Concurrent Haskell
Andre W B Furtado
aw@free.elogica.com.br
Mon, 16 Apr 2001 20:36:30 -0300
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I am trying to create a program that prints interleaved sequences of =
'a's and 'z's, using Haskell Direct (under GHC). I've tryied the =
following:
import Concurrent
main :: IO()
main =3D let loop ch =3D putStr(ch) >> loop ch in
forkIO (loop "a") >> loop "z"
But this program prints only 'z's, and no 'a's. I was surprised by this, =
since GHC uses preemptive multitasking, not cooperative multitasking. =
Does anyone knows what's going wrong?
Thanks,
Andre W b Furtado
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<DIV><FONT face=3DArial size=3D2>I am trying to create a program that =
prints=20
interleaved sequences of 'a's and 'z's, using Haskell Direct =
(under=20
GHC). I've tryied the following:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>import Concurrent</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>main :: IO()<BR>main =3D let loop ch =
=3D putStr(ch)=20
>> loop ch in<BR> forkIO (loop =
"a")=20
>> loop "z"</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>But this program prints only 'z's, and =
no=20
'a's. I was surprised by this, since GHC uses preemptive =
multitasking, not=20
cooperative multitasking. Does anyone knows what's going =
wrong?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Andre W b =
Furtado</FONT></DIV></BODY></HTML>
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