On Wednesday 18 August 2010 11:14:06 am Ertugrul Soeylemez wrote:
loop, loop' :: IO ()
loop = loop
loop' = putStr c loop'
Huh?! Let's translate them. 'loop' becomes:
undefined
But 'loop\'' becomes:
\w0 - let (w1, ()) = putStr c w0
in loop w1
On 08/18/10 11:30, Dan Doel wrote:
Now, moving to the two loops:
loop = loop
loop' = \w0 - let (w1, ()) = putStr c w0 in loop' w1
How are we to distinguish between these? I know of exactly one Haskell
function that can do so: seq. And this is only because it can distinguish
bottom
On 08/18/10 11:30, Dan Doel wrote:
By contrast, here:
http://code.haskell.org/~dolio/agda-share/html/IOE.html
is a term model of IO. It's in Agda, for some proofs, but it's easily done in
GHC. And if we write the above loops in this model, we get:
loop = loop ==
On 08/18/10 12:04, Gregory Crosswhite wrote:
Now we have that loop' = loop''.
Oops! I meant that loop' = loop'' in the world passing model, so that if
loop' = \w0 - let (w1, ()) = putStr c w0 in loop' w1
loop'' = \w0 - let (w1, ()) = putStr c w1 in loop' w1
then loop' = loop''
On Wednesday 18 August 2010 2:50:00 pm Gregory Crosswhite wrote:
On 08/18/10 11:30, Dan Doel wrote:
Now, moving to the two loops:
loop = loop
loop' = \w0 - let (w1, ()) = putStr c w0 in loop' w1
How are we to distinguish between these? I know of exactly one Haskell
function that
On Sat, Aug 14, 2010 at 10:11 PM, Bill Atkins watk...@alum.rpi.edu wrote:
On Saturday Aug 14, 2010, at 12:50 AM, Conal Elliott wrote:
And the IO monad is what Jerzy asked about. I'm pointing out that the
state monad does not capture concurrency, and the EDSL model does not
capture FFI.
Ertugrul Soeylemez wrote:
let (x, world1) = getLine world0
world2 = print (x+1) world1
If between 'getLine' and 'print' something was done by a
concurrent thread, then that change to the world is captured by 'print'.
But in a world passing interpretation of IO, print is supposed to be
Bulat Ziganshin wrote:
But in a world passing interpretation of IO, print is supposed to be a
pure Haskell function. So the value world2 can only depend on the values
of print and world1, but not on the actions of some concurrent thread.
the whole World includes any concurrent thread though ;)
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On 8/15/10 11:40 , Tillmann Rendel wrote:
But in a world passing interpretation of IO, print is supposed to be a pure
Haskell function. So the value world2 can only depend on the values of print
and world1, but not on the actions of some concurrent
Brandon S Allbery KF8NH wrote:
I am confused by this discussion. I originally thought some time back that
IO was about world passing, but in fact it's just handing off a baton to
insure that a particular sequence of IO functions is executed in the
specified sequence and not reordered. Nothing
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On 8/15/10 13:27 , Tillmann Rendel wrote:
Brandon S Allbery KF8NH wrote:
I am confused by this discussion. I originally thought some time back that
IO was about world passing, but in fact it's just handing off a baton to
insure that a particular
On Sunday, August 15, 2010, Tillmann Rendel
ren...@mathematik.uni-marburg.de wrote:
Bulat Ziganshin wrote:
But in a world passing interpretation of IO, print is supposed to be a
pure Haskell function. So the value world2 can only depend on the values
of print and world1, but not on the
Brandon S Allbery KF8NH wrote:
only ordering of calls in the *current*
thread of execution. (Which, hmm, implies that unsafePerformIO and
unsafeInterleaveIO are conceptually similar to forkIO.)
Implementationally they are very similar (at least as far as the baton
is concerned). How hard we
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On 08/15/2010 08:32 PM, wren ng thornton wrote:
Brandon S Allbery KF8NH wrote:
only ordering of calls in the *current*
thread of execution. (Which, hmm, implies that unsafePerformIO and
unsafeInterleaveIO are conceptually similar to forkIO.)
On Saturday Aug 14, 2010, at 12:50 AM, Conal Elliott wrote:
And the IO monad is what Jerzy asked about. I'm pointing out that the state
monad does not capture concurrency, and the EDSL model does not capture
FFI. (Really, it depends which EDSL model. I haven't seen one that can
capture
There are various models. One (the state monad model) of them would
desugar this to:
\world0 -
let (x, world1) = getLine world0
world2 = print (x+1) world1
world3 = print (x+2) world2
in world3
Hi Ertugrul,
This state monad model does not really work for IO, since it
On Sat, Aug 14, 2010 at 9:27 AM, Ertugrul Soeylemez e...@ertes.de wrote:
Conal Elliott co...@conal.net wrote:
There are various models. One (the state monad model) of them would
desugar this to:
\world0 -
let (x, world1) = getLine world0
world2 = print (x+1) world1
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