From Newsgroup: comp.lang.scheme

Frode Vatvedt Fjeld wrote:

(sum '(2 3 4)) => 9
(sum '(5 6)) => 11

The usual way of doing this would be

(reduce #'+ '(2 3 4))

which is considered to be preferable to using APPLY. LOOP can do the
job almost as well:

(loop for x in '(2 3 4) sum x)

The thing about LOOP is that it's much more flexible, in case you need
some slight variation of the theme, like for example:

(loop for x in '(2 3 a 4) when (numberp x) sum x)

Gauche Scheme

(use gauche.lazy) ;; lfilter [lazy filtering]

(fold + 0 (lfilter number? '(2 3 a 4)))
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