#!/usr/bin/perl
use strict;
use warnings;

my $name;
my $upto;
my @response = ("That's interesting.","Eh, boring...","Ugh.","Cool!  Keep up the good work!");

sub april {
print "Hi, my name is April!  What's yours? ";
chomp($name = <STDIN>);
print "Hi ", $name, ", nice to meet you!  What are you up to? ";
for (;;) {
chomp($upto = <STDIN>);
$upto eq "nothing" and last;
print $response[rand @response], "\n";
print "Anything else? ";
}
print "Goodbye, $name!\n";
}

april();

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;

my @response = (
    "That's interesting.",
    "Eh, boring...",
    "Ugh.",
    "Cool!  Keep up the good work!"
);

chat('April', @response);

sub chat {
    my ($my_name, @responses) = @_;
    print "Hi, my name is $my_name!  What's yours? ";
    chomp(my $name = <STDIN>);
    print "Hi $name, nice to meet you!  What are you up to? ";
    my $response = '';
    until ($response eq 'nothing') {
        chomp($response = <STDIN>);
        print $responses[rand @responses], "\n";
        print "Anything else? ";
    }
    print "Goodbye, $name!\n";
}

##</code><code>##

    (define (new-if predicate then-clause else-clause)
      (cond (predicate then-clause)
            (else else-clause)))

    (define (sqrt x)
      (define (sqrt-iter guess x)
        (new-if (good-enough? guess x)
          guess
          (sqrt-iter (improve guess x) x)))
      (define (improve guess x)
        (average guess (/ x guess)))
      (define (average x y)
        (/ (+ x y) 2))
      (define (good-enough? guess x)
        (< (abs (- (square guess) x)) 0.001))
      (sqrt-iter 1.0 x))