├── .gitignore
├── LICENSE
├── README.md
└── cenv.scm


/.gitignore:
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 1 | *.so
 2 | *.import.scm
 3 | *.types
 4 | *.link
 5 | *.o
 6 | *.build.sh
 7 | *.install.sh
 8 | *~
 9 | *.swp
10 | 


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/LICENSE:
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 1 | MIT License
 2 | 
 3 | Copyright (c) 2021 Jim Ursetto
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


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/README.md:
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  1 | # cenv
  2 | 
  3 | Chicken 5 virtual environments.
  4 | 
  5 | ## Description
  6 | 
  7 | A single `csi` script, `cenv.scm`, which creates a self-contained Chicken 5 environment in a specified directory. It remembers which Chicken you used to create it, and it keeps its own repository of eggs, which extends that base Chicken.
  8 | 
  9 | When the environment is active, `csi` and `csc` and compiled programs use this repository, falling back to the base repository if an extension does not exist. `chicken-install` installs eggs into this new repository. `chicken-uninstall` is limited to the new repository, and `chicken-status` shows both. Generally, everything behaves as you expect.
 10 | 
 11 | `cenv` could be useful if:
 12 | 
 13 | - You are a regular user using the system Chicken and you have no permissions to, or don't want to, install eggs systemwide.
 14 | - You want to test or switch between different versions of eggs, without creating an entire Chicken installation to house them.
 15 | 
 16 | ## Usage
 17 | 
 18 | Initialize an environment by running `cenv.scm` with `csi`, using the `init` verb. The full path of the Chicken you use is permanently stored in the new environment (even if you don't call it with a full path).
 19 | 
 20 |     csi -s /path/to/cenv.scm init <directory>
 21 |     ~/mychicken/csi -s /path/to/cenv.scm init <directory>
 22 |     /path/to/cenv.scm init <directory>
 23 | 
 24 | Enter the environment by sourcing `center` (from bash), then running commands.
 25 | 
 26 |     source myenv/bin/center
 27 |     chicken-install ...
 28 | 
 29 | With `cexec` you can run a one-off command in the environment. It will use `/bin/sh`, so you can run it from a weird shell, such as fish.
 30 | 
 31 |     ./myenv/bin/cexec chicken-install ...
 32 | 
 33 | At the moment, there is no `cexit` to leave a `center`ed environment. You should start a subshell first if you need the ability to exit, or use `cexec`.
 34 | 
 35 | ## Example -- installing an egg
 36 | 
 37 | Nothing up my sleeve, `base64` is not installed:
 38 | 
 39 |     $ csi -R base64 -p '(base64-encode "hello")'
 40 |     Error: (import) during expansion of (import ...) - cannot import
 41 |     from undefined module: base64
 42 | 
 43 | Init environment in `~/tmp/myenv`:
 44 | 
 45 |     $ cd ~/tmp
 46 |     $ csi -s ~/scheme/cenv/cenv.scm init myenv
 47 |     Using CHICKEN 5.0.0 in /Users/jim/local/chicken/5.0.0
 48 |     Initializing repository in myenv
 49 |     New repository path:
 50 |     (/Users/jim/tmp/myenv/lib /Users/jim/local/chicken/5.0.0/lib/chicken/9)
 51 | 
 52 | Enter the new environment, and install `base64`:
 53 | 
 54 |     $ bash                       # Start a subshell
 55 |     $ source myenv/bin/center
 56 |     $ chicken-install base64
 57 |     building srfi-14
 58 |       installing srfi-14
 59 |     building srfi-13
 60 |       installing srfi-14
 61 |     building base64
 62 |       installing base64
 63 | 
 64 |     $ tree myenv/lib
 65 |     myenv/lib
 66 |     ├── base64.egg-info
 67 |     ├── base64.import.so*
 68 |     ├── base64.link
 69 |     ├── base64.o
 70 |     ├── base64.so*
 71 |     ├── srfi-13.egg-info
 72 |     ├── srfi-13.import.so*
 73 |     ├── srfi-13.link
 74 |     ├── srfi-13.o
 75 |     ├── srfi-13.so*
 76 |     ├── srfi-13.types
 77 |     ├── srfi-14.egg-info
 78 |     ├── srfi-14.import.so*
 79 |     ├── srfi-14.link
 80 |     ├── srfi-14.o
 81 |     ├── srfi-14.so*
 82 |     └── srfi-14.types
 83 | 
 84 | Run `base64` (still in the new environment):
 85 | 
 86 |     $ csi -R base64 -p '(base64-encode "hello")'
 87 |     aGVsbG8=
 88 | 
 89 | Exit the environment (subshell); `base64` no longer works:
 90 | 
 91 |     $ exit
 92 |     $ csi -R base64 -p '(base64-encode "hello")'
 93 |     Error: (import) during expansion of (import ...) - cannot import
 94 |     from undefined module: base64
 95 | 
 96 | Note that the `base64` dependencies `srfi-13` and `srfi-14` were installed in your repository as well. If you had them installed in your base Chicken, they would not be installed unless chicken-install deemed it necessary, for example to satisfy a version requirement.
 97 | 
 98 | ## Example -- two Chickens
 99 | 
100 | Initialize 2 environments, using 2 different versions of Chicken 5. `cexec` and `center` use the Chicken you initialized the environment with.
101 | 
102 |     $ ~/local/chicken/5.0.0/bin/csi -s ~/scheme/cenv/cenv.scm init c500
103 |     Using CHICKEN 5.0.0 in /Users/jim/local/chicken/5.0.0
104 |     Initializing repository in c500
105 |     New repository path:
106 |     (/Users/jim/tmp/c500/lib /Users/jim/local/chicken/5.0.0/lib/chicken/9)
107 | 
108 |     $ ~/local/chicken/5.0.1/bin/csi -s ~/scheme/cenv/cenv.scm init c501
109 |     Using CHICKEN 5.0.1 in /Users/jim/local/chicken/5.0.1
110 |     Initializing repository in c501
111 |     New repository path:
112 |     (/Users/jim/tmp/c501/lib /Users/jim/local/chicken/5.0.1/lib/chicken/10)
113 | 
114 | Run each version of chicken-install using `cexec` and check its version.
115 | 
116 |     $ ./c500/bin/cexec chicken-install -version
117 |     5.0.0
118 | 
119 |     $ ./c501/bin/cexec chicken-install -version
120 |     5.0.1
121 | 
122 | Alternatively you could use `center`:
123 | 
124 |     $ chicken-install -version          # default chicken in my PATH
125 |     4.12.0
126 | 
127 |     $ source c501/bin/center
128 |     $ chicken-install -version
129 |     5.0.1
130 | 
131 | ## Technical
132 | 
133 | Behind the scenes, `cenv` is just manipulating the environment variables `CHICKEN_INSTALL_PREFIX`, `CHICKEN_INSTALL_REPOSITORY`, `CHICKEN_REPOSITORY_PATH` and `PATH`.
134 | 
135 | ## Caveats and TODOs
136 | 
137 | - `cenv` extends the base Chicken's environment; the new environment is not completely isolated.
138 | - It would be possible to isolate the environment more by copying only a list of known base modules from the base repository into the new repository at initialization time, and omitting the base repository from the repo path.
139 | - Egg shared data may not be found inside a cenv, as (lacking support from the core) every egg hacks together a method of locating its shared data. Special action is taken in `center` to set the chicken-doc repository location correctly. If we turned `cenv` into a library, eggs could use it to standardize finding this data, and we could eliminate special casing.
140 | 


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/cenv.scm:
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  1 | #!/usr/bin/env csi -script
  2 | 
  3 | (import (chicken file)
  4 |         (chicken file posix)
  5 |         (chicken irregex)
  6 |         (chicken pathname)
  7 |         (chicken platform)
  8 |         (chicken process)
  9 |         (chicken process-context))
 10 | 
 11 | ;; kinda silly
 12 | (define (parse-args #!optional (args (command-line-arguments)))
 13 |   (when (null? args)
 14 |     (usage))
 15 |   (let ((verb (car args))
 16 |         (rest (cdr args)))
 17 |     `((command . ,(executable-pathname))
 18 |       (verb . ,(string->symbol verb))
 19 |       (args . ,rest))))
 20 | 
 21 | (define (usage)
 22 |   (print "usage: " (program-name) " init <dir>")
 23 |   (exit 1))
 24 | 
 25 | (define (dispatch)
 26 |   (let ((args (parse-args)))
 27 |     (let ((verb (alist-ref 'verb args)))
 28 |       (case verb
 29 |         ((init)
 30 |          (let ((args (alist-ref 'args args)))
 31 |            (when (null? args)
 32 |              (usage))
 33 |            (cenv-init-repository (car args))))
 34 |         (else
 35 |          (usage))))))
 36 | 
 37 | (define (template str alist)
 38 |   (irregex-replace/all "{{([A-Za-z0-9_-]+)}}"
 39 |                        str
 40 |                        (lambda (m)
 41 |                          (let ((key (string->symbol (irregex-match-substring m 1))))
 42 |                            (or (alist-ref key alist)
 43 |                                (error 'template "missing value for key" key))))))
 44 | 
 45 | ;; realpath is available as C_realpath but only if we compile.
 46 | (define (realpath x)
 47 |   (normalize-pathname
 48 |    (if (absolute-pathname? x)
 49 |        x
 50 |        (make-pathname (current-directory) x))))
 51 | (define (last x)
 52 |   (if (pair? (cdr x))
 53 |       (last (cdr x))
 54 |       (car x)))
 55 | 
 56 | ;; We precompute our env dir, the chicken prefix, and the chicken system repo; so we
 57 | ;; cannot relocate, but it makes things simpler.
 58 | ;; We may want to ignore any CHICKEN_REPOSITORY_PATH set in the calling environment;
 59 | ;; we currently honor it, which is of debatable utility.
 60 | (define center-data #<<EOF
 61 | #!/bin/bash
 62 | 
 63 | export CHICKEN_PREFIX="{{prefix}}"
 64 | export CHICKEN_ENV="{{env}}"
 65 | export CHICKEN_INSTALL_PREFIX=$CHICKEN_ENV
 66 | export CHICKEN_INSTALL_REPOSITORY=$CHICKEN_INSTALL_PREFIX/lib
 67 | export PATH=$CHICKEN_INSTALL_PREFIX/bin:$CHICKEN_PREFIX/bin:$PATH
 68 | export CHICKEN_REPOSITORY_PATH="$CHICKEN_INSTALL_REPOSITORY:{{sys-repo}}"
 69 | 
 70 | # chicken-doc repo defaults to being in system shared dir when unset;
 71 | # preserve this behavior for local envs.
 72 | if [ -z "${CHICKEN_DOC_REPOSITORY+x}" ]; then
 73 |    export CHICKEN_DOC_REPOSITORY=$CHICKEN_INSTALL_PREFIX/share/chicken-doc
 74 | fi
 75 | 
 76 | EOF
 77 | )
 78 | 
 79 | (define cexec-data #<<EOF
 80 | #!/bin/sh
 81 | 
 82 | . {{env}}/bin/center
 83 | exec "$@"
 84 | 
 85 | EOF
 86 | )
 87 | 
 88 | (define chicken-prefix
 89 |   ;; Note: If we compile, we can obtain prefix via foreign-variable, but
 90 |   ;;       it is not exposed by default. Otherwise, we just assume chicken-home
 91 |   ;;       is the default and reverse engineer the prefix.
 92 |   (let ((m (irregex-match "(.+)/share/chicken" (chicken-home))))
 93 |     (if m
 94 |         (irregex-match-substring m 1)
 95 |         (error "Unable to determine chicken prefix from " (chicken-home)))))
 96 | 
 97 | (define (create-cexec dirname)
 98 |   (let ((cexec (string-append dirname "/bin/cexec")))
 99 |     (with-output-to-file cexec
100 |       (lambda () (print (template cexec-data
101 |                              `((env . ,(realpath dirname)))))))
102 |     (set! (file-permissions cexec) #o0755)))    ; ignores umask, probably
103 | 
104 | (define (create-center dirname)
105 |   (let ((center (string-append dirname "/bin/center")))
106 |     (with-output-to-file center
107 |         (lambda () (print (template center-data
108 |                                `((prefix . ,chicken-prefix)
109 |                                  (env . ,(realpath dirname))
110 |                                  (sys-repo . ,(last (repository-path))))))))
111 |     (set! (file-permissions center) #o0644)))
112 | 
113 | (define (test-cenv dirname)
114 | ;; This is available in CHICKEN_REPOSITORY_PATH after entering environment,
115 | ;; but double-check that it works by running csi via cexec.
116 |   (print "New repository path:")
117 |   (system* (string-append (string-append dirname "/bin/cexec ")
118 |                           "csi -R chicken.platform -p '(repository-path)'")))
119 | 
120 | (define (cenv-init-repository dirname)
121 |   (print "Using CHICKEN " (chicken-version) " in " chicken-prefix)
122 |   (print "Initializing repository in " dirname)
123 |   (for-each (cut create-directory <> #t)
124 |             (map (cut string-append dirname <>)
125 |                  '("/bin" "/lib" "/share")))
126 |   (create-center dirname)
127 |   (create-cexec dirname)
128 |   (test-cenv dirname))
129 | 
130 | (dispatch)
131 | 


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