> hi,
>
> why do the configure-flags and make-flags need to be doubly quote in the
> gnu-build procedure?
Because later in that function they get unquoted inside a gexp using
`#$` (i.e. `ungexp`).
If you write a gexp like
> (let ((somelist '("a" "b" "c")))
> #~(display #$somelist))
on the build side it will resolve to
> (display ("a" "b" "c"))
which will of course fail because `"a"` is not a proper function. You
instead want to get this
> (display '("a" "b" "c"))
which can be achieved by e.g. double-quoting the value that gets
ungexp'd, e.g. with
> (let ((somelist ''("a" "b" "c")))
> #~(display #$somelist))
The following should also work for this list
> (let ((somelist '("a" "b" "c")))
> #~(display '#$somelist))
In many places in Guix code a function `sexp->gexp` is also used
together with `'#$`. I suspect it does some extra stuff. I don't know
what exactly.
The relevant part where those double-quoted lists are used is
>#:locale #$locale
>#:bootstrap-scripts #$bootstrap-scripts
>#:configure-flags #$(if (pair? configure-flags)
>(sexp->gexp
> configure-flags) ; here
>configure-flags)
>#:make-flags #$(if (pair? make-flags)
> (sexp->gexp make-flags)
> ; here
> make-flags)
>#:out-of-source? #$out-of-source?
>#:tests? #$tests?
>#:test-target #$test-target
When a double-quoted list is used, the "true" expression of each `if`
clause is used :)
Wojtek
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On Wed, 7 Dec 2022 00:14:51 -0600
jgart wrote:
> hi,
>
> why do the configure-flags and make-flags need to be doubly quote in the
> gnu-build procedure?
>
> (define* (gnu-build name inputs
> #:key
> guile source
> (outputs '("out"))
> (search-paths '())
> (bootstrap-scripts %bootstrap-scripts)
> (configure-flags ''()) ; here
> (make-flags ''()) ; here
> (out-of-source? #f)
> (tests? #t)
> (test-target "check")
> (parallel-build? #t)
> (parallel-tests? #t)
> (patch-shebangs? #t)
> (strip-binaries? #t)
> (strip-flags %strip-flags)
> (strip-directories %strip-directories)
> (validate-runpath? #t)
> (make-dynamic-linker-cache? #t)
> (license-file-regexp %license-file-regexp)
> (phases '%standard-phases)
> (locale "en_US.utf8")
> (system (%current-system))
> (build (nix-system->gnu-triplet system))
> (imported-modules %gnu-build-system-modules)
> (modules %default-modules)
> (substitutable? #t)
> allowed-references
> disallowed-references)
>
>
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