How to interpolate CONSTANTS in Here docs?

CoVAX has asked for the wisdom of the Perl Monks concerning the following question:

I have some constants (defined with `use constant`) that I am desirous of using in a `here` doc. However no interpolation occurs, so the strings naming the constants literally appear instead of their values.

What I have resorted to is: assigning variables the values of the constants, and using the variable names in the here doc. Is there a better way to accomplish the desired behavior?

use constant {
OUT_DIR      => 'out',
OUT_FIELDSEP => '=',
OUT_FILENAME => 'ks',
OUT_SUFXSTOR => 'storable',
VAL_MIN      => 15,
VAL_MAX      => 3600,
};
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This does not work as intended:

print <<USAGE;

This program does this and that with the OUT_DIR. The filename is
OUT_FILENAME and the file suffix is OUT_SUFXSTOR.

Fields are separated with the OUT_FIELDSEP character. Enter a value
between VAL_MIN and VAL_MAX.

USAGE
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What I've resort to doing:

my $out_dir = OUT_DIR;
my $out_fs  = OUT_FIELDSEP;
my $out_fn  = OUT_FILENAME;
my $out_sx  = OUT_SUFXSTOR;
my $valmin  = VAL_MIN;
my $valmax  = VAL_MAX;

print <<USAGE;

This program does this and that with the $out_dir. The filename is
$out_fn and the file suffix is $out_sx.

Fields are separated with the $out_fs character. Enter a value
between $valmin and $valmax.

USAGE
[download]

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