Andres Loeh wrote:
[...] We are pleased to announce the first official release of lhs2TeX, a preprocessor to generate LaTeX code from literate Haskell sources.
Thanks for producing such a wonderful and useful tool! I am pleased to report that I managed to get lhs2TeX working on Win32, by modifying just a single byte in the source code. Unfortunately my "one byte patch" is just a short-term non-portable fix, and it's not entirely clear what the right long-term solution is. I thought I'd share my fix for the benefit of brave souls that wish to apply it, and offer some thoughts about what a better long-term solution might be. The Issue --------- Using Cygwin on Win32, one can build and install lhs2TeX by just following the standard build instructions given for building on Unix-like systems: ./configure ; make ; make install However, when you actually run the lhs2TeX binary installed in /usr/local/bin, it will be unable to locate its lhs2TeX.fmt file, even if you attempt to set the LHS2TEX environment variable to point to the directory where this file is installed. There are two reasons for this: 1. GHC does not use Cygwin, and produces executables that do not use the Cygwin library or understand Cygwin-style file paths. So even though "make install" installed lhs2TeX.fmt in /usr/local/share/lhs2TeX, and even though lhs2Tex attempts to open the file "/usr/local/share/lhs2TeX/lhs2TeX.sty", this path ultimately just gets passed on unprocessed to the Win32 file open function (CreateFile). Unfortunately, this is not a valid Win32 path. 2. lhs2TeX includes its own code to look for its needed files on a search path constructed from some combination of a compiled-in list of directories and those constructed from the $LHS2TEX and $HOME environment variables. This code supports both ':' and ';' as path component seperators, probably in an attempt at portability. Unfortunately, this isn't actually the right solution, as it precludes specifying drive letters in paths. A value of "C:/foo/lhs2TeX/" for $LHS2TEX ends up being processed as two directories: "C" and "/foo/lhs2TeX/"! My Quick Fix Workaround: ------------------------ 1. In the lhs2TeX sources, change line 42 of FileNameUtils.lhs from: > environmentSeparators = ";:" to: > environmentSeparators = ";" and do another "make install". 2. Set your LHS2TEX environment variable to a path that reflects where doing "make install" under Cygwin actually installed the lhs2Tex.fmt file. On my system, this is "c:/cygwin/usr/local/share/lhs2tex". Of course, this solution isn't a very good one for the long term, since ':' is the right choice for a path seperator under Unix. Thoughts on a Robust Solution: ------------------------------ As discussed above, we are really being bitten by two seperate issues here. The first is that GHC does not use Cygwin, and the second is that, in the absence of a portable infrastructure for locating files, lhs2TeX implements this itself, in an unfortunately non-portable way. The GHC team put a great deal of effort into making ghc independent of Cygwin, so I won't even bother trying to make the case for ghc just using Cygwin for file I/O (even though I think there is a strong case to be made). Instead, I propose that it would be very valuable if there were some standardized, portable library that Haskell programs like lhs2TeX could use for locating files that should be installed with the program. Ideally, such a library would support some notion of search paths, be configurable through both global and application-specific search path environment variables, and completely isolate the application from operating system-specific path name issues such as ';' vs. ':' and '/' vs. '\'. It's important that this implementation be standardized and shipped with the Haskell compiler, so that the O.S.-dependent path and internal field seperators are defined internally when the Haskell compiler is built for a particular platform, and isn't exposed to applications. This should be pretty straightforward to implement; I'm sorry I can't spare the day or so it would take to contribute this myself right now, but perhaps some enterprising soul on this list will be inspired to take a stab at it. -antony -- Antony Courtney Grad. Student, Dept. of Computer Science, Yale University antony@apocalypse.org http://www.apocalypse.org/pub/u/antony