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diff --git a/posts/2013-11-22-first-guile-patch.md b/posts/2013-11-22-first-guile-patch.md new file mode 100644 index 0000000..d67c786 --- /dev/null +++ b/posts/2013-11-22-first-guile-patch.md @@ -0,0 +1,150 @@ +title: First GNU Guile Patch and More Guix Packages +date: 2013-11-22 21:00 +tags: gnu, guix, scheme, guile, wsu +summary: I added alist->hash-table procedures for Guile’s native hash table implementation and packaged SDL libraries for Guix. +--- + +I have spent some of the last month working on contributing to GNU +Guile and now I can finally say that I have contributed code to the +project. Guile has several hash table implementations: a Guile native +one, SRFI-69, and R6RS. SRFI-69 contains a handy procedure, +`alist->hash-table`, which allows for a sort of hash literal-like +syntax: + +```scheme +(alist->hash-table + '((foo . 1) + (bar . 2) + (baz . 3))) +``` + +However, I prefer to use Guile’s native hash implementation, and +SRFI-69 is incompatible with it, so I decided to port +`alist->hash-table`. Unfortunately, it was not as simple as writing +just one procedure. The native hash tables actually have 4 different +ways of doing key comparisons: Using `equal?`, `eq?`, `eqv?`, and +user-defined procedures. This is a design flaw because the user must +make sure to use the right procedures at all times rather than simply +set the `hash` and `assoc` procedures when creating the hash table +instance. + +Below is the final implementation. Since 3 of the 4 variations were +essentially the same, I wrote a short macro to reduce code +duplication. + +```scheme +;;;; Copyright (C) 2013 Free Software Foundation, Inc. +;;;; +;;;; This library is free software; you can redistribute it and/or +;;;; modify it under the terms of the GNU Lesser General Public +;;;; License as published by the Free Software Foundation; either +;;;; version 3 of the License, or (at your option) any later version. +;;;; +;;;; This library is distributed in the hope that it will be useful, +;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of +;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +;;;; Lesser General Public License for more details. +;;;; +;;;; You should have received a copy of the GNU Lesser General Public +;;;; License along with this library; if not, write to the Free Software +;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA +;;;; + +(define-syntax-rule (define-alist-converter name hash-set-proc) + (define (name alist) + "Convert ALIST into a hash table." + (let ((table (make-hash-table))) + (for-each (lambda (pair) + (hash-set-proc table (car pair) (cdr pair))) + (reverse alist)) + table))) + +(define-alist-converter alist->hash-table hash-set!) +(define-alist-converter alist->hashq-table hashq-set!) +(define-alist-converter alist->hashv-table hashv-set!) + +(define (alist->hashx-table hash assoc alist) + "Convert ALIST into a hash table with custom HASH and ASSOC +procedures." + (let ((table (make-hash-table))) + (for-each (lambda (pair) + (hashx-set! hash assoc table (car pair) (cdr pair))) + (reverse alist)) + table)) +``` + +Not only did I manage to get my code into Guile, I was given commit +access to GNU Guix by the lead developer, Ludovic Courtès. I have +never had commit access to any free software project repositories +besides my own. I feel quite honored, as cheesy as that may sound. + +Packages for SDL and SDL2 have been merged into master, and packages +for SDL_gfx, SDL_image, SDL_mixer, SDL_net, and SDL_ttf for SDL 1.2 +are pending review. + +I like to show off the elegance of Guix package recipes, so here’s +some code: + +```scheme +;;; Copyright © 2013 David Thompson <dthompson2@worcester.edu> +;;; +;;; This file is part of GNU Guix. +;;; +;;; GNU Guix is free software; you can redistribute it and/or modify it +;;; under the terms of the GNU General Public License as published by +;;; the Free Software Foundation; either version 3 of the License, or (at +;;; your option) any later version. +;;; +;;; GNU Guix is distributed in the hope that it will be useful, but +;;; WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +;;; GNU General Public License for more details. +;;; +;;; You should have received a copy of the GNU General Public License +;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. + +(define sdl + (package + (name "sdl") + (version "1.2.15") + (source (origin + (method url-fetch) + (uri + (string-append "http://libsdl.org/release/SDL-" + version ".tar.gz")) + (sha256 + (base32 + "005d993xcac8236fpvd1iawkz4wqjybkpn8dbwaliqz5jfkidlyn")))) + (build-system gnu-build-system) + (arguments '(#:tests? #f)) ; no check target + (inputs `(("libx11" ,libx11) + ("libxrandr" ,libxrandr) + ("mesa" ,mesa) + ("alsa-lib" ,alsa-lib) + ("pkg-config" ,pkg-config) + ("pulseaudio" ,pulseaudio))) + (synopsis "Cross platform game development library") + (description "Simple DirectMedia Layer is a cross-platform development +library designed to provide low level access to audio, keyboard, mouse, +joystick, and graphics hardware.") + (home-page "http://libsdl.org/") + (license lgpl2.1))) + +(define sdl2 + (package (inherit sdl) + (name "sdl2") + (version "2.0.0") + (source (origin + (method url-fetch) + (uri + (string-append "http://libsdl.org/release/SDL2-" + version ".tar.gz")) + (sha256 + (base32 + "0y3in99brki7vc2mb4c0w39v70mf4h341mblhh8nmq4h7lawhskg")))) + (license bsd-3))) +``` + +Much help is needed to package the GNU system for Guix. If you are +interested in helping, please drop by `#guix` on freenode, we are +friendly. :) |