Re: [Chicken-users] How to use prelude?

[felix winkelmann]

On 5/27/06, Peter Bex <address@hidden> wrote:
> Hey all,
>
> I'm trying to conditionally add a prelude to an egg.  It checks if X is
> available by trying to link against it, and then it does the following:
>
> (if with-x?
>     (compile -prelude (define with-x #t) -s -O2 -d0 imlib2.scm -C 
> -I/usr/X11R6/include -L/usr/X11R6/lib -lImlib2 -lX11 -lfreetype)
>     (compile -prelude (define with-x #t) -s -O2 -d0 imlib2.scm -ffi-define 
> X_DISPLAY_MISSING))
>
> But this fails on the prelude with:
> Syntax error: "(" unexpected
>
> Adding a quote in front of the define doesn't work either as that expands
> to (quote (define with-x #t))

Try "'...'" (one pair of double-quotes for scheme, and one pair of single
quotes for the shell).

> How does this work, then?  (also, can I use cond-expand with this?  I'm not
> sure how to add features cond-expand can check against)

As Kon replied: register-feature! is the way. But that is at run-time,
of course.
To have it available at compile-time (I'm not 100% sure in what way you
want to use this), things are (as usual) a tiny little bit more complicated.


cheers,
felix