-------- Original Message --------
Subject: Re: [Haskell-cafe] "Casting" newtype to base type?
From: Tom Ellis <tom-lists-haskell-cafe-2...@jaguarpaw.co.uk>
To: haskell-cafe@haskell.org
Date: 02.07.2013 15:25
On Tue, Jul 02, 2013 at 03:03:08PM +0200, Vlatko Basic wrote:
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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