Last Friday of each month: Difference between revisions

=={{header|zkl}}==

Gregorian calendar

<lang zkl>var [const] D=Time.Date;

fcn lastFridays(y){[1..12].pump(Console.println,

'wrap(m){ds:=D.daysInMonth(y,m);

[ds..1,-1].pump(Void,fcn(y,m,d){

D.weekDay(y,m,d) :

if (_==5)return(Void.Stop,"%d-%02d-%02d".fmt(y,m,d))

}.fp(y,m))

})

}

lastFridays(2012)</lang>

For each month in year y, count back from the last day in the month until a Friday is found and print that date. A pump is a loop over a sequence and Void.Stop stops the pump with a value. The first parameter to a pump is the sink. All the imperative loop constructs are available but I didn't feel like using them. A wrap is a function closure over unknown values in the function, necessary because functions are not lexically scoped.

{{out}}

<pre>

2012-01-27

2012-02-24

2012-03-30

2012-04-27

2012-05-25

2012-06-29

2012-07-27

2012-08-31

2012-09-28

2012-10-26

2012-11-30

2012-12-28

</pre>