Timesheets

Package: TIME_PACKAGE, with the hourly rate coming from UOM_PACKAGE. Both are registered by createEngine(); for a slimmer engine, register them explicitly (see choosing packages).

A timesheet is the same three sums every week. How long was each day, what do they come to, and what is that worth.

Adding the days up

A worked day is usually written the way a clock shows it, 8:15 for eight hours and a quarter. Add them together and you get the week.

8:15 + 7:45 // 960 minutes
8:15 + 7:45 + 8:30 // 1,470 minutes

The total comes back in minutes, which is the unit every duration in the engine is counted in, and in hours is how a timesheet usually wants to read it.

8:15 + 7:45 + 8:30 in hours // 24.50 hours

It is an ordinary duration once it is added up, so it goes on being one: more time can be added to it, and it can be priced.

8:15 + 7:45 + 30 minutes // 990 minutes
8:15 + 7:45 at £15/hour // £240.00

When a time is a time of day, not a length

8:15 on its own is quarter past eight this morning, and it still is. It only means eight and a quarter hours when it is added to another clock time, which is the only reading that sum can have. Add a duration to it instead and it stays a point in the day: 8:15 + 30 minutes is quarter to nine this morning, a date and a time, exactly as it was before any of this.

A time written with am or pm is a time of day and nothing else, so adding two of those is refused rather than answered: 9am + 5:30pm is not a length of anything. Write the day as 8:15 if it is a stretch of time, and as 9am if it is a point in the day.

- between two clock times is left alone for the same reason the engine leaves it alone elsewhere: 5pm - 7pm reads as a range and 5pm - 2pm as a subtraction, and guessing between them would be worse than not answering.

From clocking in to clocking out

If what you have is the two ends of the day rather than its length, to gives the stretch between them.

9:00 to 17:30 // 510 minutes
9am to 5:30pm // 510 minutes

A shift that runs past midnight is the stretch it actually is, not a negative number: the end is read as the next day.

9pm to 5am // 480 minutes

Clocking in and out with a minus sign

Subtracting one clock time from another is the same question to asks, written the way a payslip writes it, and the answer comes back on a clock rather than as a count of minutes: 1:00 is one hour, 7:05 is seven hours and five minutes.

9:30 - 8:30 // 1:00
18:00 - 12:55 // 5:05

A line reads left to right, so time added after the shift is added to the shift: a day of 9:00 to 17:30 with forty-five minutes of overtime is 9:15, and a bare 0:45 there is a length of time rather than a quarter to one.

17:30 - 9:00 + 0:45 // 9:15
18:00 - 12:55 + 1:00 + 0:30 // 6:35

A stretch of time measured this way stays one through the arithmetic that keeps it a stretch. Two of them add together, one scales by a number, and a column of them totals, so a week of shifts reads as a week rather than as a number of milliseconds.

9:30 - 8:30
12:00 - 11:00
18:00 - 12:55
total above // 7:05

Adding or taking away a length of time keeps it a stretch too: an hour’s shift and a half-hour’s overtime is an hour and a half, on the clock.

(9:30 - 8:30) + 30 minutes // 1:30
(9:30 - 8:30) - 15 minutes // 0:45

Ask for a unit and you are given that unit, because the line said which one it wanted:

(9:30 - 8:30) in minutes // 60 minutes

The boundary is a quantity of milliseconds somebody typed. 40ms is a number with a unit on it, the way 40 kg is, and a latency budget adds up as one:

40ms + 120ms + 30ms // 190.00 ms
2 minutes in ms // 120,000.00 ms

Both are milliseconds and the unit cannot tell them apart, so the engine remembers which of the two it measured. A stretch between two times shows as a clock; a figure you wrote down stays a figure. That holds when the two meet: a clock shows whole seconds, so (9:30 - 8:30) + 40ms stays in the milliseconds it was given rather than dropping them.

A time of day on its own is a moment, not an amount, so it cannot be multiplied, divided, negated, rounded or given a unit. Each of those is refused by name, and points at the ways a length of time is written:

1:30:00 * 3 // 16,200.00 s
1h30m * 3 // 270 minutes
1:30 * 3 // A date or time cannot be multiplied: it is a moment, not an amount. A length of time is written 1h30m, 90 minutes or 1:30:00.
1:30 hours // A date or time cannot take a unit, hours: it is a moment, not an amount. A length of time is written 1h30m, 90 minutes or 1:30:00.

What it pays

An hourly rate turns any of these into money. The duration does not have to be in hours: the rate carries its own unit, so minutes and spans work too.

40 hours at £15/hour // £600.00
9:00 to 17:30 at £15/hour // £127.50

per reads the same as the slash, and the rate can be written either way round for the currency you use.

9:00 to 17:30 at £15 per hour // £127.50