How to replace %output with #$output?

How to replace %output with #$output?

[Mekeor Melire]

In the IRC-channel, I was told that the undocumented, magic %output
variable is deprecated. Instead, I should use #$output. But I couldn't
get this done. I always ran into strange errors.

How should I change the following snippet?

--8<---------------cut here---------------start------------->8---
    (arguments
      '(
         #:tests? #f ; no tests
         #:make-flags (list "CC=gcc")
         #:phases
         (modify-phases %standard-phases
             (delete 'configure)
             (add-after 'unpack 'patch-makefile
               (lambda _
                 (substitute* "Makefile"
                   (("/usr/local") %output)))))))
--8<---------------cut here---------------end--------------->8---

The whole file is available here: http://ix.io/3T71/scm

Re: How to replace %output with #$output?

[Tobias Geerinckx-Rice]

Hi Mekeor,

Remove the quote after arguments (replace it with a plain LIST call) and add #~ before (modify-phases ...) to define a gexp.

Untested example:

    (arguments
      (list #:tests? #f ; no tests
             #:make-flags (list "CC=gcc")
             #:phases
             #~(modify-phases %standard-phases
                 (delete 'configure)
                 (add-after 'unpack 'patch-makefile
                   (lambda _
                     (substitute* "Makefile"
                       (("/usr/local")
                        #$output)))))))

Also, newlines after ( make the baby Jesus cry.

So does hard-coding 'gcc' over using (cc-for-target).

Very strong opinions on Scheme coding style, that boy.

Kind regards,

T G-R

Sent on the go.  Excuse or enjoy my brevity.

Re: How to replace %output with #$output?

[Mekeor Melire]

2022-03-21 / 21:57 / me@tobias.gr:

> Remove the quote after arguments (replace it with a plain LIST call) and add #~ before (modify-phases ...) to define a gexp.
>
> Untested example:
>
>     (arguments
>       (list #:tests? #f ; no tests
>              #:make-flags (list "CC=gcc")
>              #:phases
>              #~(modify-phases %standard-phases
>                  (delete 'configure)
>                  (add-after 'unpack 'patch-makefile
>                    (lambda _
>                      (substitute* "Makefile"
>                        (("/usr/local")
>                         #$output)))))))

With these changes I get this error:

	Wrong type to apply: "CC=gcc"

> So does hard-coding 'gcc' over using (cc-for-target).

Yes, I would also prefer to use cc-for-target. But I wanted to simplify
my code first. Because in order to use cc-for-target, I have to use
backticks. If you have a suggestion for how to use both cc-for-target
and #$output, let me know.

> Very strong opinions on Scheme coding style, that boy.

Please don't assume gender. But yes, you can refer to me with the "he"
pronoun.

Re: How to replace %output with #$output?

[Tobias Geerinckx-Rice]

On 22 March 2022 07:26:38 UTC, Mekeor Melire <mekeor@posteo.de> wrote:
> (list "CC=gcc")
>
>With these changes I get this error:
>
>	Wrong type to apply: "CC=gcc"

That can happen only if you apply the string as a procedure, i.e. forgot the the LIST.

>> So does hard-coding 'gcc' over using (cc-for-target).
>
>Yes, I would also prefer to use cc-for-target. But I wanted to simplify
>my code first. Because in order to use cc-for-target, I have to use
>backticks.

Why?  Backticks are just short for UNQUOTE.  I don't see why you'd need or even want to use that here.  If you insist, you could write:

  `(,(string-append "CC=" (cc-for-target)))

but I'd much prefer you didn't as I think it's a step back from

(list (string-append "CC=" (cc-for-target)))

>> Very strong opinions on Scheme coding style, that boy.
>
>Please don't assume gender. But yes, you can refer to me with the "he"
>pronoun.

If you believe yourself to be the son of god, you have problems I can't help you fix. ;-) 
Hi Mekeor,

Kind regards,

T G-R

Sent on the go.  Excuse or enjoy my brevity.

Re: How to replace %output with #$output?

[Feng Shu]

Mekeor Melire <mekeor@posteo.de> writes:

> 2022-03-21 / 21:57 / me@tobias.gr:
>
>> Remove the quote after arguments (replace it with a plain LIST call) and add #~ before (modify-phases ...) to define a gexp.
>>
>> Untested example:
>>
>>     (arguments
>>       (list #:tests? #f ; no tests
>>              #:make-flags (list "CC=gcc")
>>              #:phases
>>              #~(modify-phases %standard-phases
>>                  (delete 'configure)
>>                  (add-after 'unpack 'patch-makefile
>>                    (lambda _
>>                      (substitute* "Makefile"
>>                        (("/usr/local")
>>                         #$output)))))))
>
> With these changes I get this error:
>
> 	Wrong type to apply: "CC=gcc"

What about #~(list "CC=gcc") or '(list "CC=gcc") ?


>
>> So does hard-coding 'gcc' over using (cc-for-target).
>
> Yes, I would also prefer to use cc-for-target. But I wanted to simplify
> my code first. Because in order to use cc-for-target, I have to use
> backticks. If you have a suggestion for how to use both cc-for-target
> and #$output, let me know.
>
>> Very strong opinions on Scheme coding style, that boy.
>
> Please don't assume gender. But yes, you can refer to me with the "he"
> pronoun.

-- 

Re: How to replace %output with #$output?

[Mekeor Melire]

2022-03-22 / 07:59 / me@tobias.gr:

> On 22 March 2022 07:26:38 UTC, Mekeor Melire <mekeor@posteo.de> wrote:

>> (list "CC=gcc")
>>
>>With these changes I get this error:
>>
>>	Wrong type to apply: "CC=gcc"
>
> That can happen only if you apply the string as a procedure, i.e.
> forgot the the LIST.

The `list` was present. As suggested by Feng Shu in another thread, it
works like this:

--8<---------------cut here---------------start------------->8---
    (arguments
      (list
         #:tests? #f ; no tests
         #:make-flags #~(list "CC=gcc")
         #:phases
         #~(modify-phases %standard-phases
             (delete 'configure)
             (add-after 'unpack 'patch-makefile
               (lambda _
                 (substitute* "Makefile"
                   (("/usr/local") #$output)))))))
--8<---------------cut here---------------end--------------->8---

It also seems to work with:

    #:make-flags '(list "CC=gcc")



>>> So does hard-coding 'gcc' over using (cc-for-target).
>>
>>Yes, I would also prefer to use cc-for-target. But I wanted to simplify
>>my code first. Because in order to use cc-for-target, I have to use
>>backticks.
>
> Why? Backticks are just short for UNQUOTE. I don't see why you'd need
> or even want to use that here. If you insist, you could write:
>
>   `(,(string-append "CC=" (cc-for-target)))
>
> but I'd much prefer you didn't as I think it's a step back from
>
> (list (string-append "CC=" (cc-for-target)))

Do I have to import cc-for-target from (guix utils)?

In case of:

    ;; do not have (guix utils) imported
    #:make-flags (list (string-append "CC=" (cc-for-target)))

I get this during build:

    error: cc-for-target: unbound variable

In case of:

    ;; have (guix utils) imported
    #:make-flags (list (string-append "CC=" (cc-for-target)))

I get this error:

    Wrong type to apply: "CC=gcc"

In case of:

    ;; have (guix utils) imported
    #:make-flags #~(list (string-append "CC=" (cc-for-target)))

I get this error:

    Unbound variable: cc-for-target

In case of:

    ;; have (guix utils) imported
    #:make-flags `(list (string-append "CC=" ,(cc-for-target)))

I get this error ... Oh, wait, it works!

So this is the working code:

--8<---------------cut here---------------start------------->8---
    (arguments
      (list
         #:tests? #f ; no tests
         #:make-flags `(list (string-append "CC=" ,(cc-for-target)))
         #:phases
         #~(modify-phases %standard-phases
             (delete 'configure)
             (add-after 'unpack 'patch-makefile
               (lambda _
                 (substitute* "Makefile"
                   (("/usr/local") #$output)))))))
--8<---------------cut here---------------end--------------->8---

Putting the comma like this also seems to work:

    #:make-flags `(list (string-append "CC=" ,(cc-for-target)))

>>> Very strong opinions on Scheme coding style, that boy.
>>
>>Please don't assume gender. But yes, you can refer to me with the "he"
>>pronoun.
>
> If you believe yourself to be the son of god, you have problems I
> can't help you fix. ;-)

I see. Sorry for misunderstanding :-)

Re: How to replace %output with #$output?

[Mekeor Melire]

2022-03-22 / 16:16 / tumashu@163.com:

> Mekeor Melire <mekeor@posteo.de> writes:
>
>> 2022-03-21 / 21:57 / me@tobias.gr:
>>
>>> Remove the quote after arguments (replace it with a plain LIST call) and add #~ before (modify-phases ...) to define a gexp.
>>>
>>> Untested example:
>>>
>>>     (arguments
>>>       (list #:tests? #f ; no tests
>>>              #:make-flags (list "CC=gcc")
>>>              #:phases
>>>              #~(modify-phases %standard-phases
>>>                  (delete 'configure)
>>>                  (add-after 'unpack 'patch-makefile
>>>                    (lambda _
>>>                      (substitute* "Makefile"
>>>                        (("/usr/local")
>>>                         #$output)))))))
>>
>> With these changes I get this error:
>>
>> 	Wrong type to apply: "CC=gcc"
>
> What about #~(list "CC=gcc") or '(list "CC=gcc") ?

It works. Thank you :)

Re: How to replace %output with #$output?

[Tobias Geerinckx-Rice]

Mekeor,

> #~(list "CC=gcc")

Yes of course it works like this wh—

Oh.  D'oh.  My bad!  Glad to hear you got there in the end.

Kind regards,

T G-R

Sent on the go.  Excuse or enjoy my brevity.