I want to switch code on the OS but this always goes through to the #else (on windows or elsewhere): {-# OPTIONS -cpp #-} #ifdef WIN32 main = putStrLn "hello windows" #else main = putStrLn "hello something else" #endif Does this depend on a Makefile setting WIN32, or should there be something predefined? Thanks, -- View this message in context: http://www.nabble.com/How-to-use--ifdef-WIN32-tp14448173p14448173.html Sent from the Haskell - Glasgow-haskell-users mailing list archive at Nabble.com.
Hi Jim
I want to switch code on the OS but this always goes through to the #else (on windows or elsewhere):
{-# OPTIONS -cpp #-} #ifdef WIN32 main = putStrLn "hello windows" #else main = putStrLn "hello something else" #endif
Does this depend on a Makefile setting WIN32, or should there be something predefined?
<answer> #if defined(mingw32_HOST_OS) || defined(__MINGW32__) </answer> <rant> If you want to test for Windows you have to ask whether an unrelated system is installed on your machine. Even if it isn't, you still have to test this value. This is what I call a "bug". You might also want to use System.Info.os and test this value dynamically rather than as a preprocessor, that keeps both code branches type checking and probably isn't much more expensive at runtime. Guess what the value of "os" returns on Windows? (hint: its ill-typed, being not an operating system) </rant> Thanks Neil
Neil Mitchell wrote:
Hi Jim
<answer>
#if defined(mingw32_HOST_OS) || defined(__MINGW32__)
</answer>
Thanks Neil, Jim
<rant>
If you want to test for Windows you have to ask whether an unrelated system is installed on your machine. Even if it isn't, you still have to test this value. This is what I call a "bug".
You might also want to use System.Info.os and test this value dynamically rather than as a preprocessor, that keeps both code branches type checking and probably isn't much more expensive at runtime. Guess what the value of "os" returns on Windows? (hint: its ill-typed, being not an operating system)
</rant>
Thanks
Neil
-- Jim Burton
On Thursday 20 December 2007 18:37:15 Jim Burton wrote:
I want to switch code on the OS but this always goes through to the #else (on windows or elsewhere):
{-# OPTIONS -cpp #-} #ifdef WIN32 main = putStrLn "hello windows" #else main = putStrLn "hello something else" #endif
Does this depend on a Makefile setting WIN32, or should there be something predefined?
Thanks,
If you're using Cabal, something like this should work: if os(win32) cpp-options: -DWIN32 Cheers, Spencer Janssen
On Thursday 20 December 2007 22:04:13 Duncan Coutts wrote:
On Thu, 2007-12-20 at 21:16 -0600, Spencer Janssen wrote:
If you're using Cabal, something like this should work:
if os(win32) cpp-options: -DWIN32
To be precise:
if os(windows) cpp-options: -DWIN32
See, Cabal is (mostly) Neil "I hate mingw" Mitchell compliant. :-)
Duncan
Should example 4 in section 2.1.5 of the Cabal manual be changed, then? Or are win32 and windows equivalent? Spencer Janssen
On Fri, 2007-12-21 at 00:11 -0600, Spencer Janssen wrote:
On Thursday 20 December 2007 22:04:13 Duncan Coutts wrote:
On Thu, 2007-12-20 at 21:16 -0600, Spencer Janssen wrote:
If you're using Cabal, something like this should work:
if os(win32) cpp-options: -DWIN32
To be precise:
if os(windows) cpp-options: -DWIN32
See, Cabal is (mostly) Neil "I hate mingw" Mitchell compliant. :-)
Should example 4 in section 2.1.5 of the Cabal manual be changed, then? Or are win32 and windows equivalent?
Well spotted. Now fixed in darcs. Duncan
participants (4)
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Duncan Coutts -
Jim Burton -
Neil Mitchell -
Spencer Janssen