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  README file for the CHICKEN Scheme system
  =========================================


  (c) 2008-2021, The CHICKEN Team
  (c) 2000-2007, Felix L. Winkelmann

  version 5.2.1


 1. Introduction

        CHICKEN is a Scheme-to-C compiler supporting the language
        features as defined in the 'Revised^5 Report on
        Scheme'. Separate compilation is supported and full
        tail-recursion and efficient first-class continuations are
        available.

        Some things that CHICKEN has to offer:

        1. CHICKEN generates quite portable C code and compiled files
           generated by it (including itself) should work without any
           changes on Windows, most UNIX-like platforms, and with
           minor changes on other systems.

        2. The whole package is distributed under a BSD style license
           and as such is free to use and modify as long as you agree
           to its terms.

        3. Linkage to C modules and C library functions is
           straightforward. Compiled programs can easily be embedded
           into existing C code.

        4. Loads of extra libraries.

        Note: Should you have any trouble in setting up and using
        CHICKEN, please ask questions on the CHICKEN users mailing
        list.  Check http://wiki.call-cc.org/discussion-groups for
        information on how to subscribe to CHICKEN mailing lists.


 2. Installation

        Building CHICKEN requires GNU Make. Other "make" derivates are
        not supported. If you are using a Windows system and do not
        have GNU Make, download
        http://www.call-with-current-continuation.org/tarballs/UnxUtils.zip.
        It contains a precompiled set of UNIX utilities, which among
        other useful tools contains "make".

        Configuration and customization of the build process is done by 
        either setting makefile variables on the "make" command line or 
        by editing the platform-specific makefile.

    2.1. Building from a release tarball

        To build CHICKEN, first extract the archive ("tar xzf
        chicken-<version>.tar.gz" on UNIX or use your favorite
        extraction program on Windows), then change to the
        chicken-<version> directory and invoke "make" like this:

            make PLATFORM=<platform> PREFIX=<destination>

        where "PLATFORM" specifies on what kind of system CHICKEN
        shall be built and "PREFIX" specifies where the executables
        and libraries shall be installed. Out-of-directory builds are
        currently not supported, so you must be in the toplevel source
        directory to invoke "make".

        If you enter "make" without the PLATFORM option, CHICKEN will
        attempt to figure out what platform you are using. If it cannot
        do so, you will see a list of supported platforms. If you are
        cross-building, you must specify PLATFORM; for example,
        PLATFORM=cross-linux-mingw will build CHICKEN on Linux to
        deploy on Windows.

        If CHICKEN somehow detects the wrong platform, type

            make PLATFORM=""

        to get a list of available platforms, and re-run "make" using
        the correct platform.

	Note that parallel builds (using the "-j" make(1) option) are
	*not* supported.

        If you invoke "make" later with different configuration parameters,
        it is advisable to run:

            make confclean

        to remove old configuration files.

    2.2. Building from Git

        If you build CHICKEN directly from the development sources out
        of the git repository, you will need a "chicken" executable to
        generate the compiled C files from the Scheme library sources.
        See section 2.1 for platform detection issues.

        If you are building in a checkout where you have built other
        versions of chicken, you need to make sure that all traces of
        the previous build are removed. "make clean" is insufficient,
        and you should do the following:

            make spotless

        You will need to have a "chicken" binary installed, ideally
        from the development snapshot tarball that is closest to the
        git version you are trying to build (significantly older or
        newer ones are unlikely to work), and then use that chicken
        to build from your git sources.  Installing this CHICKEN is
        recommended, if necessary you can install it to a temporary
        location in your homedir for example.

        Then, to build you can run:

            make CHICKEN=<install-dir>/bin/chicken

        In some cases, the sources may have diverged enough to
        become unbuildable even with the snapshot.  Then you'll need
        to first build a bootstrapping compiler with the installed
        CHICKEN and then use that to build the version from git.
        See the "Bootstrapping" section below.

    2.3. Finishing the installation

        If CHICKEN is built successfully, you can install it on your
        system by entering

            make PREFIX=<destination> install

        "PREFIX" defaults to "/usr/local". Note that the PREFIX is
        compiled into several CHICKEN tools and must be the same
        while building the system and during installation.

        To install CHICKEN for a particular PREFIX on a different
        location, set the "DESTDIR" variable in addition to "PREFIX":
        It designates the directory where the files are installed
        into.

    2.4. Verifying your installation is correct

        You can check whether CHICKEN is functioning correctly by
        running

            make <vars> check

        where <vars> are all the variables you used while building
        CHICKEN.

        This will run the test scripts, which show a lot of output.
        The only thing that matters is the exit status at the end.
        If it exits with status 0, everything is fine, if it exits
        with a nonzero status, the failing test's output should be
        the final lines before Make's "error; exit" output.  If the
        check fails on unmodified sources, please file a bugreport.

    2.5. Optional features

        You can further enable various optional features by adding
        one or more of the following variables to the "make"
        invocation:

        DEBUGBUILD=1
          Disable optimizations in compiled C code and enable
          debug information.

        STATICBUILD=1
          Build only static versions of the runtime library, compiler
          and interpreter.

        EXTRA_CHICKEN_OPTIONS=...
          Additional options that should be passed to `chicken' when
          building the system.

        C_COMPILER_OPTIMIZATION_OPTIONS=...
          Override built-in C compiler optimization options. Available
          for debug or release build.

        PROGRAM_PREFIX= 
          A prefix to prepend to the names of all generated executables. 
          This allows having multiple CHICKEN versions in your PATH 
          (but note that they have to be installed at different locations).

        PROGRAM_SUFFIX=
          A suffix to be appended to the names of all generated executables.

        HOSTSYSTEM=
          A "<machine>-<platform>" name prefix to use for the C compiler to
          use to compile the runtime system and executables. Set this variable
          if you want to compile CHICKEN for a different architecture than
          the one on which you are building it.

        TARGETSYSTEM= 
          Similar to "HOSTSYSTEM", but specifies the name
          prefix to use for compiling code with the "csc" compiler
          driver. This is required for creating a "cross chicken", a
          specially built CHICKEN that invokes a cross C compiler to
          build the final binaries. You will need a cross compiled
          runtime system by building a version of CHICKEN with the
          "HOST" option mentioned above. More information about this
          process and the variables that you should set are provided
          in the manual (see the "Cross development" chapter).

        SRCDIR= 
          Specifies that CHICKEN should be built outside of its source
          tree. The SRCDIR variable indicates the location of the
          CHICKEN source tree. The executables and object files will
          be generated in the current directory.

	VARDIR=
	  If set, this directory overrides the location where
	  extensions along with their metadata are stored. Normally
	  this will be equivalent to "<PREFIX>/lib/chicken/<BINARYVERSION>".
	  When VARDIR is specified, extensions will be stored in
	  "<VARDIR>/chicken/<BINARYVERSION>", conforming to the FHS.

	CONFIG=
	  If you build CHICKEN often, passing all those make variables
	  can get annoying. An alternative is to create a configuration
	  file defining the required variables and passing 
          "CONFIG=<configfile>" to make(1).
          Even simpler is editing the included "config.make"
	  and just invoke make(1) without any extra parameters.

        C_COMPILER=
	  You can select an alternative compiler by setting this variable.
	  The default compiler is "gcc". CHICKEN can be built with the
	  LLVM version of gcc and with "clang", the LLVM-based C compiler,
	  just set C_COMPILER to "llvm-gcc" or "clang".

        LINKER=
	  Selects the linker to be used for creating executables and 
	  dynamic libraries from compiled C code. This should normally
	  be the same as C_COMPILER.

	PROFILE_OBJECTS=
	  This variable allows you to profile (parts of) CHICKEN itself.
	  Just pass in a whitespace-separated list of objects, without
	  the .scm-extension.  (An "object" here is an individual
	  .scm-file which gets compiled to a .c-file)
	  To build with profiling support, run "make spotless" first.
	  Be warned that this is a highly experimental option and
	  profiling doesn't work for every component of CHICKEN.

    2.6. Uninstalling CHICKEN

        To remove CHICKEN from your file-system, enter (probably as
        root):

            make PREFIX=<destination> uninstall

        (If you gave DESTDIR during installation, you have to pass
        the same setting to "make" when uninstalling)

    2.7. What gets installed

	These files will be installed under the prefix given during
	build and installation:

        <PREFIX>
	|-- bin
	|   |-- chicken
	|   |-- chicken-install
	|   |-- chicken-profile
	|   |-- chicken-status
	|   |-- chicken-uninstall
 	|   |-- libchicken.dll                        (Windows)
	|   |-- csc
	|   |-- csi
	|   |-- feathers.bat                          (Windows)
	|   `-- feathers                              (Unix)
	|-- include
	|   `-- chicken
	|       |-- chicken-config.h
	|       `-- chicken.h
	|-- lib
	|   |-- chicken
	|   |   `-- 9
	|   |       |-- chicken.base.import.so
	|   |       |-- chicken.bitwise.import.so
	|   |       |-- chicken.blob.import.so
	|   |       |-- chicken.compiler.user-pass.import.so
	|   |       |-- chicken.condition.import.so
	|   |       |-- chicken.continuation.import.so
	|   |       |-- chicken.csi.import.so
	|   |       |-- chicken.errno.import.so
	|   |       |-- chicken.eval.import.so
	|   |       |-- chicken.file.import.so
	|   |       |-- chicken.file.posix.import.so
	|   |       |-- chicken.fixnum.import.so
	|   |       |-- chicken.flonum.import.so
	|   |       |-- chicken.foreign.import.so
	|   |       |-- chicken.format.import.so
	|   |       |-- chicken.gc.import.so
	|   |       |-- chicken.internal.import.so
	|   |       |-- chicken.io.import.so
	|   |       |-- chicken.irregex.import.so
	|   |       |-- chicken.keyword.import.so
	|   |       |-- chicken.load.import.so
	|   |       |-- chicken.locative.import.so
	|   |       |-- chicken.memory.import.so
	|   |       |-- chicken.memory.representation.import.so
	|   |       |-- chicken.pathname.import.so
	|   |       |-- chicken.platform.import.so
	|   |       |-- chicken.plist.import.so
	|   |       |-- chicken.port.import.so
	|   |       |-- chicken.pretty-print.import.so
	|   |       |-- chicken.process.import.so
	|   |       |-- chicken.process.signal.import.so
	|   |       |-- chicken.process-context.import.so
	|   |       |-- chicken.process-context.posix.import.so
	|   |       |-- chicken.random.import.so
	|   |       |-- chicken.repl.import.so
	|   |       |-- chicken.sort.import.so
	|   |       |-- chicken.string.import.so
	|   |       |-- chicken.read-syntax.import.so
	|   |       |-- chicken.syntax.import.so
	|   |       |-- chicken.tcp.import.so
	|   |       |-- chicken.time.import.so
	|   |       |-- chicken.time.posix.import.so
	|   |       |-- modules.db
	|   |       |-- srfi-4.import.so
	|   |       `-- types.db
	|   |-- libchicken.a
	|   |-- libchicken.dll.a                      (Windows)
	|   |-- libchicken.dylib                      (Macintosh)
	|   |-- libchicken.so -> libchicken.so.9      (Unix)
	|   `-- libchicken.so.9                       (Unix)
	`-- share
	    |-- chicken
	    |   |-- doc
	    |   |   |-- LICENSE
	    |   |   |-- README
	    |   |   |-- DEPRECATED
	    |   |   |-- mac.r                         (Macintosh)
	    |   |   |-- CHICKEN.icns                  (Macintosh)
	    |   |   |-- manual-html
	    |   |   |-- chicken.png
	    |   |   |-- feathers.tcl
	    |   |   `-- *.html
	    |   `-- setup.defaults
	    `-- man
		`-- man1
		    |-- chicken-install.1
		    |-- chicken-profile.1
		    |-- chicken-status.1
		    |-- chicken-uninstall.1
		    |-- chicken.1
		    |-- csc.1
		    |-- csi.1
		    `-- feathers.1


 3. Usage

        Documentation can be found in the directory
        PREFIX/share/chicken/doc in HTML format. The manual is
        maintained in a wiki at http://wiki.call-cc.org. Go there to
        read the most up to date documentation.


 4. Extensions

        A large number of extension libraries for CHICKEN are
        available at http://wiki.call-cc.org/eggs. You can
        automatically download, compile and install extensions with
        the "chicken-install" program. See the CHICKEN User's Manual
        for more information.

        A selection of 3rd party libraries, together with source and
        binary packages for tools helpful for development with CHICKEN
        are also available at:
        <http://www.call-with-current-continuation.org/tarballs/>.

        
 5. Platform issues

        Android:
     
	  - The Android SDK and NDK are required. Make sure you have
	    set up a project and have a suitable NDK toolchain
	    available. You will have to override the make(1) variable
	    C_COMPILER to contain the correct compiler; see
	    docs/STANDALONE-TOOLCHAIN.html in your NDK root for notes
	    on how to call the correct compiler. You will also need to
	    override the ARCH variable to match the device you're
	    targeting.  The build will produce a libchicken.so that
	    can then be integrated into your project as a prebuilt
	    shared library.  See the android section on
	    http://wiki.call-cc.org/embedding for a complete example.

	  - It is possible to use eggs, by copying them into the right
	    place and probably renaming the files. This is somewhat
	    awkward and requires various hacks to make the
	    loading/linking of eggs work. It may be easier to build
	    the eggs you need manually and linking them statically to
	    your executable.

	  - By default debug-logging is enabled and written to the
	    Android log.

    	FreeBSD/NetBSD/OpenBSD:

          - *BSD system users *must* use GNU make ("gmake") - the makefiles
            can not be processed by BSD make.

	  - On NetBSD it might be possible that compilation fails with a
	    "virtual memory exhausted error".  Try the following:

	    % unlimit datasize

	  - When using -deploy on NetBSD, currently the kernel only
	    supports running the program through its absolute path,
	    otherwise you will get an error message stating:

	      execname not specified in AUX vector: No such file or directory

	    Deployed binaries can also be run without an explicit path,
	    through $PATH; only relative pathnames do not work.

	  - Using external libraries on NetBSD may also be easier, if
	    you add the following definitions to `Makefile.bsd':

	      C_COMPILER_OPTIONS += -I/usr/pkg/lib
	      LINKER_OPTIONS += -L/usr/pkg/lib -Wl,-rpath=/usr/pkg/lib

	    Note that this may cause build-problems, if you already have
	    an existing CHICKEN installation in the /usr/pkg prefix.

        Linux:

	  - If you want to build Linux binaries which use the "X32 ABI",
	    you can pass ARCH=x32 on the Make command line.

          - There have been reports where the library directory
	    "/usr/lib64" could not be found at build-time on a Fedora
	    12 system. If you build a 64-bit version of CHICKEN and
	    the library directory is set incorrectly, you can override
	    it by passing "LIBDIR=/usr/lib64" as an additional
	    argument when you invoke "make".

        Solaris:

	  - By default, CHICKEN is build with the GNU C compiler (`gcc').
	    To use the SunPro C compiler (`cc') instead, pass

	      C_COMPILER=cc

	    to the "make" invocation.

	  - Older versions of Solaris have a bug in ld.so that causes
	    trouble with dynamic loading.  Patching Solaris fixes the
	    problem. Solaris 7 needs patch 106950-18. Solaris 8 has an
	    equivalent patch, 109147-16.

	    You can find out if you have these patches installed by
	    running:

	    % showrev -p | grep 106950    # solaris 7
	    % showrev -p | grep 109147    # solaris 8

	Mac OS X:

          - The build currently assumes the Xcode application path is
            "/Applications/Xcode.app/", with the C compiler and build
            tools being located in the "Contents/Developer/usr/bin"
            and
            "Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin"
            subdirectories, respectively. To override these locations,
            set XCODE_DEVELOPER and XCODE_TOOL_PATH on the make(3)
            command line.

	  - CHICKEN will normally select a 32-bit or 64-bit build
	    automatically when you use the normal build step:

	      make

	    Specifically, the defaults are:

	      10.4: 32-bit
	      10.5: 32-bit
	      10.6: 64-bit (32-bit on original Core Duo, circa early 2006)
	      10.7: 64-bit

	    On 10.5, you can optionally build in 64-bit mode on machines
	    released in late 2006 or later (i.e. with a Core 2 Duo or Xeon
	    CPU), by specifying ARCH=x86-64:

	      make ARCH=x86-64

	  - Universal binaries: On 10.4 and 10.5 only, CHICKEN and its eggs
	    can be built as universal binaries which will work on either
	    Intel or PowerPC.  Most users will not want to do this.

	    For 10.4 universal build:
	      make ARCH=universal

	    For 10.5 universal build:
	      export MACOSX_DEPLOYMENT_TARGET=10.4
	      make C_COMPILER=gcc-4.0 ARCH=universal

	    For 10.6 and later, universal builds are not supported.

	  - On 10.3 and earlier, you must first install `dlcompat'
	    which can be found at http://distfiles.macports.org/dlcompat/.


        iOS:

          - Make sure the "XCODE_PATH" setting is correct (see
            Makefile.ios), it defaults to "/Applications/Xcode.app".

          - The paths for the the various build tools changed between
            Xcode 4 and 5. The makefile used for iOS builds of CHICKEN
            assume Xcode 5 is used. If you are using Xcode 4, override
            the XCODE_TOOLPATH and C_COMPILER make-variables providing
            the correct paths, see Makefile.ios for suggestions.

          - The iOS build is static (iOS doesn't support dynamic
            loading of executable code). Only the runtime library
            (libchicken.a) is of interest. To use it, integrate
            libchicken.a in your Xcode project and use a normal MacOS
            build to compile your Scheme sources into C files, adding
            them to you project.

          - Core library units must by accessed via "(declare (uses
            ...))" and "(import ...)", "require", "require-library",
            "require-extension" and "use" will not work, due to the
            reasons mentioned above.

          - As dynamic loading is not supported, eggs can not be used
            as usual, you will have to compile them manually and
            integrate what you need into your project.

          - If you want to build for the iPhone Simulator, override
            the ARCH and XCODE_SDK variables accordingly, see also in
            Makefile.ios for suggestions.

   	Windows:

	  - On Windows, mingw32, <http://mingw.sourceforge.net/> and
	    Cygwin are supported (Microsoft Visual Studio is *NOT*).
	    Makefiles for mingw under MSYS and the Windows shell are
	    provided (`Makefile.mingw-msys' and `Makefile.mingw'). 
	    Please also read the notes below.

	  - When installing under the mingw-msys platform, PREFIX must be an
	    absolute path name (i.e. it must include the drive letter) and
	    must use forward slashes (no backward slashes), for example
            "PREFIX=C:/chicken/".

	  - When installing under mingw, with a windows shell
	    ("cmd.exe"), pass an absolute pathname (including the
	    drive letter) as PREFIX and use forward slashes. If you
	    are building the sources from git, use backslashes to
	    specify the path to `chicken' (the "CHICKEN" variable).

	  - When installing under mingw without MSYS, make sure that the
	    MSYS tools (in case you have some of them, in particular the
	    sh.exe UNIX shell) are *NOT* visible in your PATH.

	  - 64-bit Windows is supported, invoke mingw32-make with the
	    "ARCH=x86-64" argument (this is currently not detected
	    automatically). The build has been tested on Windows 7
	    with the SJLJ binary package from "MinGW-builds", which
	    can be found here:

	    http://sourceforge.net/projects/mingwbuilds/

	  - Cygwin will not be able to find the chicken shared libraries
	    until Windows is rebooted.

	  - During "make check" you may see these intermittent errors:

	      ld.exe: cannot open output file a.out: Permission denied

	    When this happens, the virusscanner is holding open
	    the file of the previous test while the compiler is
	    preparing the next test.
	    To work around this in Windows Defender (the default),
	    disable "realtime protection" under tools->options.

	AIX:

	  - CHICKEN is built with the GNU C compiler (`gcc').  IBM's XL
	    C compiler is not supported at this time.

	  - AIX users *must* use GNU make ("gmake") - the makefiles can not be
	    processed with IBM's version of make.

	  - Deployment doesn't work.  See manual/Deployment for more details.

	  - The AIX linker may occasionally show warnings of the form:

	      ld: 0711-783 WARNING: TOC overflow. TOC size: 66656
	      Maximum size: 65536
	      Extra instructions are being generated for each reference to a TOC
	      symbol if the symbol is in the TOC overflow area.

	    Such messages indicate that lookups for some symbols in the
	    effected library/executable may be somewhat slower at runtime as an
	    auxiliary symbol table is needed to accommodate all of the symbols.

	  - The AIX assembler may show warnings of the form:

	      /tmp//ccycPGzK.s: line 527244: 1252-171 The displacement must be
	      greater than or equal to -32768 and less than or equal to 32767.

	    This is a known issue between the GNU toolchain and IBM's assembler:

	    http://gcc.gnu.org/bugzilla/show_bug.cgi?id=4587

	    The problem arises because the PPC architecture cannot perform jumps
	    to addresses that differ more than what a 16-bit integer can
	    represent.  Adding support for IBM's XL C compiler may resolve this
	    issue.

	    Instructing gcc to optimize the size of generated code (-Os)
	    mitigates this to some degree, but very large C files may still be
	    uncompilable.  This is known to affect the html-tags egg.

	Haiku:

	  - The default GCC compiler is too old to support the -fwrapv
	    option.  You can either remove the flag from Makefile.haiku,
	    use a newer GCC, or supply your own C_COMPILER_OPTIONS on
	    the Make command line.

	  - The default Haiku BFS file system only supports timestamps
	    with a granularity of one second.  This may cause trouble
	    with pregenerated release or development snapshot tarballs
	    due to the way files are pre-translated to C.  You'll either
	    need to have CHICKEN installed, or touch the
	    build-version.c file before building.


 6. Bootstrapping

        To build a bootstrapping compiler yourself, get the most
        recent development snapshot tarball from
        http://code.call-cc.org, unpack it, build and install it.
        Then change to the directory containing the git code and run:

            make CHICKEN=<path-to-existing-chicken> \
              boot-chicken

        This will produce a statically linked binary with the name
        "chicken-boot[.exe]" that can be given as the value of the
        "CHICKEN" argument when invoking make(1). Note that the path
        to an existing `chicken' binary must be given to use it for
        compiling the Scheme code of the runtime-system and compiler.

        "scripts/bootstrap.sh" automates this process; use this script
        if you are unsure how to build from the repository sources. It
        downloads the necessary development snapshot with wget(1) and
        builds the boot-chicken that you can use to compile the
        development sources. The invocation is:

            scripts/bootstrap.sh ...

        You can add additional parameters if you like to customize the
        build, but this should not be necessary. Note that your current
        working directory must be the root directory of the CHICKEN
        git(1) repository. Once the boot-chicken is built, proceed by
        invoking make(1) as described above (in 2.2, Building from Git),
        with the additional parameter:

            make CHICKEN=./chicken-boot ...


 7. Emacs support

        See http://wiki.call-cc.org/emacs for tips and links to emacs
	extensions for Scheme and CHICKEN programming.


 8. Compatibility notes

        In CHICKEN 4, the macro system has been reimplemented
	completely and provides module system, which has considerably
	more flexibility and power, but will require the
	re-implementation of macros in code that previously was used
	with CHICKEN 3. Notably, `define-macro' is not available
	anymore. See the manual on how to translate such macros to
	low-level hygienic macros or ask on the CHICKEN mailing list.


 9. What's next?

        If you find any bugs, or want to report a problem, please send
        a detailed bug report.

        If you have any more questions or problems (even the slightest
        problems, or the most stupid questions), then please subscribe
        to the "chicken-users"
        (http://lists.nongnu.org/mailman/listinfo/chicken-users)
        mailing list and ask for help. It will be answered.