Re: [Haskell-cafe] preprocessor, how to?

On Mon, Jan 06, 2014 at 09:25:25PM +1300, Chris Wong wrote:

You can use forward slashes in Windows as well.

It's worth clarifying this somewhat I think. I found this at http://is.gd/a5gCuk: Every version of Windows has accepted "/" as a path separator. So has every version of MS-DOS beginning with DOS 2.0 (the first version that had subdirectories). It's only been in command lines that "/" was not allowed, because it had already been used as a switch delimiter in MS-DOS 1.0. So as long as you keep away from stuff like System.Process.system you should be fine with ordinary slashes. /M

On Jan 6, 2014 9:13 PM, "Kees Bleijenberg" wrote:

...

In a program I use a lot of hamlet files. All these hamlet files are in a submap of the source map. In code: allHtml = Mconcat [ $(hamletFile "hamlet\\belastingen.hamlet") renderUrl ,$(hamletFile "hamlet\\winddruk.hamlet") renderUrl .. ,$(hamletFile "hamlet\\berekeningDruk.hamlet") renderUrl ,$(hamletFile "hamlet\\drukNaarBuigTrek.hamlet") renderUrl] This is a Windows program.

For another project I want to use this piece of code on Linux. The code should now be: .. $(hamletFile "hamlet/winddruk.hamlet") renderUrl

I can't use pathSeparator here, because this is all happening at compile time. So I think I need a preprocessor. I would like to have a kind of hamletDir macro and change the code to something like:

#ifdef Win32 hamletDir = "hamlet\\" #else hamletDir = "hamlet/" #endif ... $(hamletFile "{hamletDir}winddruk.hamlet") renderUrl Is it possible in Haskell and how do I it?

All examples of preprocessing in Haskell I found are something like this: #ifdef xxx aaaa #else Bbbbb #endif I could use that. But a user defined macro is less code.

Kees

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