Check out my program

#include <stdio.h>
#include <unistd.h>
#define LEN 15
int print(i,j) {
for (; i < LEN; ++i)
printf(" ");
puts("a");
usleep(50000);
return 0;
}
int main(void)
{
int i, j;
for(;;) {
for (j = 0; j < LEN; print(i), ++j)
i = j;
for (j = 0; j < LEN; print(i), ++j)
i = LEN-1-j;
}
return 0;
}

Do you like it?

At first I tried to make it be the SICP snake, with the head going down, but it was too hard for me.

#!/usr/bin/perl
use strict; # PERL by Example (2015) p. 77
use warnings; # PERL by Example (2015) p. 85
our $cns = 32; # size of AI memory for central nervous system.
our $IQ = 0; # PERL by Example (2015) p. 689
our @aud = " "; # PERL by Example (2015) p. 17: auditory array
our $t = 0; # Lifetime experiential time "$t"
sub AudInput; # PERL by Example p. 351 Forward declaration
sub sensorium; # PERL by Example p. 351 Forward declaration
sub think; # PERL by Example p. 351 Forward declaration
sub VisRecog; # PERL by Example p. 351 Forward declaration
TabulaRasa: { # PERL by Example (2015), p. 204: Labels
my $trc = 0; # $trc variable is "tabula rasa counter".
print "Size of experiential memory is $cns \n"; # Increase as needed.
until ($trc == $cns) { # PERL by Example (2015), p. 193: "Loops".
$aud[$trc] = " "; # Fill CNS memory with blank spaces.
$trc++; # PERL by Example (2015) p. 21: autoincrement $trc.
} # End of loop filling auditory memory with blank engrams.
} # End of TabulaRasa "clean slate" sequence.
EnBoot: { # http://mind.sourceforge.net/enboot.html
$t = 0; # English Bootstrap sequence stretches over mental time "$t".
print "English bootstrap is loading into memory... \n";
$t = 0; $aud[$t] = "H"; # Indexing of array begins with zero.
$t = 1; $aud[$t] = "E"; # Single elements of array use $aud not @aud.
$t = 2; $aud[$t] = "L"; # PERL by Example (2015), p. 95: Elements
$t = 3; $aud[$t] = "L"; # AudMem() stores new words at higher $t values.
$t = 4; $aud[$t] = "O"; # Bootstrap "HELLO" is not permanently here.
$t = 5; # A blank gap is necessary between words.
$t = 6; # More bootstrap words will be needed.
}; # http://code.google.com/p/mindforth/wiki/EnBoot
while ($IQ < 8) { # PERL by Example (2015), p. 190
sensorium(); # PERL by Example p. 350: () empty parameter list
think(); # PERL by Example p. 350: () empty parameter list
} # End of main loop calling mind.pl Strong AI subroutines
sub sensorium() { # Start sensory input through sensory modalities.
print " Sensorium: Calling AudInput subroutine: \n";
AudInput(); # PERL by Example p. 350: () empty parameter list
# VisRecog(); -- non-existent subroutine is shown but commented out
} # End of sensorium subroutine in Perl artificial intelligence
sub AudInput() { # As if keyboard input were auditory hearing.
print " AudInput: Enter new IQ: ";
$IQ = <STDIN>; # PERL by Example (2015), p. 50
} # End of auditory input for human-computer interaction
sub think() { # Start showing output as if generated by thinking.
print "Think: My IQ is now $IQ";
} # http://ai.neocities.org/AiSteps.html