Conversions

Unit conversions

The conversion operator -> attempts to convert the physical quantity on its left hand side to the unit of the expression on its right hand side. This means that you can write an arbitrary expression on the right hand side — but only the unit part will be extracted. For example:

# simple unit conversion:
> 120 km/h -> mph

  = 74.5645 mi/h

# expression on the right hand side:
> 120 m^3 -> km * m^2

  = 0.12 m²·km

# convert x1 to the same unit as x2:
> let x1 = 50 km / h
> let x2 = 3 m/s -> x1

  x2 = 10.8 km/h

Quote

"The metric system is the tool of the devil! My car gets 40 rods to the hogshead and that's the way I likes it." — Grandpa Simpson, A Star Is Burns (S06E18)

Example

To convert the mileage of Grandpa's car to miles per gallon, you can write:

>>> 40 rods / hogshead -> mpg

    = 0.00198413 mi/gal    [Length⁻²]

And for supporters of Marge's side could use something like:

100 km / (40 rods / hogshead) -> l

    = 118548 l    [Volume]

Conversion functions

The conversion operator -> (or to) can not just be used for unit conversions, but also for other types of conversions. The way this is set up in Numbat is that you can call x -> f for any function f that takes a single argument of the same type as x.

The following functions are available for this purpose:

# Convert a date and time to a Unix timestamp
now() -> unixtime

# Convert a date and time to a different timezone
now() -> tz("Asia/Kathmandu")

# Convert a duration to years, months, days, hours, minutes, seconds
10 million seconds -> human

# Convert an angle to degrees, minutes, seconds (48° 46′ 32″)
48.7756° -> DMS

# Convert an angle to degrees, decimal minutes (48° 46.536′)
48.7756° -> DM

# Convert a number to its binary representation
42 -> bin

# Convert a number to its octal representation
42 -> oct

# Convert a number to its hexadecimal representation
2^31-1 -> hex

# Convert a code point number to a character
0x2764 -> chr

# Convert a character to a code point number
"❤" -> ord

# Convert a string to upper/lower case
"numbat is awesome" -> uppercase
"vier bis elf weiße Querbänder" -> lowercase

Note that the tz(…) call above returns a function, i.e. the right hand side of the conversion operator is still a function.