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Re: Problem with append


> It seems that append in guile has a problem
> 
> I expect:
> 
> (append '(1 2) () '(3 4)) --> (1 2 3 4)

Yes, that's what I get:

    zwingli:jimb$ /calvin/jimb/guile/sun4u/bin/guile
    guile> (append '(1 2) () '(3 4))
    (1 2 3 4)
    guile> 

Is this not what you see?

Actually, this should raise an error, since () is not a valid
expression in R4RS or R5RS.  But Guile treates it as equivalent to
'(), I think as a vestige of a time when we were trying to finagle the
interpretation of the Report to get a language as close to Emacs Lisp
as possible.  (Not the approach we want to take nowadays.)