DB<22> p $_ = join "," , A..E
A,B,C,D,E
  DB<23> p m/(,.*,)/  # longest possibility from first comma to last comma
,B,C,D,
  DB<24> p m/(,.*?,)/ # shortest possibility from first comma to next comma
,B,
  DB<25> p m/(,.*$)/  # longest possibility from first comma to end of line
,B,C,D,E
  DB<26> p m/(,.*?$)/ # shortest possibility from first comma to end of line
,B,C,D,E
  DB<27> 

##</code><code>##

  DB<27> p m/(,[^,]*)$/ # comma followed by non-commas till EOL
,E

##</code><code>##

  DB<32> ; m/(,[^,]*) (?{say $1}) $/x #show all intermediate attempts to match $1 until it doesn't fail
,B
,
,C
,
,D
,
,E
  DB<33> 

##</code><code>##

  DB<34> ; m/(,[^,]*?) (?{say $1}) $/x #show all intermediate attempts to match $1
,
,B
,
,C
,
,D
,
,E

  DB<35>