I wanted to make something distinctly perl, and despite its many powers, perl is best known for its unmatched text manipulation capabilities. Therefore, I endevored to write a binary clock program based upon string matching. It operates as a finite state machine, where the current state is the binary string representing each digit. No arithmatic takes place.

I was able to construct the core of the clock in one horrendously (beautiful?) long line of code,with a couple of extra lines for initilization and printing.

The current time can be set using command line aurguments like:

perl 438277.pl 0000 0011 0001 0111

The example above sets the current time to 3:17. The clock defaults to 1:00 if no command line aurguments are provided. 

use warnings;use strict;
(@ARGV eq 4)?(($",$~,$:,$.) = @ARGV,$^=$_='0000'):
($"=$_=$^=$.=$:='0000',$~='0001');{$|=1;select $,,$,,$,,1;
((s:0000:0001:)?():((s:0001:0010:)?():((s:0010:0011:)?():((s:0011:0100
+:)?():((s:0100:0101:)?():((s:0101:0110:)?():((s:0110:0111:)?():((s:01
+11:1000:)?():((s:1000:1001:))))))))))?():((s:1001:0000:)?((($^=~s:000
+0:0001:)?():(($^=~s:0001:0010:)?():(($^=~s:0010:0011:)?():(($^=~s:001
+1:0100:)?():(($^=~s:0100:0101:))))))?():(($^=~s:0101:0000:)?((($.=~s:
+0000:0001:)?():(($.=~s:0001:0010:)?():(($.=~s:0010:0011:)?():(($.=~s:
+0011:0100:)?():(($.=~s:0100:0101:)?():(($.=~s:0101:0110:)?():(($.=~s:
+0110:0111:)?():(($.=~s:0111:1000:)?():(($.=~s:1000:1001:))))))))))?()
+:(($.=~s:1001:0000:)?((($:=~s:0000:0001:)?():(($:=~s:0001:0010:)?():(
+($:=~s:0010:0011:)?():(($:=~s:0011:0100:)?():(($:=~s:0100:0101:))))))
+?():(($:=~s:0101:0000:)?((($~=~s:0000:0001:)?():(($~=~s:0001:0010:)?(
+):(($~=~s:0010:0011:)?(($"=='0001')?($~=$",$"='0000'):()):(($~=~s:001
+1:0100:)?():(($~=~s:0100:0101:)?():(($~=~s:0101:0110:)?():(($~=~s:011
+0:0111:)?():(($~=~s:0111:1000:)?():(($~=~s:1000:1001:))))))))))?():((
+$~=~s:1001:0000:)?(($"=~s:0000:0001:)?():($"=~s:0001:0000:)):())):())
+):())):())):()),
(print "\r",$",' ',$~,':',$:,' ',$.,':',$^,' ',$_)&&redo}

[download]
If you really want time to fly, change the '1' in the 'select $,,$,,$,,1;' statement to '0'.

UPDATE: Something went wrong when I posted the code the first time. I have replaced it with code that should work as advertized.

In reply to Binary Clock Implemented Through String Matching by ktross

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