qrazhan/perl5i — comment on commit 99e6b80ce70698c85478e826e6d420bcc4b6414c
File: t/pick.t line 58
By exodist:

However, it is important to note that '=>' will quote a value on the left in many cases:

1 => 2 # will quote 1 so that it is "1" (not a big deal in perl)
foo => 'bar' #will quote 'foo' for you, which may not be what you want if foo is actually a function call (easily fixed by adding parens)

In most cases, specially [...] => ... the => will act just like a comma, but the quoting can bite you if you use a keyword or function, or special thing on the left. But I agree with schwern that the visual difference is well worth it.