[Haskell-cafe] Implicit Multi Threading in Switch Case

Yotam Ohad yotam2206 at gmail.com
Tue Jun 20 09:28:15 UTC 2017

After reading "Push-Pull Functional Reactive Programming
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?

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/haskell-cafe/attachments/20170620/6c86a95e/attachment.html>

More information about the Haskell-Cafe mailing list