482 lines
19 KiB
Scheme
482 lines
19 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2015 Andy Wingo <wingo@igalia.com>
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;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
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;;; Copyright © 2017, 2018 Clément Lassieur <clement@lassieur.org>
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;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
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;;; Copyright © 2021, 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
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;;; Copyright © 2021 Andrew Tropin <andrew@trop.in>
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;;; Copyright © 2022 Maxime Devos <maximedevos@telenet.be>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu services configuration)
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#:use-module (guix packages)
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#:use-module (guix records)
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#:use-module (guix gexp)
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#:use-module ((guix utils) #:select (source-properties->location))
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#:use-module ((guix diagnostics)
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#:select (formatted-message location-file &error-location))
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#:use-module ((guix modules) #:select (file-name->module-name))
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#:use-module (guix i18n)
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#:autoload (texinfo) (texi-fragment->stexi)
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#:autoload (texinfo serialize) (stexi->texi)
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#:use-module (ice-9 curried-definitions)
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#:use-module (ice-9 format)
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#:use-module (ice-9 match)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-34)
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#:use-module (srfi srfi-35)
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#:export (configuration-field
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configuration-field-name
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configuration-field-type
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configuration-missing-field
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configuration-field-error
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configuration-field-serializer
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configuration-field-getter
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configuration-field-default-value-thunk
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configuration-field-documentation
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configuration-error?
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define-configuration
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define-configuration/no-serialization
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no-serialization
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serialize-configuration
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define-maybe
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define-maybe/no-serialization
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%unset-value
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maybe-value
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maybe-value-set?
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generate-documentation
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configuration->documentation
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empty-serializer
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serialize-package
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filter-configuration-fields
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interpose
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list-of
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list-of-strings?
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alist?
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serialize-file-like
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text-config?
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serialize-text-config
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generic-serialize-alist-entry
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generic-serialize-alist))
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;;; Commentary:
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;;;
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;;; Syntax for creating Scheme bindings to complex configuration files.
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;;;
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;;; Code:
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(define-condition-type &configuration-error &error
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configuration-error?)
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(define (configuration-error message)
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(raise (condition (&message (message message))
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(&configuration-error))))
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(define (configuration-field-error loc field value)
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(raise (apply
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make-compound-condition
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(formatted-message (G_ "invalid value ~s for field '~a'")
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value field)
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(condition (&configuration-error))
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(if loc
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(list (condition
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(&error-location (location loc))))
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'()))))
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(define (configuration-missing-field kind field)
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(configuration-error
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(format #f "~a configuration missing required field ~a" kind field)))
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(define (configuration-missing-default-value kind field)
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(configuration-error
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(format #f "The field `~a' of the `~a' configuration record \
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does not have a default value" field kind)))
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(define-record-type* <configuration-field>
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configuration-field make-configuration-field configuration-field?
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(name configuration-field-name)
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(type configuration-field-type)
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(getter configuration-field-getter)
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(predicate configuration-field-predicate)
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(serializer configuration-field-serializer)
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(default-value-thunk configuration-field-default-value-thunk)
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(documentation configuration-field-documentation))
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(define (serialize-configuration config fields)
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#~(string-append
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#$@(map (lambda (field)
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((configuration-field-serializer field)
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(configuration-field-name field)
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((configuration-field-getter field) config)))
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fields)))
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(define-syntax-rule (id ctx parts ...)
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"Assemble PARTS into a raw (unhygienic) identifier."
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(datum->syntax ctx (symbol-append (syntax->datum parts) ...)))
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(define (define-maybe-helper serialize? prefix syn)
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(syntax-case syn ()
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((_ stem)
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(with-syntax
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((stem? (id #'stem #'stem #'?))
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(maybe-stem? (id #'stem #'maybe- #'stem #'?))
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(serialize-stem (if prefix
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(id #'stem prefix #'serialize- #'stem)
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(id #'stem #'serialize- #'stem)))
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(serialize-maybe-stem (if prefix
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(id #'stem prefix #'serialize-maybe- #'stem)
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(id #'stem #'serialize-maybe- #'stem))))
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#`(begin
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(define (maybe-stem? val)
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(or (not (maybe-value-set? val))
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(stem? val)))
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#,@(if serialize?
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(list #'(define (serialize-maybe-stem field-name val)
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(if (stem? val)
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(serialize-stem field-name val)
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"")))
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'()))))))
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(define-syntax define-maybe
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(lambda (x)
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(syntax-case x (no-serialization prefix)
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((_ stem (no-serialization))
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(define-maybe-helper #f #f #'(_ stem)))
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((_ stem (prefix serializer-prefix))
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(define-maybe-helper #t #'serializer-prefix #'(_ stem)))
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((_ stem)
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(define-maybe-helper #t #f #'(_ stem))))))
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(define-syntax-rule (define-maybe/no-serialization stem)
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(define-maybe stem (no-serialization)))
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(define (normalize-field-type+def s)
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(syntax-case s ()
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((field-type def)
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(identifier? #'field-type)
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(values #'(field-type def)))
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((field-type)
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(identifier? #'field-type)
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(values #'(field-type %unset-value)))
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(field-type
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(identifier? #'field-type)
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(values #'(field-type %unset-value)))))
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(define (define-configuration-helper serialize? serializer-prefix syn)
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(syntax-case syn ()
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((_ stem (field field-type+def doc custom-serializer ...) ...)
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(with-syntax
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((((field-type def) ...)
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(map normalize-field-type+def #'(field-type+def ...))))
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(with-syntax
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(((field-getter ...)
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(map (lambda (field)
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(id #'stem #'stem #'- field))
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#'(field ...)))
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((field-predicate ...)
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(map (lambda (type)
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(id #'stem type #'?))
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#'(field-type ...)))
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((field-default ...)
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(map (match-lambda
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((field-type default-value)
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default-value))
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#'((field-type def) ...)))
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((field-serializer ...)
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(map (lambda (type custom-serializer)
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(and serialize?
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(match custom-serializer
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((serializer)
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serializer)
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(()
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(if serializer-prefix
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(id #'stem
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serializer-prefix
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#'serialize- type)
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(id #'stem #'serialize- type))))))
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#'(field-type ...)
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#'((custom-serializer ...) ...))))
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(define (field-sanitizer name pred)
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;; Define a macro for use as a record field sanitizer, where NAME
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;; is the name of the field and PRED is the predicate that tells
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;; whether a value is valid for this field.
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#`(define-syntax #,(id #'stem #'validate- #'stem #'- name)
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(lambda (s)
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;; Make sure the given VALUE, for field NAME, passes PRED.
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(syntax-case s ()
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((_ value)
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(with-syntax ((name #'#,name)
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(pred #'#,pred)
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(loc (datum->syntax #'value
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(syntax-source #'value))))
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#'(if (pred value)
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value
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(configuration-field-error
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(and=> 'loc source-properties->location)
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'name value))))))))
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#`(begin
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;; Define field validation macros.
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#,@(map field-sanitizer
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#'(field ...)
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#'(field-predicate ...))
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(define-record-type* #,(id #'stem #'< #'stem #'>)
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stem
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#,(id #'stem #'make- #'stem)
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#,(id #'stem #'stem #'?)
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#,@(map (lambda (name getter def)
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#`(#,name #,getter (default #,def)
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(sanitize
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#,(id #'stem #'validate- #'stem #'- name))))
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#'(field ...)
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#'(field-getter ...)
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#'(field-default ...))
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(%location #,(id #'stem #'stem #'-source-location)
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(default (and=> (current-source-location)
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source-properties->location))
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(innate)))
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(define #,(id #'stem #'stem #'-fields)
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(list (configuration-field
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(name 'field)
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(type 'field-type)
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(getter field-getter)
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(predicate field-predicate)
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(serializer field-serializer)
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(default-value-thunk
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(lambda ()
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(display '#,(id #'stem #'% #'stem))
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(if (maybe-value-set? (syntax->datum field-default))
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field-default
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(configuration-missing-default-value
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'#,(id #'stem #'% #'stem) 'field))))
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(documentation doc))
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...))))))))
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(define no-serialization ;syntactic keyword for 'define-configuration'
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'(no serialization))
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(define-syntax define-configuration
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(lambda (s)
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(syntax-case s (no-serialization prefix)
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((_ stem (field field-type+def doc custom-serializer ...) ...
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(no-serialization))
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(define-configuration-helper
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#f #f #'(_ stem (field field-type+def doc custom-serializer ...)
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...)))
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((_ stem (field field-type+def doc custom-serializer ...) ...
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(prefix serializer-prefix))
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(define-configuration-helper
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#t #'serializer-prefix #'(_ stem (field field-type+def
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doc custom-serializer ...)
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...)))
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((_ stem (field field-type+def doc custom-serializer ...) ...)
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(define-configuration-helper
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#t #f #'(_ stem (field field-type+def doc custom-serializer ...)
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...))))))
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(define-syntax-rule (define-configuration/no-serialization
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stem (field field-type+def
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doc custom-serializer ...) ...)
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(define-configuration stem (field field-type+def
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doc custom-serializer ...) ...
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(no-serialization)))
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(define (empty-serializer field-name val) "")
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(define serialize-package empty-serializer)
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;; Ideally this should be an implementation detail, but we export it
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;; to provide a simpler API that enables unsetting a configuration
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;; field that has a maybe type, but also a default value. We give it
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;; a value that sticks out to the reader when something goes wrong.
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;;
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;; An example use-case would be something like a network application
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;; that uses a default port, but the field can explicitly be unset to
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;; request a random port at startup.
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(define %unset-value '%unset-marker%)
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(define (maybe-value-set? value)
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"Predicate to check whether a 'maybe' value was explicitly provided."
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(not (eq? %unset-value value)))
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;; Ideally there should be a compiler macro for this predicate, that expands
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;; to a conditional that only instantiates the default value when needed.
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(define* (maybe-value value #:optional (default #f))
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"Returns VALUE, unless it is the unset value, in which case it returns
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DEFAULT."
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(if (maybe-value-set? value)
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value
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default))
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;; A little helper to make it easier to document all those fields.
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(define (generate-documentation documentation documentation-name)
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(define (str x) (object->string x))
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(define (package->symbol package)
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"Return the first symbol name of a package that matches PACKAGE, else #f."
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(let* ((module (file-name->module-name
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(location-file (package-location package))))
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(symbols (filter-map
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identity
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(module-map (lambda (symbol var)
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(and (equal? package (variable-ref var))
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symbol))
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(resolve-module module)))))
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(if (null? symbols)
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#f
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(first symbols))))
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(define (generate configuration-name)
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(match (assq-ref documentation configuration-name)
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((fields . sub-documentation)
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`((deftp (% (category "Data Type") (name ,(str configuration-name)))
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(para "Available " (code ,(str configuration-name)) " fields are:")
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(table
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(% (formatter (asis)))
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,@(map
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(lambda (f)
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(let ((field-name (configuration-field-name f))
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(field-type (configuration-field-type f))
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(field-docs (cdr (texi-fragment->stexi
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(configuration-field-documentation f))))
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(default (catch #t
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(configuration-field-default-value-thunk f)
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(lambda _ '%invalid))))
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(define (show-default? val)
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(or (string? val) (number? val) (boolean? val)
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(package? val)
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(and (symbol? val) (not (eq? val '%invalid)))
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(and (list? val) (and-map show-default? val))))
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(define (show-default val)
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(cond
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((package? val)
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(symbol->string (package->symbol val)))
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(((list-of package?) val)
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(format #f "(~{~a~^ ~})" (map package->symbol val)))
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(else (str val))))
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`(entry (% (heading
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(code ,(str field-name))
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,@(if (show-default? default)
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`(" (default: "
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(code ,(show-default default)) ")")
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'())
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" (type: " ,(str field-type) ")"))
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(para ,@field-docs)
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,@(append-map
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generate
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(or (assq-ref sub-documentation field-name)
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'())))))
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fields)))))))
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(stexi->texi `(*fragment* . ,(generate documentation-name))))
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(define (configuration->documentation configuration-symbol)
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"Take CONFIGURATION-SYMBOL, the symbol corresponding to the name used when
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defining a configuration record with DEFINE-CONFIGURATION, and output the
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Texinfo documentation of its fields."
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;; This is helper for a simple, straight-forward application of
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;; GENERATE-DOCUMENTATION.
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(let ((fields-getter (module-ref (current-module)
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(symbol-append configuration-symbol
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'-fields))))
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(display (generate-documentation `((,configuration-symbol ,fields-getter))
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configuration-symbol))))
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(define* (filter-configuration-fields configuration-fields fields
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#:optional negate?)
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"Retrieve the fields listed in FIELDS from CONFIGURATION-FIELDS.
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If NEGATE? is @code{#t}, retrieve all fields except FIELDS."
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(filter (lambda (field)
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(let ((member? (member (configuration-field-name field) fields)))
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(if (not negate?) member? (not member?))))
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configuration-fields))
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(define* (interpose ls #:optional (delimiter "\n") (grammar 'infix))
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"Same as @code{string-join}, but without join and string, returns a
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DELIMITER interposed LS. Support 'infix and 'suffix GRAMMAR values."
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(when (not (member grammar '(infix suffix)))
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(raise
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(formatted-message
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(G_ "The GRAMMAR value must be 'infix or 'suffix, but ~a provided.")
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grammar)))
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(fold-right (lambda (e acc)
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(cons e
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(if (and (null? acc) (eq? grammar 'infix))
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acc
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(cons delimiter acc))))
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'() ls))
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(define (list-of pred?)
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"Return a procedure that takes a list and check if all the elements of
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the list result in @code{#t} when applying PRED? on them."
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(lambda (x)
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(if (list? x)
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(every pred? x)
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#f)))
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(define list-of-strings?
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(list-of string?))
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(define alist?
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(match-lambda
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(() #t)
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((head . tail) (and (pair? head) (alist? tail)))
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(_ #f)))
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(define serialize-file-like empty-serializer)
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(define (text-config? config)
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(list-of file-like?))
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(define (serialize-text-config field-name val)
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#~(string-append
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#$@(interpose
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(map
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(lambda (e)
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#~(begin
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(use-modules (ice-9 rdelim))
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(with-fluids ((%default-port-encoding "UTF-8"))
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(with-input-from-file #$e read-string))))
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val)
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"\n" 'suffix)))
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(define ((generic-serialize-alist-entry serialize-field) entry)
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"Apply the SERIALIZE-FIELD procedure on the field and value of ENTRY."
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(match entry
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((field . val) (serialize-field field val))))
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(define (generic-serialize-alist combine serialize-field fields)
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"Generate a configuration from an association list FIELDS.
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SERIALIZE-FIELD is a procedure that takes two arguments, it will be
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applied on the fields and values of FIELDS using the
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@code{generic-serialize-alist-entry} procedure.
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COMBINE is a procedure that takes one or more arguments and combines
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all the alist entries into one value, @code{string-append} or
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@code{append} are usually good candidates for this."
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(apply combine
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(map (generic-serialize-alist-entry serialize-field) fields)))
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