USING: formatting io kernel math math.parser sequences
splitting.monotonic ;
IN: rosetta-code.range-extraction

: make-range ( seq -- str )
    [ first ] [ last ] bi "%d-%d" sprintf ;

: make-atomic ( seq -- str ) [ number>string ] map "," join ;

: extract-range ( seq -- str )
    [ - -1 = ] monotonic-split
    [ dup length 2 > [ make-range ] [ make-atomic ] if ] map
    "," join ;

{
    0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22
    23 24 25 27 28 29 30 31 32 33 35 36 37 38 39
} extract-range print