=> is almost the same as ,

The difference is that => forces the value to the left of it to be interpreted as a quoted string

This is why

#!/usr/bin/perl -w

my %a=( foo => "bar",
        fi , "fo");
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Will get you a warning for the unquoted fi, but not the unquoted foo. However, normal operator precedence still applies, so

print join , => @to_print;
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won't work, whereas

print join or => @to_print;
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will.