--- Day 4: Secure Container ---

Factor

273025 767253 [a,b]                                          ! input range
[ 1 digit-groups reverse ] [ [ <= ] monotonic? ] map-filter  ! get a sequence of sequences of monotonically increasing digits
[ 2 clump [ first2 = ] any? ] filter dup length .            ! part 1
[ [ = ] monotonic-split [ length 2 = ] any? ] count .        ! part2

Edit: I made a version that's 80 times faster (10 ms vs. 800 ms). Because I generate monotonically increasing numbers directly, rather than filtering them from the natural numbers.

: d ( m -- n n ) 9 [a,b] amb-lazy dup ;

[ 1 d d d d d d drop 6 narray ] bag-of                           ! generate all 6-digit monotonically increasing sequences
[ reverse [ 10^ * ] map-index sum ]                              ! constrain to
[ 273025 767253 between? ] map-filter                            ! input range
[ number>string ] map [ [ 2 clump [ first2 = ] any? ] count . ]  ! part 1
[ [ [ = ] monotonic-split [ length 2 = ] any? ] count . ] bi     ! part 2