USING: accessors grouping io kernel math regexp sequences
splitting strings unicode ;

: numeric ( str -- new-str )
    R/ [1-9][0-9]*/ first-match >string ;

: commas ( numeric-str period separator -- str )
    [ reverse ] [ group ] [ reverse join reverse ] tri* ;

: (commatize) ( text from period separator -- str )
    [ cut dup numeric dup ] 2dip commas replace append ;

: commatize* ( text from period separator -- str )
    reach [ digit? ] any? [ (commatize) ] [ 3drop ] if ;

: commatize ( text -- str ) 0 3 "," commatize* ;

"pi=3.14159265358979323846264338327950288419716939937510582097494459231"
5 5 " " commatize* print

"The author has two Z$100000000000000 Zimbabwe notes (100 trillion)."
0 3 "." commatize* print

{
    "\"-in Aus$+1411.8millions\""
    "===US$0017440 millions=== (in 2000 dollars)"
    "123.e8000 is pretty big."
    "The land area of the earth is 57268900(29% of the surface) square miles."
    "Ain't no numbers in this here words, nohow, no way, Jose."
    "James was never known as 0000000007"
    "Arthur Eddington wrote: I believe there are 15747724136275002577605653961181555468044717914527116709366231425076185631031296 protons in the universe."
    "   $-140000±100 millions."
    "6/9/1946 was a good year for some."
} [ commatize print ] each