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Inhibit duplicates in fold-packages.

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* gnu/packages.scm (fold2): New procedure.
  (fold-packages): Rework to suppress duplicates.
This commit is contained in:
Mark H Weaver 2013-02-12 20:29:30 -05:00
parent 9011e97f8d
commit c2868b1e0c
1 changed files with 28 additions and 12 deletions
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40
gnu/packages.scm
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@ -1,5 +1,6 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013 Mark H Weaver <mhw@netris.org>
;;;
;;; This file is part of GNU Guix.
;;;
@ -20,6 +21,7 @@
#:use-module (guix packages)
#:use-module (guix utils)
#:use-module (ice-9 ftw)
#:use-module (ice-9 vlist)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-39)
@ -106,20 +108,34 @@
(false-if-exception (resolve-interface name))))
(package-files)))
(define (fold2 f seed1 seed2 lst)
(if (null? lst)
(values seed1 seed2)
(call-with-values
(lambda () (f (car lst) seed1 seed2))
(lambda (seed1 seed2)
(fold2 f seed1 seed2 (cdr lst))))))
(define (fold-packages proc init)
"Call (PROC PACKAGE RESULT) for each available package, using INIT as
the initial value of RESULT."
(fold (lambda (module result)
(fold (lambda (var result)
(if (package? var)
(proc var result)
result))
result
(module-map (lambda (sym var)
(false-if-exception (variable-ref var)))
module)))
init
(package-modules)))
the initial value of RESULT. It is guaranteed to never traverse the
same package twice."
(identity ; discard second return value
(fold2 (lambda (module result seen)
(fold2 (lambda (var result seen)
(if (and (package? var)
(not (vhash-assq var seen)))
(values (proc var result)
(vhash-consq var #t seen))
(values result seen)))
result
seen
(module-map (lambda (sym var)
(false-if-exception (variable-ref var)))
module)))
init
vlist-null
(package-modules))))
(define* (find-packages-by-name name #:optional version)
"Return the list of packages with the given NAME. If VERSION is not #f,