Re: [Haskell-cafe] "Casting" newtype to base type?

You could always just put it into your newtype: newtype IOS = IOS { unIOS :: IO String } On Tue, Jul 2, 2013 at 9:31 AM, Vlatko Basic wrote:

-------- Original Message -------- Subject: Re: [Haskell-cafe] "Casting" newtype to base type? From: Tom Ellis To: haskell-cafe@haskell.org Date: 02.07.2013 15:25

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On Tue, Jul 02, 2013 at 03:03:08PM +0200, Vlatko Basic wrote:

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Is there a nicer way to extract the 'IO String' from 'IOS', without 'case' or without pattern matching the whole 'P'?

newtype IOS = IOS (IO String) data P = P { getA :: String, getB :: String, getC :: IOS } deriving (Show, Eq)

getC_IO :: P -> IO String getC_IO p = case getC p of IOS a -> a getC_IO (P _ _ (IOS a)) = a

How about

unIOS :: IOS -> IO String unIOS (IOS a) = a

getC_IO :: P -> IO String getC_IO = unIOS . getC

Thanks for your answer. I had those two funcs, but thought there might be a shorter/prettier one-func one-liner. :-)

...

Tom

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