you can shave off two characters by omitting the parentheses.

If you want to omit characters, you can write

my %hash = map $_=>1, qw(shave the modern way);
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Update: I'm sorry, I should have tested this code... thanks to lodin, see below.

(Not to mention the whitespace... but often some more characters make the code more readable.)

I find it quite natural that map uses list context and grep uses scalar context. grep's block evaluates to a boolean value (whether or not to include the element), which is a scalar. map's block evaluates to... well, a list. If this were not the case, the parentheses would not help.

One remark about this "map" solution: Note that this works only once. If you use the hash-slice solution, you can add something to the set several times.