Re: how to substiute given key with value by using hash.

[happy.barney]

my %hash = (...);
my $src = do { local $/; <> };
my $res = join '', map $hash{$_} // $_, split /\b/, $src;

# %hash = (a => 'xxx')
# $src = 'a b ab';
# $res = 'xxx b ab';