Hash of Regex

[bichonfrise74]

I'm trying to build a hash of possible substitutes for a given word or regex. So, I came up with this.

#!/usr/bin/perl

use strict;

my $test = 'The brown fox int(10) over float(200) fence.';

my %dict = ( 'brown'      => 'yellow',
             /int(\d+)/   => 'int',
             /float(\d+)/ => 'float',
           );

for my $i (keys %dict) {
    $test =~ s/($i)/$dict{$i}/gi;
}

print "$test\n";

This is the output.

The yellow fox float(10) over float(200) fence.

My expected output is something like this.

The yellow fox int over float fence.

So, I'm not sure if I can put regex in the keys of my hash and use that to check for possible substitutes. Also, why did int(10) become float(10) in the output??