What is the lisp equivalent of javascript's spread operator?

Question

Say I wanted to find the highest square of a bunch of numbers:

(max (map (lambda (x) (* x x)) (range -4 1))) ; I want 16

This doesn't work: max expects to be called like (max 16 9 4 1 0) and I'm calling it like (max '(16 9 4 1 0)).

The operation I want to apply here is the same as Python's asterisk or Javascript's spread operator, but it's neither quoting, unquoting or quasi-quoting...

What is it called in lisp (or Scheme) (or Racket) and how do I perform it? This seems like such a basic operation I'm struggling to find appropriate search terms on Google.

So far the best I've got is a really sad

(argmax (lambda (x) x) (map (lambda (x) (* x x)) (range -4 1))) ; 16 but really sadly so

Possible duplicate of [Unroll / splat arguments in common lisp](https://stackoverflow.com/questions/2345999/unroll-splat-arguments-in-common-lisp) and [Can Scheme expand a list as arguments?](https://stackoverflow.com/questions/17035725/can-scheme-expand-a-list-as-arguments) — amalloy, Dec 10 '19 at 19:47

score 2 · Answer 1 · edited Dec 10 '19 at 19:22

2

Use apply to spread a list into arguments.

(apply max (map (lambda (x) (* x x)) (range -4 1)))

edited Dec 10 '19 at 19:22

badp

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answered Dec 10 '19 at 19:20

Barmar

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score 2 · Accepted Answer · answered Dec 10 '19 at 19:58

JavaScript rest syntax was included in ECMA2015 / ES6 and before 2015 you had this syntax:

Math.max.apply(
  null,
  [-4, -3, -2, 1].map(function (v) {return v*v; }),
);
// ==> 16

And Scheme had it already in the 70s:

(apply max 
       (map (lambda (v) 
              (* v v)) 
       '(-4 -3 -2 1)))
; ==> 16

Note that JS apply is less powerful than that of Scheme / Common Lisp. Eg. you could add extra arguments which JS does not support:

(apply map list '((1 2 3) (a b c)))
; ==> ((1 a) (2 b) (3 c))

What is the lisp equivalent of javascript's spread operator?

2 Answers2