Doing it with substitutions

sub bowlscore 
 {
   my $t;
   $_=join(',',@_);
   while(s/X,X,X/30,X,X/){}
   s!X,X,(\d)!20+$1.",X,$1"!eg;
   s!X,(\d),(\d)!10+$1+$2.",$1,$2"!eg;
   s!X,\d,/!20,1,/!g;
   s!\d,/,(\d)(\b)!10+$1.",$1$2"!eg;
   s!\d,/(?=,\d\d)!20!g;
   s!(\d\d)(,\d){1,2}$!$1!;
   map($t+=$_,split(/,/));
   $t;
 }
[download]

223 chars not counting the unnecessary whitespace for the body of the function. It's not the lowest bytecount here, but at least it's lower than my bowling highscore.

Update: This fixes a bug pointed out by dragonchild

sub bowlscore 
 {
   my $t;
   $_=join(',',@_);
   while(s/X,X,X/30,X,X/){}
   s!X,X,(\d)!20+$1.",X,$1"!eg;
   s!X,(\d),(\d)!10+$1+$2.",$1,$2"!eg;
   s!X,\d,/!20,0,/!g;
   s!/,X!20!;
   s!\d,/,(\d)(\b)!10+$1.",$1$2"!eg;
   s!\d,/(?=,\d\d)!20!g;
   s!(\d\d)(,\d){1,2}$!$1!;
   map($t+=$_,split(/,/));
   $t;
 }
[download]

10 chars added.

And another correction:
s!\d,/,(\d)(\b)!10+$1.",$1$2"!eg;
should be
while(s!\d,/,(\d)(\b)!10+$1.",$1$2"!eg){}
for multiple spare frames in a row to work.

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.