Onager (weapon) Onager (weapon) The onager (British /ˈɒnədʒə/, /ˈɒnəɡə/, U.S. /ˈɑnədʒər/) was an imperial-era Roman torsion powered siege engine; in other words, a small catapult. The onager was first mentioned in 353 AD by Ammianus Marcellinus, who described onagers as the same as a scorpion. According to two authors of the later Roman Empire who wrote on military affairs, the onager derived its name from the kicking action of the machine that threw stones into the air, as did the hooves of the wild ass, the onager, which was native to the eastern part of the empire. The onager consisted of a
Type system or an "effect system", which enables even more program specifications to be verified by a type checker. Beyond simple value-type pairs, a virtual "region" of code is associated with an "effect" component describing "what" is being done "with what", and enabling for example to "throw" an error report. Thus the symbolic system may be a "type and effect system", which endows it with more safety checking than type checking alone. Whether automated by the compiler or specified by a programmer, a type system makes program behavior illegal if outside the type-system rules. Advantages provided by programmer-specified type systems include: Advantages