Effectively Splicing a List of Arguments into a Function Call

Question

Some of the Common Lisp list and sequence functions can take multiple lists or sequences as their final arguments. For example:

(mapcar #'list '(a b) '(c d) '(e f)) => ((a c e) (b d f))

But if the final arguments are already consolidated into a list/sequence like ((a b) (c d) (e f) ...), how can you achieve the same result (as if the list/sequence were spliced into the original function)? Is there a more straightforward approach than writing a macro?

EDIT: I think I've found one way: (apply #'funcall #'mapcar #'list '((a b) (c d) (e f))) but there may be others.

That `#'funcall` is unnecessary. – jkiiski Aug 31 '19 at 18:05 — jkiiski, Aug 31 '19 at 18:05

score 3 · Accepted Answer · answered Aug 31 '19 at 19:07

3

You use apply, which takes as last argument a spreadable arguments list designator.

For your example:

(apply #'mapcar #'list '((a b) (c d) (e f)))

answered Aug 31 '19 at 19:07

Svante

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[This answer](https://stackoverflow.com/a/33553757/1281433) (disclaimer, I wrote it) has some more examples of spreadable arglists. – Joshua Taylor Sep 02 '19 at 20:01

Effectively Splicing a List of Arguments into a Function Call

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