I've not used units much so I'm a bit confused as to how they work...

Why does time := 69sec compile but size := 69kB does not?

Looking in FAN_HOME/etc/sys/units.txt there's a lot of definitions - but how do you reference them?

Literals like 69sec map to a Duration type which is implicitly based on time. The unit database is accessed with sys::Unit class.

Our commercial software SkySpark has a scripting language called Axon which actually does allow units with any number literal (based on Fantom unit database). It definitely has its pros and cons.

You'll want to check out the docs for sys::Unit.

Short version: 69sec is a duration literal and is part of the language grammar ( http://fantom.org/doc/docLang/Literals.html#duration ). 69kB is nothing at all unless you use the sys::Unit classes and methods.

Here would be some sample code:

MB := Unit.fromStr("MB")

B := Unit.fromStr("byte")

MB.convertTo(3.15f, B)

Cool,

Thanks for the example. For some reason I was under the impression that all units in units.txt became Fantom literals - I think I confused it with Duration.

So to reiterate (for future ref):

• there are no unit literals, just the sys::Unit class.
• there are sys::Duration literals of ns, ms, sec, min, hr & day

Oh, and the sys::Unit.convertTo doc says:

m  := Unit.find("meter")
km := Unit.find("kilometer")

it should be:

m  := Unit.fromStr("meter")
km := Unit.fromStr("kilometer")

thanks, I fixed docs