preemptive getLine on cygwin?
I seem to have some problems understanding preemptive getLine behaviour on cygwin, and wonder whether this is a known/fixed bug/feature (I haven't switched to ghc-6.. yet), or whether anyone has experience with this (behaviour on solaris, with an even older ghc is more or less as expected). Claus -- consider the following example. compile, run, and whenever the -- program waits for input, enter the next natural number, starting -- from 1. note that the program preempts the first input and may -- or may not accept input after the second output.. module Main where import IO main = do hGetBuffering stdin = print hGetLine stdin = print hGetLine stdin = print --- win98, cygwin $ ./Getline LineBuffering 1 1 $ cat | ./Getline BlockBuffering Nothing 1 1 2 2 3 $ ghc --version The Glorious Glasgow Haskell Compilation System, version 5.04.2 --- solaris $ ./GetLine LineBuffering 1 1 2 2 $ cat | ./GetLine BlockBuffering Nothing 1 1 2 2 3 $ ghc --version The Glorious Glasgow Haskell Compilation System, version 5.02.3 ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: preemptive getLine on cygwin?
I seem to have some problems understanding preemptive getLine behaviour on cygwin, and wonder whether this is a known/fixed bug/feature (I haven't switched to ghc-6.. yet), or whether anyone has experience with this (behaviour on solaris, with an even older ghc is more or less as expected). You're running a fairly old version of GHC. With 5.04.3 here I get different behaviour, although strangely it seems that stdin and stdout don't default to LineBuffering in a cygwin shell window. So that's a third variant of runtime behaviour, then, for the same trivial program (probably cygwin on a more modern windows?)!? What do other GHC versions say? And, more importantly, what _should_ they do? Strangely, with Blockbuffering the program seems to be slightly better behaved than with LineBuffering in cygwin, so the cat-hack helps a bit (strangely, because I'm reading lines, so I'd usually explicitly set LineBuffering.., and slightly better, because it's still not quite as I would have expected). I'd still like to understand what's going on and how to get my Haskell programs to behave (this arises in a debugging mode of a larger app and means that, at the moment, I can't easily use this for debugging, which makes life slightly difficult, but at least it doesn't seem to cause the bug*..). Cheers, Claus * just checked in an ms-dos-console, which works as expected. So it seems that the issue is an interaction of ghc/cygwin? Getline LineBuffering 1 1 2 2 ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: preemptive getLine on cygwin?
So that's a third variant of runtime behaviour, then, for the same trivial program (probably cygwin on a more modern windows?)!? What do other GHC versions say? And, more importantly, what _should_ they do? GHC 5.04.3 behaves as I'd expect, except that it defaults to BlockBuffering for stdin/stdout in a cygwin window. In a DOS window it defaults to LineBuffering as expected. This appears to be because mingw's implementation of isatty() only detects DOS windows, which is reasonable. Strangely, with Blockbuffering the program seems to be slightly better behaved than with LineBuffering in cygwin, so the cat-hack helps a bit (strangely, because I'm reading lines, so I'd usually explicitly set LineBuffering.., and slightly better, because it's still not quite as I would have expected). I'd still like to understand what's going on and how to get my Haskell programs to behave (this arises in a debugging mode of a larger app and means that, at the moment, I can't easily use this for debugging, which makes life slightly difficult, but at least it doesn't seem to cause the bug*..). I think just upgrading your GHC should fix things. If not, we'll look into it. Cheers, Simon ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: preemptive getLine on cygwin?
I seem to have some problems understanding preemptive getLine behaviour on cygwin, and wonder whether this is a known/fixed bug/feature (I haven't switched to ghc-6.. yet), or whether anyone has experience with this (behaviour on solaris, with an even older ghc is more or less as expected). You're running a fairly old version of GHC. With 5.04.3 here I get different behaviour, although strangely it seems that stdin and stdout don't default to LineBuffering in a cygwin shell window. Cheers, Simon ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
