Re: [Haskell-cafe] Implicit Multi Threading in Switch Case

I don't think you're going to be able to achieve this with pattern matches. What may be useful is some of the stuff in the package unamb https://hackage.haskell.org/package/unamb-0.2.5. On Tue, Jun 20, 2017 at 8:10 PM, Isaac Elliott wrote:

Hey Yotam,

Pattern matching clauses evaluate from left to right. You can get the behavour you're after by swapping the arguments in the tuple:

case (stop, infi) of (Just _, Nothing) -> 1 (_, _) -> 2

Evaluates to 2

On Tue, 20 Jun. 2017, 7:29 pm Yotam Ohad, wrote:

...

Hi, After reading "Push-Pull Functional Reactive Programming https://pdfs.semanticscholar.org/fb7a/879d639641341e025197b40afad9e21f0ce5.p..." I had an idea about deciding which, of two events, comes first. Instead of using forkIO, I tried something like the following:

infi :: Maybe Int infi = infi

stop :: Maybe Int stop = Nothing

test :: Int test = case (infi, stop) of (Nothing, Just _) -> 1 (_, _) -> 2

Here, infi is an action that never ends, and stop a function that ends immediately. I thought that the compiler would see that stop evaluates immediately to Nothing and thus will return 2, but it tries to evaluate infi and get stuck.

I think it happens because I am using a tuple to hold both values (but not really sure about it). Do you know a way to make this arrangement work?

Yotam _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.

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