Of course one can make computation on those types, but it is so un-natural that it scares me :
* BigDecimal for currency, let me laugh * Date/timestamp without proper casting rules * Types towers with inheritance, generics, etc. Pfff... * Still no fine library to represent an address * Representing mutable ordered lists in SQL databases is still quite painful (possible, sure, but there's so boiler plate code to write)
So the data representation/manipulation problem, which goes with the data longevity you observe, that's something to learn about...
There's no reason to love current programming languages :-( (but I do love Python :-) 3 of course :-))
F#'s units are nice.
> Computing with dates in a sensible way
The new Java time API is pretty good. But honestly my favourite datetime API would have to be Postgres'.
> BigDecimal for currency, let me laugh
Out of curiosity, why?
For BigDecimal, my grief is that it makes code horrible (at least in my experience, I'm still locked in JDK 1.7).
BigDecimal has the problem I see with the rest of my griefs : it is possible to compute things correctly with code (obviously), but the way the code is written is ugly (and painful).
BigDecimal yearly_amount = new BigDecimal("1000.00");
BigDecimal daily_amount = yearly_amount.divide(new BigDecimal("12")); // Beware the rounding issue
Wouldn't it be nicer if : money<4> yearly_amount = 1000.00 EUR; // 4 decimals
money<2> daily_amount = yearly_amount / 12; // Beware the rounding issue !
Of course, this notation doesn't help much with rounding, but at least it makes the code easier to read. And trust me, using BigDecimal, doesn't prevent many people of making mistakes with rounding.If we all give up and just use mainstream languages, then the future will be filled with copies of mainstream languages.
Besides, data outlives code. By orders of magnitude. You seem to be in love with Haskell today, chances are you'll be using a different language in ten years but the data you'll be working with will probably have been around for much longer than that.
Don't fall in love with programming languages, it's a waste of emotional energy.