From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ricardo Wurmus <rekado@elephly.net>
Subject: Re: [go-build-system] How to access properties or keys of a package
	on the build side?
Date: Mon, 28 Aug 2017 22:32:41 +0200
Message-ID: <87bmmzh1qu.fsf@elephly.net>
References: <20170828185144.GA24652@jasmine.lan> <87d17fh5b6.fsf@elephly.net>
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To: Leo Famulari <leo@famulari.name>
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Ricardo Wurmus <rekado@elephly.net> writes:

> You could also access the arguments of another package with
> “package-arguments”.  Using the “properties” field isn’t pretty because
> it is a free form alist.
>
> You can use “find-tail” to jump to the keyword in “arguments” and then
> pick the following value.

Here an example:

--8<---------------cut here---------------start------------->8---
(define (assoc-args-ref pkg key)
  "Return the value associated with KEY in the arguments of package PKG,
or #F if there is no such key."
  (let ((ref (find-tail (cut eq? <> key)
                        (package-arguments pkg))))
    (and=> ref second)))

(assoc-args-ref golang-github-com-audriusbutkevicius-go-nat-pmp
                #:import-path)

=> "github.com/AudriusButkevicius/go-nat-pmp"
--8<---------------cut here---------------end--------------->8---


-- 
Ricardo

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