[Haskell-cafe] multi-thread and lazy evaluation

[Brandon Allbery]

On Mon, Dec 24, 2012 at 8:45 AM, Corentin Dupont
<corentin.dupont at gmail.com>wrote:

> *execBlocking :: MVar (Maybe MyData) -> IO ()
> execBlocking mv = do
>    let (a::String) = a
>    --If you uncomment the next line, it will work
>    --putStrLn $ show a
>    putMVar mv (Just $ MyData a "toto")*
>

It's laziness, yes; you need to do something along the lines of

> let a = length a `seq` a

or possibly Control.Exception.evaluate needs to be involved somewhere.

-- 
brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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