> > 2. I'd like to use
> >
> > (patch-shebang (string-append bin "/grue-hunter")
> > 			   (list perl))

> Should be (list (string-append perl "/bin")).

I don't think so.  Here's the output of (display (string-append "PERL: " perl "\n")):

PERL: /nix/store/rp1fdpa8fa4cdx3j76yyhi45lgx796nw-perl-5.16.1/bin/perl

And 'perl' is defined like this:

(perl (string-append (assoc-ref %build-inputs
                                "perl")
                     "/bin/perl"))

There is also a corresponding line in 'inputs'.  Why does the mentioned
'patch-shebang' line return the following?

patch-shebang: /nix/store/k6w3d29k2i9acj3v9ypy19v4sqxki8gk-grue-hunter-1.0/bin/grue-hunter: warning: no binary for interpreter `perl' found in $PATH

Note that 'substitute*' works fine.