Wonderful! But slightly off the specs. Well, perhaps. ;-) 

#!perl -l
#

sub hmap (&%) {
    my $code = shift;
    local $_;
    my @rv;
    push @rv, shift, $code->($_=shift) while @_;
    @rv;
}
sub hgrep (&%) {
    my $code = shift;
    local $_;
    my @rv;
    push (@rv, ($code->($_=$_[1]) ? (shift,$_):())),shift while @_;
    @rv;
}   

%h = (foo => 1, bar => 2, baz => 3);

%new =  hmap { ++$_ } %h;
print "hmap result:";
print "$_ => $new{$_}" for keys %new;

%new = hgrep { /2/ } %h;
print "hgrep result:";
print "found $_ => $new{$_}" for keys %new;
__END__
hmap result:
bar => 3
baz => 4
foo => 2
hgrep result:
bar => 2

[download]

update: well, this operates on the value only, localizing $_ and doesn't create package vars. For the key... hm. What do we have? $", $/, $\ ... - no, they could be used inside the block. But then... we could localize @_ here! 

sub hmap (&%) {
    my $code = shift;
    my @i = @_;
    local @_;
    my @rv;
    push @rv, $code->(@_=(shift @i,shift @i)) while @i;
    @rv;
}
%h = (foo => 1, bar => 2, baz => 3);

%new =  hmap { $_[0]."l",++$_[1] } %h;
print "hmap result:";
print "$_ => $new{$_}" for keys %new;
__END__
hmap result:
bazl => 4
barl => 3
fool => 2

[download]

update 2: BrowserUk, as you may have noticed, I ommitted the 'hgrep' part here, since my solution doesn't work - seem to not dunno how to change its arguments inside the block... ;-)

In reply to Re^2: map and grep (but for hashes) by shmem
in thread map and grep (but for hashes) by zerohero

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