[texhax] ifthen functionality for plain TeX

[Alexander Grahn]

Hi,

is there a way to get the functionalty of the LaTeX package `ifthen' in
TeX too? I am particularly interested in negating and combining boolean
expressions using \NOT, \AND, \OR.

It is surprising that TeX doesn't provide this functionality by itself,
as building complex conditional expressions is quite a common task and
even the most ancient and most primitive higher programming languages
provide the means for doing such things.

Regards,
Alexander