Hi Julien!

> Well, look at the location of that "src". You have ("src" (string-append 
> …)). That can't work, "src" is a string, not a function (that's what the 
> error message is trying to tell you).
> 
> Since you need two lists for the install-plan, you can fix that with:
> 
> #:install-plan
> (list (list "src" (string-append …)))

Wouldn't that make `"src"` and `(string-append "include/" solutions)` 
make two separate components of a list? They must be one single argument.

Regards,
RG.