egg-layer

WARNING: this is a hack.

egg-layer is a tool that generates a Makefile to fetch and install CHICKEN eggs. Differently from chicken-install, it uses egg sources from tarballs available at [1]. egg-layer relies on external tools to fetch, verify and unpack tarballs. The default configuration uses wget, sha1sum, tar and gzip (parameters which use those commands are configurable -- see egg-layer-params.scm).

To generate the dependency graph for Makefile rules, egg-layer uses information from an index file [2] (gzip-compressed). The format of that file is:

• The first line is the index format version

• the next lines have the following format:

(EGG-NAME EGG-VERSION TARBALL-SIZE TARBALL-SHA1-SUM EGG-DEPENDENCIES EGG-TEST-DEPENDENCIES)

egg-layer downloads and reads the index file, determines the dependencies among eggs and tasks (fetch-tarball, fetch-checksum, unpack, install), and generates the Makefile.

Usage:

$ egg-layer -h
Usage: egg-layer [<options>] [<egg> ...]

If no egg is provided as argument, the current directory is assumed to be
the source directory of an egg.

<options>
  --action|-a <action>:
    Action to be executed (default: all).  Available actions:
    * all: install egg.
    * fetch: fetch egg and its dependencies.
    * none: only generate the Makefile.
    * unpack: fetch egg and its dependencies and unpack them.

  --config-file|-c <file>:
    Specify a configuration file alternative to the default one
    ($HOME/.egglayer.conf).

  --force-dependencies:
    Force processing actions for dependencies.  Without this option,
    actions for dependencies which are already installed will be skipped.

  --keep-output-directory|-k:
    By default, the output directory containing the Makefile generated by
    this program will be removed (unless --output-dir is provided).  With
    this option the the output directory is not removed.

  --output-dir|-o <dir>:
    Output directory (default: temporary directory with a random name)

  --parallel-tasks|-j <number>:
    The value of this parameter maps to the value of the -j parameter
    for make.  If given a negative value, -j for make will be given no
    value.

  --verbose:
    Print more information to the output.

• [1] https://code.call-cc.org/egg-tarballs/
• [2] https://code.call-cc.org/egg-tarballs/5/index.gz

Why

• Use egg tarballs

  • smaller size
  • integrity verification (HTTPS + checksum)

• Possibility of using the parallel execution feature of make to fetch and install eggs

Configuration

egg-layer loads $HOME/.egg-layer.conf if it exists. See egg-layer-params.scm for the possible configuration parameters.

Here's an example, which sets the parallelization option to the number of CPUs on a Linux system:

(import (chicken process))
(import egg-layer-params)

(parallel-tasks (with-input-from-pipe "nproc" read)

Alternatively, you can use the --config-file command line parameter to specify another file (in this case, $HOME/.egg-layer.conf will not be loaded).

Command line options clobber settings made in configuration files.

Bugs, limitations and assorted notes

• It has been very minimally tested on Linux with GNU make.

• No concern regarding portability.

• It uses chicken-install as build system for eggs (but not to fetch and verify integrity of sources).

• It completely ignores egg versions.

• It completely ignore egg tests.

• It supports only CHICKEN 5.

• Due to the way egg-layer uses chicken-install (cd egg-dir && chicken-install), it ends up not using the egg compilation cache.

• Its code is disgusting.

• It is just a very rough proof-of-concept. It is incomplete and probably full of bugs.