What does `&:` mean in this Ruby snippet?

Question

This is from a solution I saw at a competitive programming site:

    gets.split.map &:to_i

The &:to_i phrase seems to be equivalent to {|s| s.to_i}, but I can't find anything about that syntax at ruby-doc.org, or a match for "&:" [ruby] here. (I don't know what to call it for an English language search, either.)

If it matters, that site is using Ruby 3.0.1.

Symbolhound is great for this sort of thing: http://symbolhound.com/?q=ruby+%26%3A — mu is too short, Mar 05 '22 at 17:52

score 0 · Accepted Answer · edited Mar 06 '22 at 02:36

0

It's an example of Symbol#to_proc - see https://www.brianstorti.com/understanding-ruby-idiom-map-with-symbol/ for a more detailed explanation, or the ruby API documentation

edited Mar 06 '22 at 02:36

engineersmnky

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answered Mar 05 '22 at 16:24

eugen

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Thank you! The API doc link is what I tried to find, but I still don't see how I'd have found it on my own if I didn't already know the answer to my question. – Mike Housky Mar 23 '22 at 10:12

What does `&:` mean in this Ruby snippet?

1 Answers1