/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.

>>2
Ada seems interesting; any easy way to get Ada compiler working on osx?