#

# a perl koan designed for a true perl monk
use warnings;
use strict;
my $this; # do I need this and that?
my $that; # tell me oh perl monks!

# a structured way of thinking, 
# the params is a way to pass the parameters
# and the thought is what to do with them
sub koan
{
    my $params = shift; # the code ref is a parameter 
                        # that defines the parameters

    my $thought = shift; # the code ref that 
                         # defines the work
    return sub {
    &$params(@_);  # Get the parameters, 
                       # from @_ and make them 
                       # available in thought

    &$thought; # Do the work using these parameters
    }
};

# create a closure to think about the thought
sub zen
{
    my $thought = shift;
    my @params  = @_;
    return sub {
    
    &$thought(@params); # call with the saved params

    };
};

sub integer_parm # called to get a simple integer
{
    my $val= shift;         # the value passes
    my $type = ref $val;    # get the type of param
    return $val if(!$type); # return simple values
    if ($type eq "CODE")
    {
     $val = &$val; # eval the parameter
    }
    else
    {
    die "no refs in this"; # dont allow pointers
    }
    die unless $val =~ /^\d+$/; 
    # the value of the param must be an integer
    return $val;
}

###############################################
# different thoughts to meditate on

# types of thoughts
my $binary_thought = sub {
    $this = shift; # now I want to have 
                   # this available in koan 
                   # and to the thought,

    $that = shift; # but not to be overwritten 
                   # if called recursivly

    $this=integer_parm($this);
    $that=integer_parm($that);
};

my $add_func   = sub { $this + $that; };
my $minus_func = sub { $this - $that; };

# different thoughts
my $add_koan = koan($binary_thought,$add_func);
my $minus_koan = koan($binary_thought,$minus_func);

## SOME EXAMPLES 
print &$add_koan(1,1); # direct thought

my $thought = zen($add_koan,1,2); # indirect thought
print &$thought . "\n";
print &$add_koan(1,$thought) . "\n"; # tree of thoughts

#mdupont
#
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