A LAMBDA Exercise

Patrick2788 

I was undecided whether to delicately unwrap the calendar format into meaningful arrays or to simply hit it with a blunt instrument, COUNTIFS in the present case.  I came to the conclusion that the latter was sufficient, provided I was allowed to mark the holiday as a named range.

Worksheet formula
= rate * MAP(staff, Hoursλ);

Hoursλ = LAMBDA(s,
    8 * SUM(COUNTIFS(holiday, s), dayRate * BYCOL(july, LAMBDA(day, COUNTIFS(day, s))))
);

dayRate = {1.5, 1, 1, 1, 1, 1, 1.5};

One thing that I would observe about Patrick's original solution, is that 'hours()' is a Lambda function and therefore will accept parameters directly from the helper functions without the use of an additional Lambda to pass parameters.  I only realised that once I had reduced my own formula by naming its Lambda function to be "Hoursλ".