/Prog/ramming Language

Hi /prog/, I was wondering what's the closest programming language that can do:


type percentage int x where x >= 0 and x <= 100
percentage discount = 25
# the above will not compile if e.g, discount = 9001
print discount

You get the idea, I found types lacking in conventional programming languages.

>>4
Yes, but it could be used for much more than subranges, e.g,

type smart_student student s where s.grade > 90
This is pretty DRY, obvious, straightforward, avoids bugs, all which leads to better spec-to-code process in our industry. Why isn't this kind of typing be more adopted? Enlighten me, /prog/