RosettaCodeData/Task/Left-factorials/Factor/left-factorials.factor

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700 B
Factor

USING: formatting fry io kernel math math.factorials
math.functions math.parser math.ranges sequences ;
IN: rosetta-code.left-factorials
: left-factorial ( n -- m ) <iota> [ n! ] map-sum ;
: print-left-factorials ( seq quot -- )
'[
dup left-factorial @
[ number>string "!" prepend ] dip
"%6s %-6d\n" printf
] each nl ; inline
: digit-count ( n -- count ) log10 >integer 1 + ;
: part1 ( -- ) 11 <iota> [ ] print-left-factorials ;
: part2 ( -- ) 20 110 10 <range> [ ] print-left-factorials ;
: part3 ( -- )
"Number of digits for" print
1,000 10,000 1,000 <range>
[ digit-count ] print-left-factorials ;
: main ( -- ) part1 part2 part3 ;
MAIN: main