Version~2.09

Table of Contents

• 1 Getting the Glasgow `fptools' suite
• 2 Things to check before you start typing
• 3 What machines the Glasgow tools run on
  • 3.1 What platforms the Haskell compiler (GHC) runs on
  • 3.2 What machines the other tools run on
• 4 Installing from binary distributions
  • 4.1 Bundle structure
  • 4.2 Installing
  • 4.3 What bundles there are
  • 4.4 Test that GHC seems to be working
• 5 Installing pre-supposed utilities
• 6 Building from source
  • 6.1 Your source tree
  • 6.2 Build trees
  • 6.3 Getting the build you want
  • 6.4 The story so far
  • 6.5 Making things
  • 6.6 Standard targets
  • 6.7 Other targets
• 7 The `Makefile' architecture
  • 7.1 A small project
  • 7.2 A larger project
  • 7.3 Boilerplate architecture
  • 7.4 The main `mk/boilerplate.mk' file
  • 7.5 Pattern rules and options
  • 7.6 The main `mk/target.mk' file
  • 7.7 Recursion
  • 7.8 Way management
  • 7.9 When the canned rule isn't right
• 8 Booting/porting from C (`.hc') files
• 9 Known pitfalls in building Glasgow Haskell
• 10 Index

1 Getting the Glasgow `fptools' suite

Building the Glasgow tools can be complicated, mostly because there are so many permutations of what/why/how, e.g., "Build Happy with HBC, everything else with GHC, leave out profiling, and test it all on the `real' NoFib programs." Yeeps!

Happily, such complications don't apply to most people. A few common "strategies" serve most purposes. Pick one and proceed as suggested:

Binary distribution.

If your only purpose is to install some of the `fptools' suite then the easiest thing to do is to get a binary distribution. In the binary distribution everything is pre-compiled for your particular machine architecture and operating system, so all you should have to do is install the binaries and libraries in suitable places. Section 4 Installing from binary distributions describes how to do this. A binary distribution may not work for you for two reasons. First, we may not have built the suite for the particular architecture/OS platform you want. That may be due to lack of time and energy (in which case you can get a source distribution and build from it; see below). Alternatively, it may be because we haven't yet ported the suite to your architecture, in which case you are considerably worse off. The second reason a binary distribution may not be what you want is if you want to read or modify the souce code.

Source distribution.

You have a supported platform, but (a) you like the warm fuzzy feeling of compiling things yourself; (b) you want to build something "extra" -- e.g., a set of libraries with strictness-analysis turned off; or (c) you want to hack on GHC yourself. A source distribution contains complete sources for the `fptools' suite. Not only that, but the more awkward machine-independent steps are done for you. For example, if you don't have `flex' you'll find it convenient that the source distribution contains the result of running `flex' on the lexical analyser specification. If you don't want to alter the lexical analyser then this saves you having to find and install `flex'. You will still need a working version of GHC on your machine in order to compile (most of) the sources, however. We make source distributions more frequently than binary distributions; a release that comes with pre-compiled binaries is considered a major release, i.e., a release that we have some confidence will work well by having tested it (more) thoroughly. Source-only distributions are either bugfix releases or snapshots of current state of development. The release has undergone some testing. Source releases of 2.0x can be compiled up using 2.07 (or subsequent bugfix releases) or the Good Old Compiler, GHC 0.29. Compiling with 0.29 is recommended if you're a performance junkie, as 0.29 (still) generates zippier code, but GHC 2.0x is catching up.

Build GHC from intermediate C `.hc' files:

You need a working GHC to use a source distribution. What if you don't have a working GHC? Then you have no choice but to "bootstrap" up from the intermediate C (`.hc') files that we provide. Building GHC on an unsupported platform falls into this category. Please see section 8 Booting/porting from C (`.hc') files. Once you have built GHC, you can build the other Glasgow tools with it. In theory, you can (could?) build GHC with another Haskell compiler (e.g., HBC). We haven't tried to do this for ages and it almost certainly doesn't work any more (for tedious reasons).

The CVS repository.

We make source distributions slightly more often than binary distributions; but still infrequently. If you want more up-to-the minute (but less tested) source code then you need to get access to our CVS repository. All the `fptools' source code is held in a CVS repository. CVS is a pretty good source-code control system, and best of all it works over the network. The repository holds source code only. It holds no mechanically generated files at all. So if you check out a source tree from CVS you will need to install every utility so that you can build all the derived files from scratch. Giving you access to the repository entails some systems administration at our end; and we are a bit nervous about being submerged in bug reports about our current working copy (which is, by definition, in flux). So we are a bit cautious about offering CVS access. Feel free to ask though!

If you are going to do any building from sources (either from a source distribution or the CVS repository) then you need to read all of this manual in detail.

2 Things to check before you start typing

Here's a list of things to check before you get started.

1. Disk space needed: About 30MB (five hamburgers' worth) of disk space for the most basic binary distribution of GHC; more for some platforms, e.g., Alphas. An extra "bundle" (e.g., concurrent Haskell libraries) might take you to 8--10 hamburgers. You'll need over 100MB (say, 20 hamburgers' worth) if you need to build the basic stuff from scratch. All of the above are estimates of disk-space needs.(I don't yet know the disk requirements for the non-GHC tools).

2. Use an appropriate machine, compilers, and things. SPARC boxes, DEC Alphas running OSF/1, and PCs running Linux, FreeBSD, or Solaris are all fully supported. MIPS, AIX, Win32 and HP boxes are in pretty good shape. Section 3 What machines the Glasgow tools run on gives the full run-down on ports or lack thereof.

3. Be sure that the "pre-supposed" utilities are installed. Section 5 Installing pre-supposed utilities elaborates.

4. If you have any problem when building or installing the Glasgow tools, please check the "known pitfalls" (section 9 Known pitfalls in building Glasgow Haskell). Also check the "known bugs" web page for GHC: @begin{center} `http://www.dcs.gla.ac.uk/fp/software/ghc/ghc-bugs.html' @end{center} If you feel there is still some shortcoming in our procedure or instructions, please report it. For GHC, please see the bug-reporting section of the User's guide (separate document), to maximise the usefulness of your report. If in doubt, please send a message to `glasgow-haskell-bugs@dcs.gla.ac.uk'.

3 What machines the Glasgow tools run on

The main question is whether or not the Haskell compiler (GHC) runs on your platform.

A "platform" is a architecture/manufacturer/operating-system combination, such as `sparc-sun-solaris2'. Other common ones are `alpha-dec-osf2', `hppa1.1-hp-hpux9', `i386-unknown-linux', `i386-unknown-solaris2', `i386-unknown-freebsd', `i386-unknown-cygwin32', `m68k-sun-sunos4', `mips-sgi-irix5', `sparc-sun-sunos4', `sparc-sun-solaris2', `powerpc-ibm-aix'.

Bear in mind that certain "bundles", e.g. parallel Haskell, may not work on all machines for which basic Haskell compiling is supported.

Some libraries may only work on a limited number of platforms; for example, a sockets library is of no use unless the operating system supports the underlying BSDisms.

• installing_3.1: What platforms the Haskell compiler (GHC) runs on.
• installing_3.2: What machines the other tools run on.

3.1 What platforms the Haskell compiler (GHC) runs on

The GHC hierarchy of Porting Goodness: (a) Best is a native-code generator; (b) next best is a "registerised" port; (c) the bare minimum is an "unregisterised" port. ("Unregisterised" is so terrible that we won't say more about it).

We use Sun4s running SunOS 4.1.3 and Solaris 2.5, and DEC Alphas running OSF/1 V2.0, so those are the "fully-supported" platforms, unsurprisingly. Both have native-code generators, for quicker compilations. The native-code generator for iX86 platforms (e.g., Linux ELF) is nearly working; but is not turned on by default.

Here's everything that's known about GHC ports. We identify platforms by their "canonical" CPU/Manufacturer/OS triple.

Note that some ports are fussy about which GCC version you use; or require GAS; or ...

`alpha-dec-osf1':

(We have OSF/1 V2.0.) Fully supported, including native-code generator. We recommend GCC 2.6.x or later.

`sparc-sun-sunos4':

Fully supported, including native-code generator.

`sparc-sun-solaris2':

Fully supported, including native-code generator. A couple of quirks, though: (a) the profiling libraries are bizarrely huge; (b) the default `xargs' program is atrociously bad for building GHC libraries (see section 5 Installing pre-supposed utilities for details).

HP-PA box running HP/UX 9.x:

Works registerised. No native-code generator. For GCC, you're best off with one of the Utah releases of GCC 2.6.3 (`u3' or later), from `jaguar.cs.utah.edu'. We think a straight GCC 2.7.x works, too. Concurrent/Parallel Haskell probably don't work (yet).

`i386-*-linux' (PCs running Linux -- ELF format):

GHC works registerised. You must have GCC 2.7.x or later. The iX86 native-code generator is nearly there, but it isn't turned on by default. Profiling works, and Concurrent Haskell works. Parallel Haskell probably works. On old Linux a.out systems: should be the same.

`i386-*-freebsd' (PCs running FreeBSD 2.2 or higher, and NetBSD/OpenBSD using FreeBSD emulation):

GHC works registerised. Supports same set of bundles as the above.

`i386-unknown-cygwin32':

Fully supported under Win95/NT, including a native code generator. Requires the `cygwin32' compatibility library and a healthy collection of GNU tools (i.e., gcc, GNU ld, bash etc.) Profiling works, so does Concurrent Haskell.

`mips-sgi-irix5':

GHC works registerised (no native-code generator). I suspect any GCC 2.6.x (or later) is OK. The GCC that I used was built with `--with-gnu-as'; turns out that is important! Concurrent/Parallel Haskell probably don't work (yet). Profiling might work, but it is untested.

`mips-sgi-irix6':

Thanks to the fine efforts of Tomasz Cholewo `<tjchol01@mecca.spd.louisville.edu>', GHC works registerised (no native code generator) under IRIX 6.2 and 6.3. Depends on having specially tweaked version of gcc-2.7.2 around, which can be downloaded from

  http://mecca.spd.louisville.edu/~tjchol01/software/

Profiling works, Concurrent/Parallel Haskell might work (AFAIK, untested).

`powerpc-ibm-aix':

GHC works registerised (no native-code generator..yet). I suspect 2.7.x is what you need together with this. Concurrent/Parallel Haskell probably don't work (yet). Profiling might work, but it is untested.

`m68k-apple-macos7' (Mac, using MPW):

Once upon a time, David Wright in Tasmania has actually gotten GHC to run on a Macintosh. Ditto James Thomson here at Glasgow. You may be able to get Thomson's from here. (Not sure that it will excite you to death, but...) No particularly recent GHC is known to work on a Mac.

`m68k-next-nextstep3':

Carsten Schultz succeeded with a "registerised" port of GHC 0.29. There's probably a little bit-rot since then, but otherwise it should still be fine. Concurrent/Parallel Haskell probably won't work (yet).

`m68k-sun-sunos4' (Sun3):

GHC 2.0x hasn't been tried on a Sun3. GHC 0.26 worked registerised. No native-code generator. Concurrent/Parallel Haskell probably don't work (yet).

3.2 What machines the other tools run on

Unless you hear otherwise, the other tools work if GHC works.

Haggis requires Concurrent Haskell to work.

4 Installing from binary distributions

Installing from binary distributions is easiest, and recommended! (Why binaries? Because GHC is a Haskell compiler written in Haskell, so you've got to "bootstrap" it, somehow. We provide machine-generated C-files-from-Haskell for this purpose, but it's really quite a pain to use them. If you must build GHC from its sources, using a binary-distributed GHC to do so is a sensible way to proceed. For the other `fptools' programs, many are written in Haskell, so binary distributions allow you to install them without having a Haskell compiler.)

• installing_4.1: Bundle structure.
• sect_install: Installing.
• installing_4.3: What bundles there are.
• GHC_test: Test that GHC seems to be working.

4.1 Bundle structure

Binary distributions come in "bundles," one bundle per file called `<bundle>-<platform>.tar.gz'. (See Section 3 What machines the Glasgow tools run on for what a platform is.) Suppose that you untar a binary-distribution bundle, thus:

  % cd /your/scratch/space
  % gunzip < ghc-x.xx-sun-sparc-solaris2.tar.gz | tar xvf -

Then you should find a single directory, `fptools', with the following structure:

`Makefile.in'

the raw material from which the `Makefile' will be made (section 4.2 Installing).

`configure'

the configuration script (section 4.2 Installing).

`README'

Contains this file summary.

`INSTALL'

Contains this description of how to install the bundle.

`ANNOUNCE'

The announcement message for the bundle.

`NEWS'

release notes for the bundle -- a longer version of `ANNOUNCE'. For GHC, the release notes are contained in the User Guide and this file isn't present.

`bin/<platform>'

contains platform-specific executable files to be invoked directly by the user. These are the files that must end up in your path.

`lib/<platform>'

contains platform-specific support files for the installation. Typically there is a subdirectory for each `fptools' project, whose name is the name of the project with its version number. For example, for GHC there would be a sub-directory `ghc-x.xx/' where `x.xx' is the version number of GHC in the bundle. These sub-directories have the following general structure:

`libHS.a' etc:

supporting library archives.

`ghc-iface.prl' etc:

support scripts.

`import/'

Interface files (`.hi') for the prelude.

`include/'

A few C `#include' files.

`share/'

contains platform-independent support files for the installation. Again, there is a sub-directory for each `fptools' project.

`info/'

contains Emacs info documentation files (one sub-directory per project).

`html/'

contains HTML documentation files (one sub-directory per project).

`man/'

contains Unix manual pages.

This structure is designed so that you can unpack multiple bundles (including ones from different releases or platforms) into a single `fptools' directory:

  % cd /your/scratch/space
  % gunzip < ghc-x.xx-sun-sparc-solaris2.tar.gz | tar xvf -
  % gunzip < happy-x.xx-sun-sparc-sunos4.tar.gz | tar xvf -

When you do multiple unpacks like this, the top level `Makefile', `README', and `INSTALL' get overwritten each time. That's fine -- they should be the same. Likewise, the `ANNOUNCE-<bundle>' and `NEWS-<bundle>' files will be duplicated across multiple platforms, so they will be harmlessly overwritten when you do multiple unpacks. Finally, the `share/' stuff will get harmlessly overwritten when you do multiple unpacks for one bundle on different platforms.

4.2 Installing

OK, so let's assume that you have unpacked your chosen bundles into a scratch directory `fptools'. What next? Well, you will at least need to run the `configure' script by changing your directory to `fptools' and typing `./configure'. That should convert `Makefile.in' to `Makefile'.

You can now either start using the tools in-situ without going through any installation process, just type `make in-place' to set the tools up for this (where `make' is GNU make - you might have to type `gmake' to get it). You'll also want to add the path which `make' will now echo to your `PATH' environment variable. This option is useful if you simply want to try out the package and/or you don't have the necessary priviledges (or inclination) to properly install the tools locally. Note that if you do decide to install the package `properly' at a later date, you have to go through the installation steps that follows.

To install an `fptools' package, you'll have to do the following:

1. Edit the `Makefile' and check the settings of the following variables:

   `platform'

   the platform you are going to install for.

   `bindir'

   the directory in which to install user-invokable binaries.

   `libdir'

   the directory in which to install platform-dependent support files.

   `datadir'

   the directory in which to install platform-independent support files.

   `infodir'

   the directory in which to install Emacs info files.

   `htmldir'

   the directory in which to install HTML documentation.

   `dvidir'

   the directory in which to install DVI documentation.

   The values for these variables can be set through invocation of the `configure' script that comes with the distribution, but doing an optical diff to see if the values match your expectations is always a Good Idea. Instead of running `configure', it is perfectly OK to copy `Makefile.in' to `Makefile' and set all these variables directly yourself. But do it right!

2. Run `make install'. This should work with ordinary Unix `make' -- no need for fancy stuff like GNU `make'.

3. `rehash' (t?csh users), so your shell will see the new stuff in your bin directory.

4. Once done, test your "installation" as suggested in section 4.4 Test that GHC seems to be working. Be sure to use a `-v' option, so you can see exactly what pathnames it's using. If things don't work as expected, check the list of know pitfalls section 9 Known pitfalls in building Glasgow Haskell.

When installing the user-invokable binaries, this installation procedure will install GHC as `ghc-x.xx' where `x.xx' is the version number of GHC. It will also make a link (in the binary installation directory) from `ghc' to `ghc-x.xx'. If you install multiple versions of GHC then the last one "wins", and "`ghc'" will invoke the last one installed. You can change this manually if you want. But regardless, `ghc-x.xx' should always invoke GHC version `x.xx'.

4.3 What bundles there are

There are plenty of "non-basic" GHC bundles. The files for them are called `ghc-x.xx-<bundle>-<platform>.tar.gz', where the `<platform>' is as above, and `<bundle>' is one of these:

`prof':

Profiling with cost-centres. You probably want this.

`conc':

Concurrent Haskell features. You may want this.

`par':

Parallel Haskell features (sits on top of PVM). You'll want this if you're into that kind of thing.

`gran':

The "GranSim" parallel-Haskell simulator (hmm... mainly for implementors).

`ticky':

"Ticky-ticky" profiling; very detailed information about "what happened when I ran this program" -- really for implementors.

`prof-conc':

Cost-centre profiling for Concurrent Haskell.

`prof-ticky':

Ticky-ticky profiling for Concurrent Haskell.

One likely scenario is that you will grab three binary bundles -- basic, profiling, and concurrent.

4.4 Test that GHC seems to be working

The way to do this is, of course, to compile and run this program (in a file `Main.hs'):

main = putStr "Hello, world!\n"

First, give yourself a convenient way to execute the driver script `ghc/driver/ghc', perhaps something like...

% ln -s /local/src/ghc-x.xx/ghc/driver/ghc ~/bin/alpha/ghc
% rehash

Compile the program, using the `-v' (verbose) flag to verify that libraries, etc., are being found properly:

% ghc -v -o hello Main.hs

Now run it:

% ./hello
Hello, world!

Some simple-but-profitable tests are to compile and run the notorious `nfib' program, using different numeric types. Start with `nfib :: Int -> Int', and then try `Integer', `Float', `Double', `Rational' and maybe `Complex Float'. Code for this is distributed in `ghc/misc/examples/nfib/'.

For more information on how to "drive" GHC, either do `ghc -help' or consult the User's Guide (distributed in `ghc/docs/users_guide').

5 Installing pre-supposed utilities

Here are the gory details about some utility programs you may need; `perl' and `gcc' are the only important ones. (PVM is important if you're going for Parallel Haskell.) The `configure' script will tell you if you are missing something.

Perl:

You have to have Perl to proceed! Perl is a language quite good for doing shell-scripty tasks that involve lots of text processing. It is pretty easy to install. Perl 5 is the current version; GHC should be Perl 4 friendly though. For Win32 platforms, Perl 5 is recommended, we even strongly suggest you pick up a port of Perl 5 for `cygwin32', as the common Hip/ActiveWare port of Perl is not Cool Enough for our purposes. Perl should be put somewhere so that it can be invoked by the `#!' script-invoking mechanism. (I believe `/usr/bin/perl' is preferred; we use `/usr/local/bin/perl' at Glasgow.) The full pathname should be less than 32 characters long.

GNU C (`gcc'):

The current version is 2.7.2. If your GCC dies with "internal error" on some GHC source file, please let us know, so we can report it and get things improved. (Exception: on `iX86' boxes -- you may need to fiddle with GHC's `-monly-N-regs' option; ask if confused...)

PVM version 3:

PVM is the Parallel Virtual Machine on which Parallel Haskell programs run. (You only need this if you plan to run Parallel Haskell. Concurent Haskell, which runs concurrent threads on a uniprocessor doesn't need it.) Underneath PVM, you can have (for example) a network of workstations (slow) or a multiprocessor box (faster). The current version of PVM is 3.3.11; we use 3.3.7. It is readily available on the net; I think I got it from `research.att.com', in `netlib'. A PVM installation is slightly quirky, but easy to do. Just follow the `Readme' instructions.

`xargs' on Solaris2:

The GHC libraries are put together with something like:

find bunch-of-dirs -name '*.o' -print | xargs ar q ...

Unfortunately the Solaris `xargs' (the shell-script equivalent of `map') only "bites off" the `.o' files a few at a time -- with near-infinite rebuilding of the symbol table in the `.a' file. The best solution is to install a sane `xargs' from the GNU findutils distribution. You can unpack, build, and install the GNU version in the time the Solaris `xargs' mangles just one GHC library.

`bash' (Parallel Haskell only):

Sadly, the `gr2ps' script, used to convert "parallelism profiles" to PostScript, is written in Bash (GNU's Bourne Again shell). This bug will be fixed (someday).

Makeindex:

You won't need this unless you are re-making our documents. Makeindex normally comes with a TeX distribution, but if not, we can provide the latest and greatest.

Tgrind:

This is required only if you remake lots of our documents and you use the `-t tgrind' option with `lit2latex' (also literate programming), to do "fancy" typesetting of your code. Unlikely.

Flex:

This is a quite-a-bit-better-than-Lex lexer. Used in the literate-programming stuff. You won't need it unless you're hacking on some of our more obscure stuff. On our machines, the version in `/bin' doesn't work; you need the GNU version. Find out by saying `flex --version' (our current version is 2.5.3, but maybe earlier ones will work). If it doesn't know about the `--version' flag, it ain't the right `flex'.

Yacc:

If you mess with the Haskell parser, you'll need a Yacc that can cope. The unbundled `/usr/lang/yacc' is OK; the GNU `bison' is OK; Berkeley yacc, `byacc', is not OK.

`sed'

You need a working `sed' if you are going to build from sources. The build-configuration stuff needs it. GNU sed version 2.0.4 is no good! It has a bug in it that is tickled by the build-configuration. 2.0.5 is ok. Others are probably ok too (assuming we don't create too elaborate configure scripts..)

Two `fptools' projects are worth a quick note at this point, because they are useful for all the others:

• `glafp-utils' contains several utilities which aren't particularly Glasgow-ish, but Occasionally Indispensable. Like `lndir' for creating symbolic link trees.

• `literate' contains the Glasgow-built tools for generating documentation. (The unoriginal idea is to be able to generate `latex', `info', and program code from a single source file.) To get anywhere you'll need at least `lit2pgm', either from the `literate' project, or because it's already installed on your system.

6 Building from source

You've been rash enough to want to build some of the Glasgow Functional Programming tools (GHC, Happy, nofib, etc) from source. You've slurped the source, from the CVS repository or from a source distribution, and now you're sitting looking at a huge mound of bits, wondering what to do next.

Gingerly, you type `make all'. Wrong already!

This rest of this guide is intended for duffers like me, who aren't really interested in Makefiles and systems configurations, but who need a mental model of the interlocking pieces so that they can make them work, extend them consistently when adding new software, and lay hands on them gently when they don't work.

• installing_6.1: Your source tree.
• installing_6.2: Build trees.
• installing_6.3: Getting the build you want.
• installing_6.4: The story so far.
• installing_6.5: Making things.
• sect_standard-targets: Standard targets.
• installing_6.7: Other targets.

6.1 Your source tree

The source code is held in your source tree. The root directory of your source tree must contain the following directories and files:

• `Makefile': the root Makefile.

• `mk/': the directory that contains the main Makefile code, shared by all the `fptools' software.

• `configure.in', `config.sub', `config.guess': these files support the configuration process.

• `install-sh'.

All the other directories are individual projects of the `fptools' system -- for example, the Glasgow Haskell Compiler (`ghc'), the Happy parser generator (`happy'), the `nofib' benchmark suite, and so on. You can have zero or more of these. Needless to say, some of them are needed to build others. For example, you need `happy' to build `ghc'. You can either grab `happy' too, or else you can use a version of `happy' that's already installed on your system, or grab a binary distribution of `happy' and install it.

The important thing to remember is that even if you want only one project (`happy', say), you must have a source tree whose root directory contains `Makefile', `mk/', `configure.in', and the project(s) you want (`happy/' in this case). You cannot get by with just the `happy/' directory.

6.2 Build trees

While you can build a system in the source tree, we don't recommend it. We often want to build multiple versions of our software for different architectures, or with different options (e.g. profiling). It's very desirable to share a single copy of the source code among all these builds.

So for every source tree we have zero or more build trees. Each build tree is initially an exact copy of the source tree, except that each file is a symbolic link to the source file, rather than being a copy of the source file. There are "standard" Unix utilities that make such copies, so standard that they go by different names: `lndir', `mkshadowdir' are two (If you don't have either, the source distribution includes sources for the `X11' `lndir' -- check out `fptools/glafp-utils/lndir' ).

The build tree does not need to be anywhere near the source tree in the file system. Indeed, one advantage of separating the build tree from the source is that the build tree can be placed in a non-backed-up partition, saving your systems support people from backing up untold megabytes of easily-regenerated, and rapidly-changing, gubbins. The golden rule is that (with a single exception -- Section 6.3 Getting the build you want) absolutely everything in the build tree is either a symbolic link to the source tree, or else is mechanically generated. It should be perfectly OK for your build tree to vanish overnight; an hour or two compiling and you're on the road again.

You need to be a bit careful, though, that any new files you create (if you do any development work) are in the source tree, not a build tree!

Remember, that the source files in the build tree are symbolic links to the files in the source tree. (The build tree soon accumulates lots of built files like `Foo.o', as well.) You can delete a source file from the build tree without affecting the source tree (though it's an odd thing to do). On the other hand, if you edit a source file from the build tree, you'll edit the source-tree file directly. (You can set up Emacs so that if you edit a source file from the build tree, Emacs will silently create an edited copy of the source file in the build tree, leaving the source file unchanged; but the danger is that you think you've edited the source file whereas actually all you've done is edit the build-tree copy. More commonly you do want to edit the source file.)

Like the source tree, the top level of your build tree must (a linked copy of) the root directory of the `fptools' suite. Inside Makefiles, the root of your build tree is called `$(FPTOOLS_TOP)'. In the rest of this document path names are relative to `$(FPTOOLS_TOP)' unless otherwise stated. For example, the file `ghc/mk/target.mk' is actually `$(FPTOOLS_TOP)/ghc/mk/target.mk'.

6.3 Getting the build you want

When you build `fptools' you will be compiling code on a particular host platform, to run on a particular target platform (usually the same as the host platform). The difficulty is that there are minor differences between different platforms; minor, but enough that the code needs to be a bit different for each. There are some big differences too: for a different architecture we need to build GHC with a different native-code generator.

There are also knobs you can turn to control how the `fptools' software is built. For example, you might want to build GHC optimised (so that it runs fast) or unoptimised (so that you can compile it fast after you've modified it. Or, you might want to compile it with debugging on (so that extra consistency-checking code gets included) or off. And so on.

All of this stuff is called the configuration of your build. You set the configuration using an exciting three-step process.

Step 1: get ready for configuration.

Change directory to `$(FPTOOLS)' and issue the command `autoconf' (with no arguments). This GNU program converts `$(FPTOOLS)/configure.in' to a shell script called `$(FPTOOLS)/configure'. Both these steps are completely platform-independent; they just mean that the human-written file (`configure.in') can be short, although the resulting shell script, `configure', and `mk/config.h.in', are long. In case you don't have `autoconf' we distribute the results, `configure', and `mk/config.h.in', with the source distribution. They aren't kept in the repository, though.

Step 2: system configuration.

Runs the newly-created `configure' script, thus:

  ./configure

`configure''s mission is to scurry round your computer working out what architecture it has, what operating system, whether it has the `vfork' system call, where `yacc' is kept, whether `gcc' is available, where various obscure `#include' files are, whether it's a leap year, and what the systems manager had for lunch. It communicates these snippets of information in two ways:

• It translates `mk/config.mk.in' to `mk/config.mk', substituting for things between "`@'" brackets. So, "`HaveGcc`''" will be replaced by "`YES'" or "`NO'" depending on what `configure' finds. `mk/config.mk' is included by every Makefile (directly or indirectly), so the configuration information is thereby communicated to all Makefiles.

• It translates `mk/config.h.in' to `mk/config.h'. The latter is `#include'd by various C programs, which can thereby make use of configuration information.

`configure' caches the results of its run in `config.cache'. Quite often you don't want that; you're running `configure' a second time because something has changed. In that case, simply delete `config.cache'.

Step 3: build configuration.

Next, you say how this build of `fptools' is to differ from the standard defaults by creating a new file `mk/build.mk' in the build tree. This file is the one and only file you edit in the build tree, precisely because it says how this build differs from the source. (Just in case your build tree does die, you might want to keep a private directory of `build.mk' files, and use a symbolic link in each build tree to point to the appropriate one.) So `mk/build.mk' never exists in the source tree -- you create one in each build tree from the template. We'll discuss what to put in it shortly.

And that's it for configuration. Simple, eh?

What do you put in your build-specific configuration file `mk/build.mk'? For almost all purposes all you will do is put make variable definitions that override those in `mk/config.mk.in'. The whole point of `mk/config.mk.in' -- and its derived counterpart `mk/config.mk' -- is to define the build configuration. It is heavily commented, as you will see if you look at it. So generally, what you do is edit `mk/config.mk.in' (read-only), and add definitions in `mk/build.mk' that override any of the `config.mk' definitions that you want to change. (The override occurs because the main boilerplate file, `mk/boilerplate.mk', includes `build.mk' after `config.mk'.)

For example, `config.mk.in' contains the definition:

  ProjectsToBuild = glafp-utils literate happy ghc hslibs

The accompanying comment explains that this is the list of enabled projects; that is, if (after configuring) you type `gmake all' in `FPTOOLS_TOP' three specified projects will be made. If you want to add `green-card', you can add this line to `build.mk':

  ProjectsToBuild += green-card

or, if you prefer,

  ProjectsToBuild = glafp-utils literate happy ghc hslibs green-card

(GNU `make' allows existing definitions to have new text appended using the "`+='" operator, which is quite a convenient feature.)

When reading `config.mk.in', remember that anything between "`...`''" signs is going to be substituted by `configure' later. You can override the resulting definition if you want, but you need to be a bit surer what you are doing. For example, there's a line that says:

  YACC = @Yacc@

This defines the Make variables `YACC' to the pathname for a Yacc that `configure' finds somewhere. If you have your own pet Yacc you want to use instead, that's fine. Just add this line to `mk/build.mk':

  YACC = myyacc

You do not have to have a `mk/build.mk' file at all; if you don't, you'll get all the default settings from `mk/config.mk.in'.

You can also use `build.mk' to override anything that `configure' got wrong. One place where this happens often is with the definition of `FPTOOLS_TOP_ABS': this variable is supposed to be the canonical path to the top of your source tree, but if your system uses an automounter then the correct directory is hard to find automatically. If you find that `configure' has got it wrong, just put the correct definition in `build.mk'.

6.4 The story so far

Let's summarise the steps you need to carry to get yourself a fully-configured build tree from scratch.

1. Get your source tree from somewhere (CVS repository or source distribution). Say you call the root directory `myfptools' (it does not have to be called `fptools'). Make sure that you have the essential files (see Section 6.1 Your source tree).

2. Use `lndir' or `mkshadowdir' to create a build tree.

       cd myfptools
       mkshadowdir . /scratch/joe-bloggs/myfptools-sun4
   

   You probably want to give the build tree a name that suggests its main defining characteristic (in your mind at least), in case you later add others.

3. Change directory to the build tree. Everything is going to happen there now.

       cd /scratch/joe-bloggs/myfptools-sun4
   

4. Prepare for system configuration:

       autoconf
   

   (You can skip this step if you are starting from a source distribution, and you already have `configure' and `mk/config.h.in'.)

5. Do system configuration:

       ./configure
   

6. Create the file `mk/build.mk', adding definitions for your desired configuration options.

       emacs mk/build.mk
   

You can make subsequent changes to `mk/build.mk' as often as you like. You do not have to run any further configuration programs to make these changes take effect. In theory you should, however, say `gmake clean', `gmake all', because configuration option changes could affect anything -- but in practice you are likely to know what's affected.

6.5 Making things

At this point you have made yourself a fully-configured build tree, so you are ready to start building real things.

The first thing you need to know is that you must use GNU `make', usually called `gmake', not standard Unix `make'. If you use standard Unix `make' you will get all sorts of error messages (but no damage) because the `fptools' `Makefiles' use GNU `make''s facilities extensively.

6.6 Standard targets

In any directory you should be able to make the following:

`boot':

does the one-off preparation required to get ready for the real work. Notably, it does `gmake depend' in all directories that contain programs. But `boot' does more. For example, you can't do `gmake depend' in a directory of C program until you have converted the literate `.lh' header files into standard `.h' header files. Similarly, you convert a literate file to illiterate form until you have built the `literate' tools. `boot' takes care of these inter-directory dependencies. You should say `gmake boot' right after configuring your build tree, but note that this is a one-off, i.e., there's no need to re-do `gmake boot' if you should re-configure your build tree at a later stage (no harm caused if you do though).

`all':

makes all the final target(s) for this Makefile. Depending on which directory you are in a "final target" may be an executable program, a library archive, a shell script, or a Postscript file. Typing `gmake' alone is generally the same as typing `gmake all'.

`install':

installs the things built by `all'. Where does it install them? That is specified by `mk/config.mk.in'; you can override it in `mk/build.mk'.

`uninstall':

reverses the effect of `install'.

`clean':

remove all easily-rebuilt files.

`veryclean':

remove all files that can be rebuilt at all. There's a danger here that you may remove a file that needs a more obscure utility to rebuild it (especially if you started from a source distribution).

`check':

run the test suite.

All of these standard targets automatically recurse into sub-directories. Certain other standard targets do not:

`configure':

is only available in the root directory `$(FPTOOLS)'; it has been discussed in Section 6.3 Getting the build you want.

`depend':

make a `.depend' file in each directory that needs it. This `.depend' file contains mechanically-generated dependency information; for example, suppose a directory contains a Haskell source module `Foo.lhs' which imports another module `Baz'. Then the generated `.depend' file will contain the dependency:

  Foo.o : Baz.hi

which says that the object file `Foo.o' depends on the interface file `Baz.hi' generated by compiling module `Baz'. The `.depend' file is automatically included by every Makefile.

`binary-dist':

make a binary distribution.

`dist':

make a source distribution.

6.7 Other targets

Most `Makefiles' have targets other than these. You can find this out by looking in the `Makefile' itself.

7 The `Makefile' architecture

`make' is great if everything works -- you type `gmake install' and, lo, the right things get compiled and installed in the right places. Our goal is to make this happen often, but somehow it often doesn't; instead some wierd error message eventually emerges from the bowels of a directory you didn't know existed.

The purpose of this section is to give you a road-map to help you figure out what is going right and what is going wrong.

• installing_7.1: A small project.
• installing_7.2: A larger project.
• installing_7.3: Boilerplate architecture.
• installing_7.4: The main `mk/boilerplate.mk' file.
• sect_suffix: Pattern rules and options.
• installing_7.6: The main `mk/target.mk' file.
• installing_7.7: Recursion.
• installing_7.8: Way management.
• installing_7.9: When the canned rule isn't right.

7.1 A small project

To get started, let us look at the `Makefile' for an imaginary small `fptools' project, `small'. Each project in `fptools' has its own directory in `FPTOOLS_TOP', so the `small' project will have its own directory `FPOOLS_TOP/small/'. Inside the `small/' directory there will be a `Makefile', looking something like this:

  #     Makefile for fptools project "small"

  TOP = ..
  include $(TOP)/mk/boilerplate.mk

  SRCS = $(wildcard *.lhs) $(wildcard *.c)
  HS_PROG = small

  include $(TOP)/target.mk

This `Makefile' has three sections:

1. The first section includes(1) a file of "boilerplate" code from the level above (which in this case will be `FPTOOLS_TOP/mk/boilerplate.mk'). As its name suggests, `boilerplate.mk' consists of a large quantity of standard `Makefile' code. We discuss this boilerplate in more detail in Section 7.4 The main `mk/boilerplate.mk' file. Before the `include' statement, you must define the `make' variable `TOP' to be the directory containing the `mk' directory in which the `boilerplate.mk' file is. It is not OK to simply say

     include ../mk/boilerplate.mk  # NO NO NO
   

   Why? Because the `boilerplate.mk' file needs to know where it is, so that it can, in turn, `include' other files. (Unfortunately, when an `include'd file does an `include', the filename is treated relative to the directory in which `gmake' is being run, not the directory in which the `included' sits.) In general, every file `foo.mk' assumes that `$(TOP)/mk/foo.mk' refers to itself. It is up to the `Makefile' doing the `include' to ensure this is the case. Files intended for inclusion in other `Makefile's are written to have the following property: after `foo.mk' is `include'd, it leaves `TOP' containing the same value as it had just before the `include' statement. In our example, this invariant guarantees that the `include' for `target.mk' will look in the same directory as that for `boilerplate.mk'.

2. The second section defines the following standard `make' variables: `SRCS' (the source files from which is to be built), and `HS_PROG' (the executable binary to be built). We will discuss in more detail what the "standard variables" are, and how they affect what happens, in Section 7.6 The main `mk/target.mk' file. The definition for `SRCS' uses the useful GNU `make' construct `$(wildcard' pat`)', which expands to a list of all the files matching the pattern pat in the current directory. In this example, `SRCS' is set to the list of all the `.lhs' and `.c' files in the directory. (Let's suppose there is one of each, `Foo.lhs' and `Baz.c'.)

3. The last section includes a second file of standard code, called `target.mk'. It contains the rules that tell `gmake' how to make the standard targets (Section 6.6 Standard targets). Why, you ask, can't this standard code be part of `boilerplate.mk'? Good question. We discuss the reason later, in Section 7.3 Boilerplate architecture. You do not have to `include' the `target.mk' file. Instead, you can write rules of your own for all the standard targets. Usually, though, you will find quite a big payoff from using the canned rules in `target.mk'; the price tag is that you have to understand what canned rules get enabled, and what they do (Section 7.6 The main `mk/target.mk' file).

In our example `Makefile', most of the work is done by the two `include'd files. When you say `gmake all', the following things happen:

• `gmake' figures out that the object files are `Foo.o' and `Baz.o'.

• It uses a boilerplate pattern rule to compile `Foo.lhs' to `Foo.o' using a Haskell compiler. (Which one? That is set in the build configuration.)

• It uses another standard pattern rule to compile `Baz.c' to `Baz.o', using a C compiler. (Ditto.)

• It links the resulting `.o' files together to make `small', using the Haskell compiler to do the link step. (Why not use `ld'? Because the Haskell compiler knows what standard librarise to link in. How did `gmake' know to use the Haskell compiler to do the link, rather than the C compiler? Because we set the variable `HS_PROG' rather than `C_PROG'.)

All `Makefile's should follow the above three-section format.

7.2 A larger project

Larger projects are usually structured into a nummber of sub-directories, each of which has its own `Makefile'. (In very large projects, this sub-structure might be iterated recursively, though that is rare.) To give you the idea, here's part of the directory structure for the (rather large) `ghc' project:

  $(FPTOOLS_TOP)/ghc/
    Makefile

    mk/
      boilerplate.mk
      rules.mk

    docs/
      Makefile
      ...source files for documentation...

    driver/
      Makefile
      ...source files for driver...

    compiler/
      Makefile
      parser/...source files for parser...
      renamer/...source files for renamer...
      ...etc...

The sub-directories `docs', `driver', `compiler', and so on, each contains a sub-component of `ghc', and each has its own `Makefile'. There must also be a `Makefile' in `$(FPTOOLS_TOP)/ghc'. It does most of its work by recursively invoking `gmake' on the `Makefile's in the sub-directories. We say that `ghc/Makefile' is a non-leaf `Makefile', because it does little except organise its children, while the `Makefile's in the sub-directories are all leaf `Makefile's. (In principle the sub-directories might themselves contain a non-leaf `Makefile' and several sub-sub-directories, but that does not happen in `ghc'.)

The `Makefile' in `ghc/compiler' is considered a leaf `Makefile' even though the `ghc/compiler' has sub-directories, because these sub-directories do not themselves have `Makefile' in them. They are just used to structure the collection of modules that make up `ghc', but all are managed by the single `Makefile' in `ghc/compiler'.

You will notice that `ghc/' also contains a directory `ghc/mk/'. It contains `ghc'-specific `Makefile' boilerplate code. More precisely:

• `ghc/mk/boilerplate.mk' is included at the top of `ghc/Makefile', and of all the leaf `Makefile's in the sub-directories. It in turn `include's the main boilerplate file `mk/boilerplate.mk'.

• `ghc/mk/target.mk' is `include'd at the bottom of `ghc/Makefile', and of all the leaf `Makefiles' in the sub-directories. It in turn `include's the file `mk/target.mk'.

So these two files are the place to look for `ghc'-wide customisation of the standard boilerplate.

7.3 Boilerplate architecture

Every `Makefile' includes a `boilerplate.mk' file at the top, and `target.mk' file at the bottom. In this section we discuss what is in these files, and why there have to be two of them. In general:

• `boilerplate.mk' consists of:

  • Definitions of millions of `make' variables that collectively specify the build configuration. Examples: `HC_OPTS', the options to feed to the Haskell compiler; `NoFibSubDirs', the sub-directories to enable within the `nofib' project; `GhcWithHc', the name of the Haskell compiler to use when compiling `GHC' in the `ghc' project.

  • Standard pattern rules that tell `gmake' how to construct one file from another.
  `boilerplate.mk' needs to be `include'd at the top of each `Makefile', so that the user can replace the boilerplate definitions or pattern rules by simply giving a new definition or pattern rule in the `Makefile'. `gmake' simply takes the last definition as the definitive one. Instead of replacing boilerplate definitions, it is also quite common to augment them. For example, a `Makefile' might say:

    SRC_HC_OPTS += -O
  

  thereby adding "`-O'" to the end of `SRC_HC_OPTS'.

• `target.mk' contains `make' rules for the standard targets described in Section 6.6 Standard targets. These rules are selectively included, depending on the setting of certain `make' variables. These variables are usually set in the middle section of the `Makefile' between the two `include's. `target.mk' must be included at the end (rather than being part of `boilerplate.mk') for several tiresome reasons:

  • `gmake' commits target and dependency lists earlier than it should. For example, `target.mk' has a rule that looks like this:

      $(HS_PROG) : $(OBJS)
            $(HC) $(LD_OPTS) $< -o $@
    

    If this rule was in `boilerplate.mk' then `$(HS_PROG)' and `$(OBJS)' would not have their final values at the moment `gmake' encountered the rule. Alas, `gmake' takes a snapshot of their current values, and wires that snapshot into the rule. (In contrast, the commands executed when the rule "fires" are only substituted at the moment of firing.) So, the rule must follow the definitions given in the `Makefile' itself.

  • Unlike pattern rules, ordinary rules cannot be overriden or replaced by subsequent rules for the same target (at least not without an error message). Including ordinary rules in `boilerplate.mk' would prevent the user from writing rules for specific targets in specific cases.

  • There are a couple of other reasons I've forgotten, but it doesn't matter too much.

7.4 The main `mk/boilerplate.mk' file

If you look at `$(FPTOOLS_TOP)/mk/boilerplate.mk' you will find that it consists of the following sections, each held in a separate file:

`config.mk'

is the build configuration file we discussed at length in Section 6.3 Getting the build you want.

`paths.mk'

defines `make' variables for pathnames and file lists. In particular, it gives definitions for:

`SRCS':

all source files in the current directory.

`HS_SRCS':

all Haskell source files in the current directory. It is derived from `$(SRCS)', so if you override `SRCS' with a new value `HS_SRCS' will follow suit.

`C_SRCS':

similarly for C source files.

`HS_OBJS':

the `.o' files derived from `$(HS_SRCS)'.

`C_OBJS':

similarly for `$(C_SRCS)'.

`OBJS':

the concatenation of `$(HS_OBJS)' and `$(C_OBJS)'.

Any or all of these definitions can easily be overriden by giving new definitions in your `Makefile'. For example, if there are things in the current directory that look like source files but aren't, then you'll need to set `SRCS' manually in your `Makefile'. The other definitions will then work from this new definition. What, exactly, does `paths.mk' consider a "source file" to be. It's based the file's suffix (e.g. `.hs', `.lhs', `.c', `.lc', etc), but this is the kind of detail that changes more rapidly, so rather than enumerate the source suffices here the best thing to do is to look in `paths.mk'.

`opts.mk'

defines `make' variables for option strings to pass to each program. For example, it defines `HC_OPTS', the option strings to pass to the Haskell compiler. See section 7.5 Pattern rules and options.

`suffix.mk'

defines standard pattern rules -- see section 7.5 Pattern rules and options

Any of the variables and pattern rules defined by the boilerplate file can easily be overridden in any particular `Makefile', because the boilerplace `include' comes first. Definitions after this `include' directive simply override the default ones in `boilerplate.mk'.

7.5 Pattern rules and options

The file `suffix.mk' defines standard pattern rules that say how to build one kind of file from another, for example, how to build a `.o' file from a `.c' file. (GNU `make''s pattern rules are more powerful and easier to use than Unix `make''s suffix rules.)

Almost all the rules look something like this:

%.o : %.c
        @$(RM) $@
        $(CC) $(CC_OPTS) -c $< -o $@

Here's how to understand the rule. It says that something.o (say `Foo.o') can be built from something.c (`Foo.c'), by invoking the C compiler (path name held in `$(CC)'), passing to it the options `$(CC_OPTS)' and the rule's dependent file of the rule `$<' (`Foo.c' in this case), and putting the result in the rule's target `$@' (`Foo.o' in this case).

Every program is held in a `make' variable defined in `mk/config.mk' -- look in `mk/config.mk' for the complete list. One important one is the Haskell compiler, which is called `$(HC)'.

Every programs options are are held in a `make' variables called `<prog>_OPTS'. the `<prog>_OPTS' variables are defined in `mk/opts.mk'. Almost all of them are defined like this:

  CC_OPTS = $(SRC_CC_OPTS) $(WAY$(_way)_CC_OPTS) $($*_CC_OPTS) $(EXTRA_CC_OPTS)

The four variables from which `CC_OPTS' is built have the following meaning:

`SRC_CC_OPTS':

options passed to all C compilations.

`WAY_<way>_CC_OPTS':

options passed to C compilations for way `<way>'. For example, `WAY_mp_CC_OPTS' gives options to pass to the C compiler when compiling way `mp'. The variable `WAY_CC_OPTS' holds options to pass to the C compiler when compiling the standard way. (Section 7.8 Way management dicusses multi-way compilation.)

`<module>_CC_OPTS':

options to pass to the C compiler that are specific to module `<module>'. For example, `SMap_CC_OPTS' gives the specific options to pass to the C compiler when compiling `SMap.c'.

`EXTRA_CC_OPTS':

extra options to pass to all C compilations. This is intended for command line use, thus;

  gmake libHS.a EXTRA_CC_OPTS="-v"

7.6 The main `mk/target.mk' file

`target.mk' contains canned rules for all the standard targets described in Section 6.6 Standard targets. It is complicated by the fact that you don't want all of these rules to be active in every `Makefile'. Rather than have a plethora of tiny files which you can include selectively, there is a single file, `target.mk', which selectively includes rules based on whether you have defined certain variables in your `Makefile'. This section explains what rules you get, what variables control them, and what the rules do. Hopefully, you will also get enough of an idea of what is supposed to happen that you can read and understand any wierd special cases yourself.

`HS_PROG'.

If `HS_PROG' is defined, you get rules with the following targets:

`HS_PROG'

itself. This rule links `$(OBJS)' with the Haskell runtime system to get an executable called `$(HS_PROG)'.

`install'

installs `$(HS_PROG)' in `$(bindir)' with the execute bit set.

`C_PROG'

is similar to `HS_PROG', except that the link step links `$(C_OBJS)' with the C runtime system.

`LIBRARY'

is similar to `HS_PROG', except that it links `$(LIB_OBJS)' to make the library archive `$(LIBRARY)', and `install' installs it in `$(libdir)', with the execute bit not set.

`LIB_DATA'

...

`LIB_EXEC'

...

`HS_SRCS', `C_SRCS'.

If `HS_SRCS' is defined and non-empty, a rule for the target `depend' is included, which generates dependency information for Haskell programs. Similarly for `C_SRCS'.

All of these rules are "double-colon" rules, thus

  install :: $(HS_PROG)
        ...how to install it...

GNU `make' treats double-colon rules as separate entities. If there are several double-colon rules for the same target it takes each in turn and fires it if its dependencies say to do so. This means that you can, for example, define both `HS_PROG' and `LIBRARY', which will generate two rules for `install'. When you type `gmake install' both rules will be fired, and both the program and the library will be installed, just as you wanted.

7.7 Recursion

In leaf `Makefiles' the variable `SUBDIRS' is undefined. In non-leaf `Makefiles', `SUBDIRS' is set to the list of sub-directories that contain subordinate `Makefile's. It is up to you to set `SUBDIRS' in the `Makefile'. There is no automation here -- `SUBDIRS' is too important automate.

When `SUBDIRS' is defined, `target.mk' includes a rather neat rule for the standard targets (Section 6.6 Standard targets) that simply invokes `make' recursively in each of the sub-directories.

These recursive invocations are guaranteed to occur in the order in which the list of directories is specified in `SUBDIRS'. This guarantee can be important. For example, when you say `gmake boot' it can be important that the recursive invocation of `make boot' is done in one sub-directory (the include files, say) before another (the source files). Generally, put the most independent sub-directory first, and the most dependent last.

7.8 Way management

We sometimes want to build essentially the same system in several different "ways". For example, we want to build `ghc''s `Prelude' libraries with and without profiling, with and without concurrency, and so on, so that there is an appropriately-built library archive to link with when the user compiles his program. It would be possible to have a completely separate build tree for each such "way", but it would be horribly bureaucratic, especially since often only parts of the build tree need to be constructed in multiple ways.

Instead, the `template.mk' contains some clever magic to allow you to build several versions of a system; and to control locally how many versions are built and how they differ. This section explains the magic.

The files for a particular way are distinguished by munging the suffix. The "normal way" is always built, and its files have the standard suffices `.o', `.hi', and so on. In addition, you can build one or more extra ways, each distinguished by a way tag. The object files and interface files for one of these extra ways are distinguished by their suffix. For example, way `mp' has files `.mp_o' and `.mp_hi'. Library archives have their way tag the other side of the dot, for boring reasons; thus, `libHS_mp.a'.

A `make' variable called `way' holds the current way tag. `way' is only ever set on the command line of a recursive invocation of `gmake'. It is never set inside a `Makefile'. So it is a global constant for any one invocation of `gmake'. Two other `make' variables, `way_' and `_way' are immediately derived from `$(way)' and never altered. If `way' is not set, then neither are `way_' and `_way', and the invocation of `make' will build the "normal way". If `way' is set, then the other two variables are set in sympathy. For example, if `$(way)' is "`mp'", then `way_' is set to "`mp_'" and `_way' is set to "`_mp'". These three variables are then used when constructing file names.

So how does `make' ever get recursively invoked with `way' set? There are two ways in which this happens:

• For some (but not all) of the standard targets, when in a leaf sub-directory, `make' is recursively invoked for each way tag in `$(WAYS)'. You set `WAYS' to the list of way tags you want these targets built for. The mechanism here is very much like the recursive invocation of `make' in sub-directories (Section 7.7 Recursion). It is up to you to set `WAYS' in your `Makefile'; this is how you control what ways will get built.

• For a useful collection of targets (such as `libHS_mp.a', `Foo.mp_o') there is a rule which recursively invokes `make' to make the specified target, setting the `way' variable. So if you say `gmake Foo.mp_o' you should see a recursive invocation `gmake Foo.mp_o way=mp', and in this recursive invocation the pattern rule for compiling a Haskell file into a `.o' file will match. The key pattern rules (in `suffix.mk') look like this:

    %.$(way_)o : %.lhs
          $(HC) $(HC_OPTS) $< -o $@
  

  Neat, eh?

7.9 When the canned rule isn't right

Sometimes the canned rule just doesn't do the right thing. For example, in the `nofib' suite we want the link step to print out timing information. The thing to do here is not to define `HS_PROG' or `C_PROG', and instead define a special purpose rule in your own `Makefile'. By using different variable names you will avoid the canned rules being included, and conflicting with yours.

8 Booting/porting from C (`.hc') files

This section is for people trying to get GHC going by using the supplied intermediate C (`.hc') files. This would probably be because no binaries have been provided, or because the machine is not "fully supported."

The intermediate C files are normally made available together with a source release, please check the announce message for exact directions of where to find them. If we've haven't made them available or you can't find them, please ask.

Assuming you've got them, unpack them on top of a fresh source tree. Then follow the `normal' instructions in section 6 Building from source for setting up a build tree and configuring it. The only extra thing to remember when booting from `.hc' files is to add the following line to the `build.mk' file:

GhcWithHscBuiltViaC=YES

and proceed with doing a `make boot' followed by a `make all'.

That's the mechanics of the boot process, but, of course, if you're trying to boot on a platform that is not supported and significantly `different' from any of the supported ones, this is only the start of the adventure...(ToDo: porting tips - stuff to look out for, etc.)

9 Known pitfalls in building Glasgow Haskell

WARNINGS about pitfalls and known "problems":

1. One difficulty that comes up from time to time is running out of space in `/tmp'. (It is impossible for the configuration stuff to compensate for the vagaries of different sysadmin approaches re temp space.) The quickest way around it is `setenv TMPDIR /usr/tmp' or even `setenv TMPDIR .' (or the equivalent incantation with the shell of your choice). The best way around it is to say

   export TMPDIR=<dir>
   

   in your `build.mk' file. Then GHC and the other `fptools' programs will use the appropriate directory in all cases.

2. In compiling some support-code bits, e.g., in `ghc/runtime/gmp' and even in `ghc/lib', you may get a few C-compiler warnings. We think these are OK.

3. When compiling via C, you'll sometimes get "warning: assignment from incompatible pointer type" out of GCC. Harmless.

4. Similarly, `ar'chiving warning messages like the following are not a problem:

   ar: filename GlaIOMonad__1_2s.o truncated to GlaIOMonad_
   ar: filename GlaIOMonad__2_2s.o truncated to GlaIOMonad_
   ...
   

5. Also harmless are some specialisation messages that you may see when compiling GHC; e.g.:

   SPECIALISATION MESSAGES (Desirable):
   *** INSTANCES
   {-# SPECIALIZE instance Eq [Class] #-}
   {-# SPECIALIZE instance Eq (Class, [Class]) #-}
   {-# SPECIALIZE instance Outputable [ClassOp] #-}
   {-# SPECIALIZE instance Outputable [Id] #-}
   

6. In compiling the compiler proper (in `compiler/'), you may get an "Out of heap space" error message. These can vary with the vagaries of different systems, it seems. The solution is simple: (1) add a suitable `-H' flag to the `<module>_HC_OPTS' `make' variable in the appropriate `Makefile'; (2) try again: `gmake'. (Section 7.5 Pattern rules and options.) Alternatively, just cut to the chase scene:

   % cd ghc/compiler
   % make EXTRA_HC_OPTS=-H32m  # or some nice big number
   

7. Not too long into the build process, you may get a huge complaint of the form:

   Giant error 'do'ing getopts.pl:  at ./lit2pgm.BOOT line 27.
   

   This indicates that your `perl' was mis-installed; the binary is unable to find the files for its "built-in" library. Speak to your perl installer, then re-try.

8. If you try to compile some Haskell, and you get errors from GCC about lots of things from `/usr/include/math.h', then your GCC was mis-installed. `fixincludes' wasn't run when it should've been. As `fixincludes' is now automagically run as part of GCC installation, this bug also suggests that you have an old GCC.

9. You may need to re-`ranlib' your libraries (on Sun4s).

   % cd $(libdir)/ghc-x.xx/sparc-sun-sunos4
   % foreach i ( `find . -name '*.a' -print` ) # or other-shell equiv...
   ?    ranlib $i
   ?    # or, on some machines: ar s $i
   ? end
   

   We'd be interested to know if this is still necessary.

10. If you end up making documents that involve (La)TeX and/or `tib' (Simon's favourite), the odds are that something about your/our setup will reach out and bite you. Yes, please complain; meanwhile, you can do `make -n whatever.dvi' to see the intended commands, then try to muddle through, doing them by hand.

11. GHC's sources go through `cpp' before being compiled, and `cpp' varies a bit from one Unix to another. One particular gotcha is macro calls like this:

      SLIT("Hello, world")
    

    Some `cpp's treat the comma inside the string as separating two macro arguments, so you get

      :731: macro `SLIT' used with too many (2) args
    

    Alas, `cpp' doesn't tell you the offending file! Workaround: don't put wierd things in string args to `cpp' macros.

10 Index

a

b

d

f

g

h

i

m

n

p

r

s

t

u

x

y

Footnotes

(1)

One of the most important features of GNU `make' that we use is the ability for a `Makefile' to include another named file, very like `cpp''s `#include' directive.

This document was generated on 3 December 1997 using the texi2html translator version 1.51.