Mark H Weaver <mhw@netris.org> writes:

> David Thompson <dthompson2@worcester.edu> writes:
>
>> In GNU Make, the '?=' operator for variable assignment means "assign if
>> the variable isn't already defined"[1].  So, rather than a substitution,
>> how about just setting an environment variable?
>>
>>   (setenv "PREFIX" out)
>
> Another way is to add "PREFIX=..." to #:make-flags like this:
>
>   #:make-flags (list (string-append "PREFIX=" (assoc-ref %outputs "out")))
>
> See 'freedink-data' in gnu/packages/games.scm for an example of this.
>
>       Mark

I went with setenv since it's also done for "CC" and seems simpler.  Is
that OK?