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-rw-r--r--gnu/services/configuration.scm29
1 files changed, 21 insertions, 8 deletions
diff --git a/gnu/services/configuration.scm b/gnu/services/configuration.scm
index 2ad3a637a4..0a2219e743 100644
--- a/gnu/services/configuration.scm
+++ b/gnu/services/configuration.scm
@@ -1,5 +1,6 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 Andy Wingo <wingo@igalia.com>
+;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -36,6 +37,7 @@
configuration-field-default-value-thunk
configuration-field-documentation
serialize-configuration
+ define-maybe
define-configuration
validate-configuration
generate-documentation
@@ -85,16 +87,27 @@
(configuration-field-name field) val))))
fields))
+(define-syntax-rule (id ctx parts ...)
+ "Assemble PARTS into a raw (unhygienic) identifier."
+ (datum->syntax ctx (symbol-append (syntax->datum parts) ...)))
+
+(define-syntax define-maybe
+ (lambda (x)
+ (syntax-case x ()
+ ((_ stem)
+ (with-syntax
+ ((stem? (id #'stem #'stem #'?))
+ (maybe-stem? (id #'stem #'maybe- #'stem #'?))
+ (serialize-stem (id #'stem #'serialize- #'stem))
+ (serialize-maybe-stem (id #'stem #'serialize-maybe- #'stem)))
+ #'(begin
+ (define (maybe-stem? val)
+ (or (eq? val 'disabled) (stem? val)))
+ (define (serialize-maybe-stem field-name val)
+ (when (stem? val) (serialize-stem field-name val)))))))))
+
(define-syntax define-configuration
(lambda (stx)
- (define (id ctx part . parts)
- (let ((part (syntax->datum part)))
- (datum->syntax
- ctx
- (match parts
- (() part)
- (parts (symbol-append part
- (syntax->datum (apply id ctx parts))))))))
(syntax-case stx ()
((_ stem (field (field-type def) doc) ...)
(with-syntax (((field-getter ...)