 : friday-of-month ( timestamp n -- new-timestamp ) 5 nth-day-this-month ;
 : saturday-of-month ( timestamp n -- new-timestamp ) 6 nth-day-this-month ;
 
+: last-sunday-of-month ( timestamp -- new-timestamp ) 0 last-day-this-month ;
+: last-monday-of-month ( timestamp -- new-timestamp ) 1 last-day-this-month ;
+: last-tuesday-of-month ( timestamp -- new-timestamp ) 2 last-day-this-month ;
+: last-wednesday-of-month ( timestamp -- new-timestamp ) 3 last-day-this-month ;
+: last-thursday-of-month ( timestamp -- new-timestamp ) 4 last-day-this-month ;
+: last-friday-of-month ( timestamp -- new-timestamp ) 5 last-day-this-month ;
+: last-saturday-of-month ( timestamp -- new-timestamp ) 6 last-day-this-month ;
+
 : beginning-of-week ( timestamp -- new-timestamp )
     midnight sunday ;
 

: milliseconds ( x -- duration ) 1000 / seconds ;
: microseconds ( x -- duration ) 1000000 / seconds ;
: nanoseconds ( x -- duration ) 1000000000 / seconds ;

GENERIC: leap-year? ( obj -- ? )


    dup timestamp [ month>> ] bi@ = [ 1 weeks time+ ] unless
    n 1 - [ weeks time+ ] unless-zero ;

: last-day-this-month ( timestamp day -- new-timestamp )
    [ 1 months time+ 1 ] dip nth-day-this-month 1 weeks time- ;

PRIVATE>

GENERIC: january ( obj -- timestamp )
GENERIC: february ( obj -- timestamp )
GENERIC: march ( obj -- timestamp )
GENERIC: april ( obj -- timestamp )
GENERIC: may ( obj -- timestamp )
GENERIC: june ( obj -- timestamp )
GENERIC: july ( obj -- timestamp )
GENERIC: august ( obj -- timestamp )
GENERIC: september ( obj -- timestamp )
GENERIC: october ( obj -- timestamp )
GENERIC: november ( obj -- timestamp )
GENERIC: december ( obj -- timestamp )

M: integer january 1 1 <date> ;
M: integer february 2 1 <date> ;
M: integer march 3 1 <date> ;
M: integer april 4 1 <date> ;
M: integer may 5 1 <date> ;
M: integer june 6 1 <date> ;
M: integer july 7 1 <date> ;
M: integer august 8 1 <date> ;
M: integer september 9 1 <date> ;
M: integer october 10 1 <date> ;
M: integer november 11 1 <date> ;
M: integer december 12 1 <date> ;

M: timestamp january clone 1 >>month ;
M: timestamp february clone 2 >>month ;
M: timestamp march clone 3 >>month ;
M: timestamp april clone 4 >>month ;
M: timestamp may clone 5 >>month ;
M: timestamp june clone 6 >>month ;
M: timestamp july clone 7 >>month ;
M: timestamp august clone 8 >>month ;
M: timestamp september clone 9 >>month ;
M: timestamp october clone 10 >>month ;
M: timestamp november clone 11 >>month ;
M: timestamp december clone 12 >>month ;

: sunday ( timestamp -- new-timestamp ) 0 day-this-week ;
: monday ( timestamp -- new-timestamp ) 1 day-this-week ;
