构建规范语言表示的一般复杂性是什么？

It is often handy to have a canonical representation of a language (in my case they are usually domain specific languages); however, I believe there are strict limits on the expressiveness of the languages involved that determine whether a canonical form can be determined and/or created for an arbitrary program in that language. Unfortunately, I've been unable to find the references that I (vaguely) recall reading about this in.It is often handy to have a canonical represent