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This is the source code distribution for PLT Scheme (MzScheme and/or
MrEd with DrScheme). For license information, please see the file

Compiled binaries, documentation, and up-to-date information are
available at

The MzScheme and MrEd source code should compile and execute on
Windows, Mac OS X, or any Unix/X platform (including Linux).

Per-platform instructions are below.

Please report bugs via one of the following:
  - Help Desk's "submit bug report" link  (preferred)
  -                   (last resort)


 Compiling for Windows

To compile with Microsoft Visual C, read the instructions in

To compile with Cygwin tools, follow the Unix instructions below, and
be sure to configure with --enable-shared. The result is a Unix-style
build, not a Windows-style build (e.g., MzScheme's `system-type'
procedure returns 'unix, not 'windows, and MrEd uses X11).

 Compiling for Mac OS X

First, install the Mac OS X Developer Tools from Apple. Then, follow
the Unix instructions below, but note the following:

 * The MzScheme build creates a framework, PLT_MzScheme.framework,
   which is installed into plt/lib. This framework is used by the
   executable `mzscheme' that goes into plt/bin.

 * The MrEd build creates a framework, PLT_MrEd.framework, which is
   installed into plt/lib. This framework is used by the executable
   bundle that goes into the `plt' directory.  Installation
   creates a script, plt/bin/mred, that runs the bundle.

 * The --enable-shared flag for `configure' is redundant (i.e., builds
   create and use frameworks by default), and --disable-shared is not

 * To build an X11-based MrEd, run `configure' with the --enable-xonx
   flag. Frameworks are not used for such builds. The --enable-xonx
   flag also affects the MzScheme build so that `system-type' reports

 Compiling for supported Unix variants (including Linux) or Cygwin

 0. If you have an old PLT installation in the target directory,
    remove it (unless you are using Subversion with an "in-place"
    build as described below).

    Also, make sure that you have libraries and header files for Xft
    and Cairo (v1.23 and up) if you would like support for font
    smoothing (Xft) and graphics smoothing (Cairo). These libraries
    are not distributed with PLT Scheme. The configure process checks
    automatically whether these libraries are available.

    OpenGL support for MrEd sometimes requires special configuration
    (though generally not under Linux). See the note at the end of
    this section if OpenGL fails to work.

    Finally, the content of the "foreign" subdirectory may require GNU
    `make'. If the build fails with another variant of `make', please
    try using GNU `make'.

 1. Run the script `configure' (which is in the same directory as this
    README), usually with a --prefix=TARGETDIR command-line argument
    and optionally with --enable-shared.

    For example, if you want to install into /usr/local/plt using
    dynamic libraries, then run

        [here]configure --prefix=/usr/local/plt --enable-shared

    where "[here]" is the directory path containing the `configure'
    script (possibly unnecessary, or possibly just "./", depending on
    your shell and PATH setting).

    If the --prefix flag is omitted, the binaries are built for an
    in-place installation (i.e., the parent of the directory
    containing this README will be used directly). Unless
    --enable-shared is used, the plt directory can be moved later;
    most system administrators would recommend that you use
    --enable-shared, but the PLT Scheme developers distribute binaries
    built without --enable-shared.

    The `configure' script generates the makefiles for building
    MzScheme and/or MrEd. The current directory at the time
    `configure' is run will be used as working space for building the
    executables (independent of --prefix). This build directory does
    not have to be in the source tree, even for an "in-place"
    build. It's ok to run `configure' from its own directory (as in
    the example above), but it's often better to pick a separate build
    directory that is otherwise empty.

    The `configure' script accepts many other flags that adjust the
    build process. Run `configure --help' for more information. In
    addition, a specific compiler can be selected through environment
    variables. For example, to select the SGI compilers for Irix
    instead of gcc, run configure as

         env CC=cc CXX=CC [here]configure

    For cross compilation, set the compiler variables to a compiler
    for the target platform compiler, but also set CC_FOR_BUILD to a
    compiler for the host platform (for building binaries to execute
    during the build process). If the target machine's stack grows up,
    you'll have to supply --enable-stackup; if the target machine is
    big-endian, you may have to supply --enable-bigendian.

    If you re-run `configure' after running `make', then products of
    the `make' may be incorrect due to changes in the compiler command
    line. To be safe, run `make clean' each time after running

    When building for multiple platforms or configurations out of the
    same source directory, beware of cached `configure' information in
    `config.cache'. Avoid this problem entirely by using a separate
    build directory (but the same source) for each platform or

 2. Run `make'. [As noted in step 0, this must be GNU `make'.]

    With Cygwin, you may need to use `make --unix'.

    Binaries and libraries are placed in subdirectories of the build
    directory. For example, the `mzscheme' binary appears in the
    `mzscheme' directory.

 3. Run `make install'.

    This step copies binaries and libraries into place within the
    target installation. For example, the `mzscheme' binary is copied
    into the "bin" directory for an in-place build, or into the
    executable directory for a --prefix build.

    For a --prefix build, this step also creates a "" module
    in a "config" collection, so that various PLT tools and libraries
    can find the installation directories. At this stage, in case you
    are packaging an installation instead of installing directly, you
    can redirect the installation by setting the "DESTDIR" environment
    variable. For example, `make DESTDIR=/tmp/plt-build install'
    places the installation into "/tmp/plt-build" instead of the
    location originally specified with --prefix. The resulting
    installation will not work, however, until it is moved to the
    location originally specified with --prefix.

    Finally, the `make install' step compiles ".zo" bytecode files for
    installed Scheme source, and generates launcher programs like
    "DrScheme". Use `make plain-install' to install without compiling
    ".zo" files or creating launchers.

    If the installation fails because the target directory cannot be
    created, or because the target directory is not the one you
    wanted, then you can run `configure' again with a new --prefix
    value, then try step 3 again. After changing the --prefix value,
    it is sometimes not necessary to repeat steps 1 or 2. (Try it and
    find out...)

    If you build frequently from the Subversion-based sources, beware
    that you may accumulate user- and version-specific information in
    your "add-ons" directory, which you can most easily find by
      (find-system-path 'addon-dir)
    in MzScheme. In addition, if you configure with --enabled-shared,
    you may accumlate many unused versions of the dynamic libraries in
    your installation target.

 4. [Optional] Run `help-desk' to install missing documentation.

    The source distribution (or Subversion-based source) includes only
    the release notes, and not the rest of the core documentation.
    Run the newly installed `help-desk' and follow the "Manuals" link
    to install the rest of the documentation. For a Subversion-based
    build, the "Manuals" page includes a link to update previously
    installed documentation.

After an "in-place" install without Subversion, the plt/src directory
is no longer needed, and it can be safely deleted. Build information
is recorded in a "buildinfo" file in the installation.

For a build without --prefix (or with --enable-origtree) and without
--enable-shared, you can safely move the install tree, because all
file references within the installation are relative.

OpenGL, Unix, and pthreads

On some Unix systems, programs that use the OpenGL library must also
link to pthreads. To use MrEd's OpenGL support on these systems, MrEd
must be configured with the --enable-pthread option. Unfortunately,
MzScheme's normal stack handling and use of signals (for its own
thread scheduling) do not interact well with pthreads. Thus, when
pthreads are enabled, MzScheme and MrEd cannot use interupt timers,
and the stack is limited to 1MB. These restrictions can degrade
performance and thread-responsiveness.

If `configure' detects that OpenGL requires -lpthread for linking,
and if --enable-pthread is not specified, `configure' prints a warning
and disables GL support. On some systems, including at least FreeBSD
with the MESA GL implementation (but not the NVIDIA implementation,
which does not need pthreads), `configure' cannot detect the need for
pthreads. On these platforms, GL support will be included in MrEd,
but it will not work properly unless --enable-pthread is specified.

 Embedded Paths in the Executables

On all platforms, the MzScheme and MrEd binaries embed a path to the
main "collects" directory of library collections. This path can be
relative to the executable. Multiple paths can be provided, in which
case the first path is the main "collects" path, and additional paths
are placed before the main path (but after a user-specific "collects"
path) in the default collection path list.

The paths are embedded in the binary immediately after a "coLLECTs
dIRECTORy:" tag. Each path must be NUL terminated, the entire list of
paths must end with an additional NUL terminator, and the overall list
must be less than 1024 bytes long.

As an alternative to editing an exeuctable directly, the
`create-embedding-executable' procedure from `(lib ""
"compiler")' can be used to change the embedded path. For example, the
following program clones the MzScheme executable to "/tmp/mz" and
changes the embedded path in the clone to "/tmp/collects":

 (require (lib "" "compiler"))
 (create-embedding-executable "/tmp/mz" #:collects-path "/tmp/collects")

Similarly, `mzc' in `--exe' or `--gui-exe' mode accepts a `--collects'
flag to set the collection path in the generated executable.

Under Windows, executables also embed a path to DLLs. For more
information, see worksp\README.

Paths to all other installation directories are found through the
"" library of the "config" collection. See "doc.txt" in the
"config" collection (for search for "" in Help Desk) for more

 Compiling the OSKit-based Kernel

To build the OSKit-based MzScheme kernel, run the configure script
with the --enable-oskit or --enable-smalloskit flag. The result of
compiling will be `mzscheme.multiboot' in the `mzscheme' build
directory. It is a kernel in multiboot format.

Before building the MzScheme kernel, you must first install OSKit,
which is available from the Flux Research Group at Utah:

By default, configure assumes that OSKit is installed in
/usr/local. To specify a different location for OSKit, define the
OSKHOME environment variable.

For simplicity, the MzScheme kernel uses SGC rather than Boehm's
conservative garbage collector.

The --enable-smalloskit configuration produces a kernel without
networking or filesystem support. The kernel created by
--enable--oskit accepts filesystem and networking configuration
information on its multiboot command line via the --fs and --net

  --fs <drive> <partition> : mounts the given partition as the root
   directory. For example, to mount the seventh parition on main disk,
   supply: --fs hda f. Many filesystem formats are supported,
   including EXT2, MSDOS, and VFAT (all of the ones supported by
   Linux; see OSKit for details). The standard kernel can only mount
   one filesystem per run; hack main.c to get more.

  --net <address> <netmask> <gateway> : initializes ethernet support
   for MzScheme's TCP primitives. Example: --net Many types of ethernet cards are
   supported (the ones supported by FreeBSD; see OSKit for details).

Each of --fs and --net should be used once at most. The --fs and --net
flags must appear before any other command-line arguments, which are
handled by MzScheme in the usual way.

To access a filesystem or the network from non-multiboot kernels
(e.g., a LILO-compatible kernel), you must hardwire filesystem and
networking parameters in when compiling the kernel; see for details (grep for `hardwire').

 Porting to New Platforms

At a mininum, to port MzScheme to a new platform, edit
mzscheme/sconfig.h to provide a platform-specific compilation
information. As dsitributed, mzscheme/sconfig.h contains
configurations for the following platforms:

              Mac OS X
              Linux (x86, PPC, 68k, Alpha)
              Solaris (x86, Sparc)
              SunOS4 (Sparc)
              IBM AIX (RS6000)
              SGI IRIX (Mips)
              DEC Ultrix
              OSF1 (Alpha)
              SCO Unix (x86)

If your platfrom is not supported by the Boehm garbage collector
(distributed with PLT source), provide the `--enable-sgc' flag to

 Additional Compilation Notes

Garbage Collector

The conservative garbage collector distributed with MzScheme (in the
gc directory) has been modified slightly from Boehm's standard
distribution. Mostly, the change modify the way that object
finalization is handled.

Precise GC

MzScheme and MrEd can be compiled to an experimental form that uses a
mmemory-moving garbage collector with precise tracking of pointers (as
opposed to "conservation garbage collection"). The experimental forms
are called MzScheme3m and MrEd3m, repsectively, where the "3m" stands
for "moving memory manager".

* Building for Unix and Mac OS X

  Run `make 3m'. Building MzScheme3m and MrEd3m first builds the
  normal MzScheme and MrEd executables, then uses them to build the 3m
  versions. Run `make install-3m' to install the 3m binaries.

  Note on OS X (actually, PowerPC and gcc): gcc version 2.x has an
  optimizer bug that prevents 3m from building. Either use gcc 3.x or
  supply --disable-opt to `configure'.

* Windows

  Build and install the normal MzScheme and MrEd executables using
  Micsrosoft Visual C, and make sure that cl.exe is in your shell
  path. Then, in a shell, change directories to plt\src\worksp\gc2 and

   ..\..\..\mzscheme.exe -r

  The resulting MzScheme3m.exe and MrEd3m.exe will appear in the "plt"
  directory, along with DLLs libmzsch3mxxxxxxx.dll and
  libmred3mxxxxxxx.dll in plt/lib. (There is no correspingd
  libmzgc3mxxxxxxx.dll.  Instead, it is merged with

Configuration Options

By default, MzScheme is compiled without support for single-precision
floating point numbers. This and other options can be modified by
setting flags in mzscheme/sconfig.h.

Modifying MzScheme

If you modify MzScheme and change any primitive syntax or the
collection of built-in identifers, be sure to turn off
USE_COMPILED_MACROS in schminc.h. Otherwise, MzScheme won't start.
See schminc.h for details.
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