Each time you call the anonymous sub constructor it creates a new closure already. What exactly do you mean by "adjust the type"? Something like this perhaps?

sub instantiator {
  my $state = shift;

  if( $state eq 'scalar' ) {
    return sub { ... something scalarly ... }
  } elsif( $state eq 'array' ) {
    return sub { ... an array of possibilities ... }
  } else { # hash
    return sub { ... make a complete hash of things ... }
  }
}
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Update: Aaah. You can overload &{}, so perhaps you could use that to do what you want (i.e. you return an object rather than a sub ref which has an overloaded &{} that examines whatever and then behaves differently).

package Foo;

use overload "&{}" => \&deref;

sub instatntiate {
  my $state = shift;

  # ...

  return bless { _original_code => sub { ... } }
}

sub deref {
  my $self = shift;
  ## examine $self and create $newsub using $self->{_original_code}
  $newsub->( @_ );
}

package main;

$f = Foo::instantiate( ... );

$f->( $a, $b, $c );
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