January 1, 2015 by Daniel P. Clark

When to use Ampersand and/or Colon with Proc, Map, and Inject

So with Ruby permitting Procs called on Objects I’ve found sometimes a Colon Method will work, and sometimes you need a Ampersand Colon Method.  For example, when I map &:upcase on a list of strings it works.

But if I try without the Ampersand I get:

So for mapping it seems we need…

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