] -> Maybe String
extensionFound fp xs = find (`isSuffixOf` fp) (('.' :) <$> xs) >>= Just
-- TESTS --------------------------------------------------
main :: IO ()
main = do
let w = maximum $ length <$> files
(putStrLn . unlines) $
zipWith
(\fp mb -> rjust w ' ' fp ++ " -> " ++ fromMaybe "n/a" mb)
files
((`extensionFound` lcased extensions) <$> lcased files)
-- DATA ---------------------------------------------------
extensions, files :: [String]
extensions = ["zip", "rar", "7z", "gz", "archive", "A##", "tar.bz2"]
files =
[ "MyData.a##"
, "MyData.tar.Gz"
, "MyData.gzip"
, "MyData.7z.backup"
, "MyData..."
, "MyData"
, "MyData_v1.0.tar.bz2"
, "MyData_v1.0.bz2"
]
-- STRINGS ------------------------------------------------
rjust :: Int -> Char -> String -> String
rjust n c = (drop . length) <*> (replicate n c ++)
lcased :: [String] -> [String]
lcased = fmap (fmap toLower)</lang>
{{Out}}
<pre> MyData.a## -> .a##
MyData.tar.Gz -> .gz
MyData.gzip -> n/a
MyData.7z.backup -> n/a
MyData... -> n/a
MyData -> n/a
MyData_v1.0.tar.bz2 -> .tar.bz2
MyData_v1.0.bz2 -> n/a</pre>
=={{header|J}}==
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