ref: f666a9b2a62c4f8588c6add2bcc2071f95ef357c
dir: /test/trait.myr/
use std trait frobable @a = frob : (val : @a -> @a) ;; impl frobable int = frob = {val -> val * 2 } ;; generic foo = {x : @a::frobable -> frob(x) } const main = { std.exit(foo(12)) }